Guidance for Industry

Nonsterile Semisolid Dosage Forms

Scale-Up and Postapproval Changes: 

Chemistry, Manufacturing, and Controls;

In Vitro Release Testing and In Vivo

Bioequivalence Documentation

U.S. Department of Health and Human Services

Food and Drug Administration

Center for Drug Evaluation and Research (CDER)

May 1997

SUPAC-SS

CMC 7
Guidance for Industry

Nonsterile Semisolid Dosage Forms

Scale-Up and Postapproval Changes: 

Chemistry, Manufacturing, and Controls;

In Vitro Release Testing and In Vivo

Bioequivalence Documentation

Additional copies are available from:

Office of Training and Communications 

Division of Communications Management

The Drug Information Branch, HFD-210

5600 Fishers Lane

Rockville, MD 20857

(Tel) 301-827-4573

(Internet) http://www.fda.gov/cder/guidance.htm

U.S. Department of Health and Human Services

Food and Drug Administration

Center for Drug Evaluation and Research (CDER)

May 1997

SUPAC-SS

CMC 7

Table of Contents
I. INTRODUCTION .................................................... 1

II. GENERAL BACKGROUND ........................................... 2

A. Critical Manufacturing Parameters ................................ 2

B. General Stability Considerations ................................... 3

C. The Role of In Vitro Release Testing ................................ 3

III. COMPONENTS AND COMPOSITION .................................. 4

A. Level 1 Change ................................................. 5

B. Level 2 Change ................................................. 6

C. Level 3 Change ................................................. 7

D. Preservative ................................................... 8

IV. MANUFACTURING ................................................. 10

A. Equipment ................................................... 10

B. Process ...................................................... 12

V. BATCH SIZE (SCALE-UP/SCALE-DOWN) ............................. 14

A. Level 1 Change ................................................ 14

B. Level 2 Change ................................................ 15

C. Level 3 Change ................................................ 16

VI. MANUFACTURING SITE ........................................... 16

A. Level 1 Change ................................................ 17

B. Level 2 Change ................................................ 17

C. Level 3 Change ................................................ 18

VII. IN VITRO RELEASE TEST ........................................... 19

VIII. IN VIVO BIOEQUIVALENCE STUDIES ................................ 25

GLOSSARY OF TERMS ................................................... 26
This guidance has been prepared by the Scale-Up and Post Approval Change Semisolids (SUPAC-SS) 1

Working Group operating under the direction of the Chemistry Manufacturing Controls Coordinating Committee (CMC

CC) and the Biopharmaceutics Coordinating Committee (BCC) in the Center for Drug Evaluation and Research

(CDER) at the Food and Drug Administration. This guidance document represents the Agency’s current thinking on

semisolid dosage forms scale-up and postapproval changes. It does not create or confer any rights for or on any person

and does not operate to bind FDA or the public. An alternative approach may be used if such approach satisfies the

requirement of the applicable statute, regulations, or both.

GUIDANCE FOR INDUSTRY1

Nonsterile Semisolid Dosage Forms

Scale-Up and Postapproval Changes:

Chemistry, Manufacturing, and Controls;

In Vitro Release Testing and

In Vivo Bioequivalence Documentation

SUPAC-SS

I. INTRODUCTION

This guidance provides recommendations to pharmaceutical sponsors of new drug applications

(NDAs), abbreviated new drug applications (ANDAs), and abbreviated antibiotic drug

applications (AADAs) who intend to change (1) the components or composition, (2) the

manufacturing (process and equipment), (3) the scale-up/scale-down of manufacture, and/or (4)

the site of manufacture of a semisolid formulation during the postapproval period. This guidance

addresses nonsterile semisolid preparations (e.g., creams, gels, lotions, and ointments) intended

for topical routes of administration. The guidance defines (1) the levels of change; (2)

recommended chemistry, manufacturing, and controls (CMC) tests to support each level of

change; (3) recommended in vitro release tests and/or in vivo bioequivalence tests to support each

level of change; and (4) documentation to support the change.

 The guidance specifies the application information that should be provided to the Center for Drug

Evaluation and Research (CDER) to ensure continuing product quality and performance

chacteristics of the semisolid topical formulation for specified changes. The guidance does not

comment on or otherwise affect compliance/inspection documentation defined by the Office of

Compliance in CDER or the Office of Regulatory Affairs at FDA. 

The guidance provides recommendations on application documentation for the following multiple
2

changes, provided appropriate test and filing documents are submitted (1) multiple level 1 changes

with level 1 test and filing documentation; (2) multiple level 1 changes; one level 2 change with

level 2 test and filing documentation; (3) multiple level 2 changes with level 2 test documentation

and a prior approval supplement (PAS) and (4) level 3 manufacturing site change and any other

level 1 change with level 3 manufacturing site change test and filing documentation. The

documentation to support the changes varies depending on the type and the complexity of the

semisolid dosage form. For those changes filed in a Changes Being Effected (CBE) Supplement

(21 CFR 314.70(c)), the FDA may review the supplemental information and decide that the

changes are not approvable. Sponsors should contact the appropriate CDER review division and

staff for information about tests and application documentation for changes not addressed in this

guidance, or for successive level 2 or 3 changes submitted over a short period.

The regulations provide that applicants may make changes to an approved application in

accordance with a guidance, notice, or regulation published in the Federal Register that provides

for a less burdensome notification of the change (e.g., by notification at the time a supplement is

submitted or in the next annual report) (21 CFR 314.70(a)). This guidance permits less

burdensome notice of certain postapproval changes within the meaning of

§ 314.70(a).

II. GENERAL BACKGROUND

In general, semisolid dosage forms are complex formulations having complex structural elements. 

Often they are composed of two phases (oil and water), one of which is a continuous (external)

phase, and the other of which is a dispersed (internal) phase. The active ingredient is often

dissolved in one phase, although occasionally the drug is not fully soluble in the system and is

dispersed in one or both phases, thus creating a three-phase system. The physical properties of

the dosage form depend upon various factors, including the size of the dispersed particles, the

interfacial tension between the phases, the partition coefficient of the active ingredient between

the phases, and the product rheology. These factors combine to determine the release

characteristics of the drug, as well as other characteristics, such as viscosity.

A. Critical Manufacturing Parameters

For a true solution, the order in which solutes are added to the solvent is usually

unimportant. The same cannot be said for dispersed formulations, however, because

dispersed matter can distribute differently depending on to which phase a particulate

substance is added. In a typical manufacturing process, the critical points are generally the

initial separation of a one-phase system into two phases and the point at which the active

ingredient is added. Because the solubility of each added ingredient is important for

determining whether a mixture is visually a single homogeneous phase, such data, possibly

supported by optical microscopy, should usually be available for review. This 
3

is particularly important for solutes added to the formulation at a concentration near or

exceeding that of their solubility at any temperature to which the product may be exposed.

Variations in the manufacturing procedure that occur after either of these events are likely

to be critical to the characteristics of the finished product. This is especially true of any

process intended to increase the degree of dispersion through reducing droplet or particle

size (e.g., homogenization). Aging of the finished bulk formulation prior to packaging is

critical and should be specifically addressed in process validation studies.

B. General Stability Considerations

The effect that SUPAC changes may have on the stability of the drug product should be

evaluated. For general guidance on conducting stability studies, see the FDA Guideline

for Submitting Documentation for the Stability of Human Drugs and Biologics. For

SUPAC submissions, the following points should also be considered:

1. In most cases, except those involving scale-up, stability data from pilot

scale batches will be acceptable to support the proposed change.

2. Where stability data show a trend towards potency loss or degradant

increase under accelerated conditions, it is recommended that historical accelerated

stability data from a representative prechange batch be submitted for comparison. 

It is also recommended that under these circumstances, all available long-term data

on test batches from ongoing studies be provided in the supplement. Submission

of historical accelerated and available long-term data would facilitate review and

approval of the supplement.

3. A commitment should be included to conduct long-term stability studies

through the expiration dating period, according to the approved protocol, on either

the first or first three (see section III-VI for details) production batches, and to

report the results in subsequent annual reports.

C. The Role of In Vitro Release Testing

The key parameter for any drug product is its efficacy as demonstrated in controlled

clinical trials. The time and expense associated with such trials make them unsuitable as

routine quality control methods. Therefore, in vitro surrogate tests are often used to

assure that product quality and performance are maintained over time and in the presence

of change. A variety of physical and chemical tests commonly performed on semisolid

products and their components (e.g., solubility, particle size and crystalline form of the

active component, viscosity, and homogeneity of the product) have historically provided

reasonable evidence of consistent performance. More recently, in vitro release testing has

shown promise as a means to comprehensively assure consistent delivery of the active
 FDA, CDER, Inactive Ingredient Guide, 1996, Division of Drug Information Resources. 2

4

component(s) from semisolid products. 

An in vitro release rate can reflect the combined effect of several physical and chemical

parameters, including solubility and particle size of the active ingredient and rheological

properties of the dosage form. In most cases, in vitro release rate is a useful test to assess

product sameness between prechange and postchange products. However, there may be

instances where it is not suitable for this purpose. In such cases, other physical and

chemical tests to be used as measures of sameness should be proposed and discussed with

the Agency. With any test, the metrics and statistical approaches to documentation of

“sameness” in quality attributes should be considered. 

The evidence available at this time for the in vitro-in vivo correlation of release tests for

semisolid dosage forms is not as convincing as that for in vitro dissolution as a surrogate

for in vivo bioavailability of solid oral dosage forms. Therefore, the Center’s current

position concerning in vitro release testing is as follows:

1. In vitro release testing is a useful test to assess product “sameness” under

certain scale-up and postapproval changes for semisolid products.

2. The development and validation of an in vitro release test are not required

for approval of an NDA, ANDA or AADA nor is the in vitro release test required

as a routine batch-to-batch quality control test.

3. In vitro release testing, alone, is not a surrogate test for in vivo

bioavailability or bioequivalence.

4. The in vitro release rate should not be used for comparing different

formulations across manufacturers.

III. COMPONENTS AND COMPOSITION

This section of the guidance focuses on changes in excipients in the drug product. Qualitative

changes in excipients should include only those excipients which are present in approved drug

products for the specific route of administration. Quantitative changes in excipients should not

exceed the amount previously approved in products with the same specific route of

administration. The chronology of changes in components and composition should be provided. 2

Changes in components or composition that have the effect of adding a new excipient or deleting

an existing excipient are defined as level 3 changes (see section III.C below), except as described

below. These changes generally result in the need to change the labeling.
5

Compositional changes in preservatives are considered separately and are not included as part of

the total additive effect under sections III.A, B and C.

A. Level 1 Change

1. Definition of Level

Level 1 changes are those that are unlikely to have any detectable impact on

formulation quality and performance.

Examples:

! Deletion or partial deletion of an ingredient intended to affect the color,

fragrance, or flavor of the drug product.

! Any change in an excipient up to 5% of approved amount of that excipient. 

The total additive effect of all excipient changes should not be more than

5%. Changes in the composition should be based on the approved target

composition and not on previous level 1 changes in the composition. A

change in diluent (q.s. excipient) due to component and composition

changes in excipient may be made and is excluded from the 5% change

limit.

! Change in a supplier of a structure forming excipient that is primarily a

single chemical entity (purity$95%) or change in a supplier or technical

grade of any other excipient. 

2. Test Documentation

a. Chemistry Documentation

Application/compendial product release requirements and stability testing.

Stability testing: First production batch on long-term stability reported in

annual report.

b. In Vitro Release Documentation

None.

c. In Vivo Bioequivalence Documentation

None.
6

3. Filing Documentation

Annual report (all information including long-term stability data).

B. Level 2 Change

1. Definition of Level

Level 2 changes are those that could have a significant impact on formulation

quality and performance. 

Examples:

! Changes of >5% and #10% of approved amount of an individual excipient. 

The total additive effect of all excipient changes should not be more than

10%. Changes in the composition should be based on the approved target

composition and not on previous level 1 or level 2 changes in the

composition. Changes in diluent (q.s. excipient) due to component and

composition changes in excipients are acceptable and are excluded from the

10% change limit.

! Change in supplier of a structure forming excipient not covered under level

1.

! Change in the technical grade of structure forming excipient.

! Change in particle size distribution of the drug substance, if the drug is in

suspension.

2. Test Documentation

a. Chemistry Documentation

Application/compendial product release requirements and executed batch

records.

Stability testing: One batch with three months accelerated stability data

reported in changes being effected supplement and long-term stability data

of first production batch reported in annual report.

b. In Vitro Release Documentation

The in vitro release rate of a lot of the new/modified formulation should be
7

compared with that of a recent lot of comparable age of the pre-change

formulation of the product. The median in vitro release rates (as estimated

by the estimated slope from each cell, see section VII) of the two

formulations should be demonstrated to be within acceptable limits using

the testing procedure described in section VII (IN VITRO RELEASE

TEST) below.

c. In Vivo Bioequivalence Documentation

None.

3. Filing Documentation

Changes being effected supplement (all information including accelerated stability

data); annual report (long-term stability data).

C. Level 3 Change

1. Definition of Level

Level 3 changes are those that are likely to have a significant impact on

formulation quality and performance.

Examples:

! Any qualitative and quantitative changes in an excipient beyond the ranges

noted in level 2 change.

! Change in crystalline form of the drug substance, if the drug is in

suspension.

2. Test Documentation

a. Chemistry Documentation

Application/compendial product release requirements and executed batch

records.Significant body of information available: One batch with three

months accelerated stability data reported in prior approval supplement and

long-term stability data of first three production batches reported in annual

report.
8

Significant body of information not available: Three batches with three

months accelerated stability data reported in prior approval supplement and

long-term stability data of first three production batches reported in annual

report. 

b. In Vitro Release Documentation

The in vitro release rate of the new/modified formulation should be

established as a point of reference. Under this level 3 change, in vitro

release documentation is not required, but sponsors are encouraged to

develop this information for use in subsequent changes under this guidance.

c. In Vivo Bioequivalence Documentation

Full bioequivalence study on the highest strength, with in vitro

release/other approach on the lower strength(s).

3. Filing Documentation

Prior approval supplement (all information including accelerated stability data);

annual report (long-term stability data).

D. Preservative

For semisolid products, any change in the preservative may affect the quality of the

product. If any quantitative or qualitative changes are made in the formulation, additional

testing should be performed. No in vitro release documentation or in vivo bioequivalence

documentation is needed for preservative changes.

1. Level 1 Change

a. Definition of Level

Quantitatively 10% or less change in the approved amount of preservative.

b. Test Documentation

! Application/compendial product release requirements.

! Preservative Effectiveness Test carried out at lowest specified

preservative level.

c. Filing Documentation
9

Annual report

2. Level 2 Change

a. Definition of Level

Quantitatively greater than 10% and up to 20% change in the approved

amount of preservative.

b. Test Documentation

! Application/compendial product release requirements.

! Preservative Effectiveness Test at lowest specified preservative

level.

c. Filing Documentation

Changes being effected supplement.

3. Level 3 change

a. Definition of Level

Quantitatively greater than 20% change in the approved amount of

preservative (including deletion) or use of a different preservative.

b. Test Documentation

! Application/compendial product release requirements.

! Preservative Effectiveness Test at lowest specified preservative

level.

! Analytical method for identification and assay for new preservative.

! Validation studies to show that the new preservative does not

interfere with application/compendial test.

! Executed batch records.

! Stability testing: One batch with three months accelerated stability

data reported in prior approval supplement and long-term stability
10

data of first production batch reported in annual report. 

c. Filing Documentation

Prior approval supplement (all information including accelerated stability

data); annual report (long-term stability data).

IV. MANUFACTURING

Manufacturing changes may affect both equipment used in the manufacturing process and the

process itself.

A. Equipment

1. Level 1 Change

a. Definition of Level

Change from nonautomated or nonmechanical equipment to automated or

mechanical equipment to transfer ingredients. Change to alternative

equipment of the same design and operating principles.

b. Test Documentation

i. Chemistry Documentation

Application/compendial product release requirements. Notification

of change and submission of updated executed batch records.

Stability testing: First production batch on long-term stability

reported in annual report.

ii. In Vitro Release Documentation

None.

iii. In Vivo Bioequivalence Documentation

None.

c. Filing Documentation
11

Annual report (all information including long-term stability data).

2. Level 2 Change

a. Definition of Level

Change in equipment to a different design or different operating principles. 

Change in type of mixing equipment, such as high shear to low shear and

vice versa.

b. Test Documentation

i. Chemistry Documentation

Application/compendial product release requirements. Notification

of change and submission of updated executed batch records.

Significant body of information available: One batch with three

months accelerated stability data reported in changes being effected

supplement and long-term stability data of first production batch

reported in annual report.

Significant body of information not available: Three batches with

three months accelerated stability data reported in changes being

effected supplement and long-term stability data of first three

production batches reported in annual report. 

ii. In Vitro Release Documentation

The in vitro release rate of a lot of the dosage form prepared in new

equipment should be compared with the release rate of a recent lot

of comparable age of the product prepared using original

equipment. The median in vitro release rates (as estimated by the

estimated slope from each cell, see section VII) of the two

formulations should be demonstrated to be within acceptable limits,

using the testing procedure described in section VII (IN VITRO

RELEASE TEST) below.

iii. In Vivo Bioequivalence Documentation

None.

c. Filing Documentation
12

Changes being effected supplement (all information including accelerated

stability data); annual report (long-term stability data).

3. Level 3 Change

No level 3 changes are anticipated in this category.

B. Process

1. Level 1 Change

a. Definition of Level

Process changes, including changes such as rate of mixing, mixing times,

operating speeds, and holding times within approved application ranges. 

Also, order of addition of components (excluding actives) to either oil or

water phase.

b. Test Documentation

i. Chemistry Documentation

None beyond application/compendial product release requirements.

ii. In Vitro Release Documentation

None.

iii. In Vivo Bioequivalence Documentation

None.

c. Filing Documentation

Annual report.

2. Level 2 Change

a. Definition of Level

Process changes, including changes such as rate of mixing, mixing times,

rate of cooling, operating speeds, and holding times outside approved

application ranges for all dosage forms. Also, any changes in the process
13

of combining the phases.

b. Test Documentation

i. Chemistry Documentation

Application/compendial product release requirements. Notification

of change and submission of updated executed batch records.

Significant body of information available: One batch with three

months accelerated stability data reported in changes being effected

supplement and long-term stability data of first production batch

reported in annual report.

Significant body of information not available: Three batches with

three months accelerated stability data reported in changes being

effected supplement and long-term stability data of first three

production batches reported in annual report.

ii. In Vitro Release Documentation

The in vitro release rate of a lot of the dosage form prepared by the

new/modified process should be compared with the in vitro release

rate of a recent lot of comparable age of the dosage form prepared

by the prechange process. The median in vitro release rates (as

estimated by the estimated slope from each cell, see VII) of the lots

prepared by the two processes should be demonstrated to be within

acceptable limits, using the testing procedure described in section

VII (IN VITRO RELEASE TEST) below.

iii. In Vivo Bioequivalence Documentation

None.

c. Filing Documentation

Changes being effected supplement (all information including accelerated

stability data); annual report (long-term stability data).

3. Level 3 Change

No level 3 changes are anticipated in this category.
14

V. BATCH SIZE (SCALE-UP/SCALE-DOWN)

This guidance recommends that the minimum batch size for the NDA pivotal clinical trial batch or

the ANDA/AADA biobatch be at least 100 kg or 10% of a production batch, whichever is larger. 

Deviations from this recommendation should be discussed with the appropriate agency review

division. All scale changes should be properly validated and may be inspected by appropriate

agency personnel.

A. Level 1 Change

1. Definition of Level

Change in batch size, up to and including a factor of ten times the size of the 

pivotal clinical trial/biobatch, where: (1) the equipment used to produce the test

batch(es) are of the same design and operating principles; (2) the batch(es) is

manufactured in full compliance with cGMPs; and (3) the same standard operating

procedures (SOPs) and controls, as well as the same formulation and

manufacturing procedures, are used on the test batch(es) and on the full-scale

production batch(es).

2. Test Documentation

a. Chemistry Documentation

Application/compendial product release requirements. Notification of

change and submission of updated executed batch records in annual report. 

Stability testing: First production batch on long-term stability reported in

annual report.

b. In Vitro Release Documentation

None.

c. In Vivo Bioequivalence Documentation

None.

3. Filing Documentation

Annual report (all information including long-term stability data).

B. Level 2 Change
15

1. Definition of Level

Changes in batch size from beyond a factor of ten times the size of the pivotal

clinical trial/biobatch, where: (1) the equipment used to produce the test batch(es)

are of the same design and operating principles; (2) the batch(es) is manufactured

in full compliance with cGMPs; and (3) the same standard operating procedures

(SOPs) and controls, as well as the same formulation and manufacturing

procedures, are used on the test batch(es) and on the full-scale production

batch(es).

2. Test Documentation

a. Chemistry Documentation

Application/compendial product release requirements. Notification of

change and submission of updated executed batch records.

Stability testing: One batch with three months accelerated stability data

reported in changes being effected supplement and long-term stability data

of first production batch reported in annual report.

b. In Vitro Release Documentation

The in vitro release rate of a lot of the scaled-up batch should be compared

with the in vitro release rate of a recent lot, of comparable age, of the

prechange scale. The median in vitro release rates (as estimated by the

estimated slope from each cell, see section VII) of the lots of the two scales

should be demonstrated to be within acceptable limits, using the testing

procedure described in section VII (IN VITRO RELEASE TEST) below.

c. In Vivo Bioequivalence Documentation

None.

3. Filing Documentation

Changes being effected supplement (all information including accelerated stability

data); annual report (long-term stability data).

C. Level 3 Change

No level 3 changes are anticipated in this category.
16

VI. MANUFACTURING SITE 

Manufacturing site changes consist of changes in location in the site of manufacture,

packaging/filling operations, and/or testing for both company owned and contract manufacturing

facilities and do not include any other level 2 or 3 changes, e.g., changes in scale, manufacturing

(including process and/or equipment), and components or composition. New manufacturing

locations should have had a satisfactory cGMP inspection within the past two years. 

A stand-alone analytical testing laboratory site change may be submitted as a changes being

effected supplement if the new facility has a current and satisfactory cGMP compliance profile

with FDA for the type of testing operation in question. The supplement should contain a

commitment to use the same test methods employed in the approved application, written

certification from the testing laboratory stating that they are in conformance with cGMPs, and a

full description of the testing to be performed by the testing lab. If the facility has not received a

satisfactory cGMP inspection for the type of testing involved, a prior approval supplement is

recommended. No stability data are needed for a change in a stand alone analytical facility.
17

A. Level 1 Change

1. Definition of Level

Level 1 changes consist of site changes within a single facility where the same

equipment, standard operating procedures (SOPs), environmental conditions (e.g.,

temperature and humidity) and controls, and personnel common to both

manufacturing sites are used, and where no changes are made to the manufacturing

batch records, except for administrative information and the location of the facility. 

Common is defined as employees already working on the campus who have

suitable experience with the manufacturing process.

2. Test Documentation

a. Chemistry Documentation 

None beyond application/compendial product release requirements.

b. In Vitro Release Documentation

None.

c. In Vivo Bioequivalence Documentation

None.

3. Filing Documentation

Annual report.

B. Level 2 Change

1. Definition of Level

Level 2 changes consist of site changes within a contiguous campus, or between

facilities in adjacent city blocks, where similar equipment, standard operating

procedures, (SOPs), environmental conditions (e.g., temperature and humidity)

and controls, and personnel common to both manufacturing sites are used, and

where no changes are made to the manufacturing batch records, except for

administrative information and the location of the facility.

2. Test Documentation
18

a. Chemistry Documentation

Location of new site and updated executed batch records. None beyond

application/compendial product release requirements.

Stability testing: First production batch on long-term stability reported in

annual report.

b. In Vitro Release Documentation

None.

c. In Vivo Bioequivalence Documentation

None.

3. Filing Documentation

Changes being effected supplement; annual report (long-term stability data).

C. Level 3 Change

1. Definition of Level

Level 3 changes consist of a site change in manufacturing site to a different

campus. A different campus is defined as one that is not on the same original

contiguous site or where the facilities are not in adjacent city blocks. To qualify as

a Level 3 change, similar equipment, SOPs, environmental conditions, and controls

should be used in the manufacturing process at the new site. Changes should not

be made to the manufacturing batch records except when consistent with other

level 1 changes. Administrative information, location, and language translation may

be revised as needed.

Any change to a new contract manufacturer also constitutes a level 3 change.

2. Test Documentation

a. Chemistry Documentation

Location of new site and updated executed batch records. 

Application/compendial product release requirements.
19

Significant body of information available: One batch with three months

accelerated stability data reported in changes being effected supplement

and long-term stability data of first three production batches reported in

annual report.

Significant body of information not available: Three batches with three

months accelerated stability data reported in changes being effected

supplement and long-term stability data of first three production batches

reported in annual report.

b. In Vitro Release Documentation

The in vitro release rate of a lot of the dosage form from the new

manufacturing site should be compared with the in vitro release rate of a

recent lot of comparable age of the dosage form manufactured at the prior

site. The median in vitro release rates (as estimated by the estimated slope

from each cell, see section VII) of the lots from the two sites should be

demonstrated

to be within

acceptable

limits, using

the testing

procedure

described in

section VII

(IN VITRO

RELEASE

TEST) below.

c. In Vivo Bioequivalence Documentation

None.

3. Filing Documentation

Changes being effected supplement (all information including accelerated stability

data); annual report (long-term stability data).

VII. IN VITRO RELEASE TEST

In vitro release is one of several standard methods which can be used to characterize performance

characteristics of a finished topical dosage form, i.e., semisolids such as creams, gels, and
20

ointments. Important changes in the characteristics of a drug product formula or the

thermodynamic properties of the drug(s) it contains should show up as a difference in drug

release. Release is theoretically proportional to the square root of time (/t) when the formulation

in question is in control of the release process because the release is from a receding boundary.

In vitro release method for topical dosage forms is based on an open chamber diffusion cell

system such as a Franz cell system, fitted usually with a synthetic membrane. The test product is

placed on the upper side of the membrane in the open donor chamber of the diffusion cell and a

sampling fluid is placed on the other side of the membrane in a receptor cell. Diffusion of drug

from the topical product to and across the membrane is monitored by assay of sequentially

collected samples of the receptor fluid. The in vitro release methodology should be appropriately

validated. Sample collection can be automated.

Aliquots removed from the receptor phase can be analyzed for drug content by high pressure

liquid chromatography (HPLC) or other analytical methodology. A plot of the amount of drug

released per unit area (mcg/cm ) against the square root of time yields a straight line, the slope of 2

which represents the release rate. This release rate measure is formulation-specific and can be

used to monitor product quality. The release rate of the biobatch or currently manufactured

batch should be compared with the release rate of the product prepared after a change as defined

in this guidance.

One possible in vitro release study design is summarized below. Sponsors are encouraged to

review the reference articles listed here.

Diffusion Cell System:

! A diffusion cell system with a standard open cap ground glass surface with 15 mm

diameter orifice and total diameter of 25 mm.

Synthetic Membrane:

! Appropriate inert and commercially available synthetic membranes such as polysulfone,

cellulose acetate/nitrate mixed ester, or Polytetrafluoroethylene 70 Fm membrane of

appropriate size to fit the diffusion cell diameter (e.g., 25 mm in above case).

Receptor Medium:

! Appropriate receptor medium such as aqueous buffer for water soluble drugs or a hydroalcoholic medium for sparingly water soluble drugs or another medium with proper

justification.

Number of Samples:
21

! Multiple replicates (six samples are recommended) to determine the release rate (profile)

of the topical dermatological product.

Sample Applications:

! About 300 mg of the semisolid preparation is placed uniformly on the membrane and kept

occluded to prevent solvent evaporation and compositional changes. This corresponds to

an infinite dose condition.

Sampling Time:

! Multiple sampling times (at least 5 times) over an appropriate time period to generate an

adequate release profile and to determine the drug release rate (a 6-hour study period with

not less than five samples, i.e., at 30 minutes, 1, 2, 4 and 6 hours) are suggested. The

sampling times may have to be varied depending on the formulation. An aliquot of the

receptor phase is removed at each sampling interval and replaced with fresh aliquot, so

that the lower surface of the membrane remains in contact with the receptor phase over

the experimental time period.

Sample Analysis:

! Appropriate validated specific and sensitive analytical procedure should be used to analyze

the samples and to determine the drug concentration and the amount of drug released.

In Vitro Release Rate:

! A plot of the amount of drug released per unit membrane area (mcg/cm ) versus square 2

root of time should yield a straight line. The slope of the line (regression) represents the

release rate of the product. An X intercept typically corresponding to a small fraction of

an hour is a normal characteristic of such plots.

Design of the Rate (Profile) Comparison Study:

! The typical in vitro release testing apparatus has six cells. For each run of the apparatus,

the two products being compared should be assigned to the six cells as follows:

±T ±R ±T

±R ±T ±R

or
22

±R ±T ±R

±T ±R ±T

where T represents the Postchange Lot (Test product) and R represents the Prechange

Lot (Reference product). This approach of including both products in each run of the in

vitro apparatus will help ensure an unbiased comparison in the event of a systematic

difference between runs.

! The choice of the assignment of products to cells (i.e., whether the prechange lot or the

postchange lot is assigned to the “upper left corner cell” of the apparatus) may either be

made systematically (i.e., alternate the pattern for each successive run) or randomly (i.e.,

flip a coin or use some other random mechanism).

! For the case of a nonstandard apparatus, with other than six cells, the principle of

including both the prechange lot and the postchange lot in the same run should still be

used. If the apparatus has only a single cell, the runs on the prechange and postchange

lots should be intermixed, rather than obtaining all observations on one product followed

by all observations on the other product.

Details of the In Vitro Release Comparison Test

! The in vitro release comparison should be carried out as a two-stage test. 

At the first stage, two runs of the (six cells) in vitro apparatus should be carried out,

yielding six slopes (estimated in vitro release rates) for the prechange lot (R) and six

slopes for the postchange lot (T). A 90% confidence interval (to be described below) for

the ratio of the median in vitro release rate (in the population) for the postchange lot over

the median in vitro release rate (in the population) for the prechange lot should be

computed, expressed in percentage terms. If, at the first stage, this 90% confidence

interval falls within the limits of 75% to 133.33%, no further in vitro testing is necessary.

If the test is not passed at the first stage, 4 additional runs of the (six cells) in vitro

apparatus should be carried out, yielding 12 additional slopes for each product, or 18 in all

(including the first-stage results). The 90% confidence interval (to be described below)

should be computed using all 18 slopes for each product, including the first-stage results. 

At the second stage, this 90% confidence interval should fall within the limits of 75% to

133.33%.

Computation of Confidence Interval - an Example:
23

! Because outliers are expected to occur on occasion with this testing (for example, due to

an air bubble between the product sample and the membrane), a nonparametric 

method is proposed, whose performance tends to be resistant to the presence of outliers. 

The computations are illustrated in the following example:

Suppose that the slope data obtained at the first stage are as follows:

Postchange Prechange

Lot (T) Lot (R) 

 1.3390 1.1331

 1.3496 1.1842

 1.4946 1.0824

 1.4668 1.3049

 1.1911 1.0410

 1.2210 1.2419

The first step in the computation of the confidence interval is to form the 36 (= 6 x 6)

individual T/R ratios. This is illustrated in the following table, where the prechange lot

slopes (R) are listed across the top of the table, the postchange lot slopes (T) are listed

down the left margin of the table, and the individual T/R ratios are the entries in the body

of the table:

1.1331 1.1842 1.0824 1.3049 1.0410 1.2419

1.3390 1.1817 1.1307 1.2371 1.0261 1.2863 1.0782

1.3496 1.1911 1.1397 1.2469 1.0343 1.2964 1.0867

1.4946 1.3190 1.2621 1.3808 1.1454 1.4357 1.2035

1.4668 1.2945 1.2386 1.3551 1.1241 1.4090 1.1811

1.1911 1.0512 1.0058 1.1004 0.9128 1.1442 0.9591

1.2210 1.0776 1.0311 1.1280 0.9357 1.1729 0.9832

The second step in the computation of the confidence interval is to order these 36

individual T/R ratios from lowest to highest:

0.9128 0.9357 0.9591 0.9832 1.0058 1.0261 1.0311 1.0343 . . . 1.2863 1.2945
24

1.2964 1.3190 1.3551 1.3808 1.4090 1.4357.

In the third step, the eighth and twenty-ninth ordered individual ratios are the lower and

upper limits, respectively, of the 90% confidence interval for the ratio of the median in

vitro release rate (slope) for T over the median in vitro release rate for R. In the example,

this confidence interval is 1.0343 to 1.2863, or in percentage terms,

103.43% to 128.63%.

Because this confidence interval falls within the limits of 75% to 133.33%, the product

passes at the first stage.

If the product had not passed at the first stage, an additional 4 runs would have been

carried out, yielding 12 additional slopes per lot, for a total of 18 slopes per lot altogether

(including the first-stage slopes).

All 324 ( = 18 x 18) individual T/R ratios would be obtained, and these would be ranked

from lowest to highest. It should be evident that even the computations at the first stage

would be tedious to do by hand, and doing the computations at the second stage by hand

is infeasible. A computer should be used.

At the second stage, the 110th and the 215th ordered individual ratios are the lower and

upper limits, respectively, of the 90% confidence interval for the ratio of the median in

vitro release rate (slope) for T over the median in vitro release rate for R. If this

confidence interval falls within the limits of 75% to 133.33%, the product passes the test

at the second stage.

Further Remarks on the In Vitro Release Comparison Test

! The statistical test described above is based on a standard confidence interval procedure

related to the Wilcoxon Rank Sum/Mann-Whitney rank test, applied to the log slopes. 

References to this confidence interval procedure include:

Conover, W.J., Practical Nonparametric Statistics (Second Edition), John Wiley & Sons,

page 223ff, 1980.

Hollander, M. and D.A.Wolfe, Nonparametric Statistical Methods, John Wiley & Sons,

page 78ff, 1973.

However, as was seen in the example, it is not necessary to actually compute logs in order

to carry out the test.

! The example illustrates the case of full data, i.e., where there are 6 slopes per lot at the
25

first stage and, if the second stage is necessary, 18 slopes per lot at the second stage. If

slopes are missing, the computations will need to be modified. For example, if a single

slope were missing from one of the lots (it does not matter if it is the prechange lot or the

postchange lot) at the first stage, there would only be 30 (= 5 x 6) individual T/R ratios,

and the limits of the 90% confidence interval would no longer be the eighth and twentyninth ordered individual T/R ratio, but rather would be the sixth and twenty-fifth ordered

individual T/R ratio. If data are missing at either stage of the test, the correct computation

should be determined either by reference to a statistical text or consultant, or by

consultation with CDER staff.

! The statistical procedure as described above does not take the block structure of the test

(i.e., the fact that data are obtained in runs of six slopes at a time, rather than all at once)

into account. This is justified by the following:

1. In vitro release data available to the Center at this time show no evidence of an

important run-to-run effect.

2. The proposed experimental design, in which both products are included in each

run, will help to ensure unbiasedness if a run-to-run effect should occur.

VIII. IN VIVO BIOEQUIVALENCE STUDIES

The design of in vivo bioequivalence studies for semisolid dosage forms varies depending on the

pharmacological activity of the drug and dosage form. A brief general discussion of such tests

follows. 

Objective:

To document the bioequivalence of the drug product for which the manufacture has been

changed, as defined in this guidance, compared to the drug product manufactured prior to the

change or compared to the reference listed drug (RLD). 

Design:

The study design is dependent on the nature of the active drug. The bioequivalence study can be

a comparative skin blanching study as in glucocorticoids (FDA, Topical Dermatological

Corticosteroids: In Vivo Bioequivalence, June 2, 1995.) or a comparative clinical trial or any

other appropriate validated bioequivalence study (e.g., dermatopharmacokinetic study) for the

topical dermatological drug product.

Analytical Method:

The assay methodology selected should ensure specificity, accuracy, interday and intraday

precision, linearity of standard curves, and adequate sensitivity, recovery, and stability of the

samples under the storage and handling conditions associated with the analytical method.
 See Workshop Report: Scale-up of liquid and semi-solids disperse systems. G. A. Van Buskirk, V. P. Shah, D. 3

Adair, et al. Pharmaceutical Research, 11, 1216-1220, 1994, 

26

GLOSSARY OF TERMS3

Approved Target Composition: The components and amount of each ingredient for a drug

product used in an approved pivotal clinical study or bioequivalence study.

Batch: A specific quantity of a drug or other material produced according to a single

manufacturing order during the same cycle of manufacture and intended to have uniform character

and quality, within specified limits. (21 CFR 210.3(b)(2)).

Contiguous Campus: Contiguous or unbroken site or a set of buildings in adjacent city blocks.

Creams/Lotions: Semisolid emulsions that contain fully dissolved or suspended drug substances

for external application. Lotions are generally of lower viscosity.

Diluent: A vehicle in a pharmaceutical formulation commonly used for making up volume and/or

weight (e.g., water, paraffin base).

Drug Product: A drug product is a finished dosage form (e.g., cream, gel, or ointment) in its

marketed package. It also can be a finished dosage form (e.g., tablet, capsule, or solution) that

contains a drug substance, generally, but not necessarily, in association with one or more other

ingredients (21 CFR 314.3(b)). 

Drug Release: The disassociation of a drug from its formulation thereby allowing the drug to be

distributed into the skin or be absorbed into the body where it may exert its pharmacological

effect.

Drug Substance: An active ingredient that is intended to furnish pharmacological activity or

other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of a disease, or to

affect the structure or any function of the human body, but does not include intermediates used in

the synthesis of such ingredient (21 CFR 314.3(b)).

Emulsion: Emulsions are two phase systems in which an immiscible liquid (dispersed phase) is

dispersed throughout another liquid (continuous phase or external phase) as small droplets. 

Where oil is the dispersed phase and an aqueous solution is the continuous phase, the system is

designated as an oil-in-water emulsion. Conversely, where water or an aqueous solution is the

dispersed phase and oil or oleaginous material is the continuous phase, the system is designated as

a water-in-oil emulsion. Emulsions are stabilized by emulsifying agents that prevent coalescence,

the merging of small droplets into larger droplets and, ultimately, into a single separated phase. 

Emulsifying agents (surfactants) do this by concentration in the interface between the droplet and

external phase and by providing a physical barrier around the particle to coalesce. Surfactants

also reduce the interfacial tension between the phases, thus increasing the ease of emulsification

upon mixing. Emulsifying agents substantially prevent or delay the time needed for emulsion
27

droplets to coalesce. Emulsification is the act of forming an emulsion. Emulsification can involve

the incorporation of a liquid within another liquid to form an emulsion or a gas in a liquid to form

a foam.

Formulation: A listing of the ingredients and quantitative composition of the dosage form.

Gel: A semisolid system in which a liquid phase is constrained within a three dimensional, crosslinked matrix. The drug substance may be either dissolved or suspended within the liquid phase.

Homogenization: A method of atomization and thereby emulsification of one liquid in another in

which the liquids are pressed between a finely ground valve and seat under high pressure (e.g., up

to 5,000 psi).

Internal phase: The internal phase or the dispersed phase of an emulsion comprises the droplets

that are found in the emulsion.

In Vitro Release Rate: Rate of release of the active drug from its formulation, generally

expressed as amount/unit area/time .

0.5

Ointment: An unctuous semisolid for topical application. Typical ointments are based on

petrolatum. An ointment does not contain sufficient water to separate into a second phase at

room temperature. Water soluble ointments may be formulated with polyethylene glycol.

Pilot Scale Batch: The manufacture of drug product by a procedure fully representative of and

simulating that intended to be used for full manufacturing scale.

Preservative: An agent that prevents or inhibits microbial growth in a formulation to which it

has been added.

Process: A series of operations, actions and controls used to manufacture a drug product.

Scale-up: The process of increasing the batch size.

Scale-down: The process of decreasing the batch size.

Shear: A strain resulting from applied forces that cause or tend to cause contiguous parts of a

body to slide relative to one another in direction parallel to their plane of contact. In

emulsification and suspensions, the strain produced upon passing a system through a homogenizer

or other milling device.

! Low shear: Processing in which the strain produced through mixing and/or emulsifying

shear is modest.
28

! High shear: Forceful processes which, at point of mixing or emulsification place a great

strain on the product. Homogenization, by its very nature, is a high shear process which

leads to a small and relatively uniform emulsion droplet size. Depending on their

operation, mills and mixers are categorized as either high shear or low shear devices.

Significant Body of Information: A significant body of information on the stability of the

product is likely to exist after five years of commercial experience for new molecular entities , or

three years of commercial experience for new dosage forms.

Structure Forming Excipient: An excipient which participates in the formation of the

structural matrix which gives an ointment, cream or gel etc., its semisolid character. Examples

are gel forming polymers, petrolatum, certain colloidal inorganic solids (e.g., bentonite), waxy

solids (e.g., cetyl alcohol, stearic acid), and emulsifiers used in creams.

Strength: Strength is the concentration of the drug substance (for example, weight/weight,

weight/volume, or unit dose/volume basis), and/or the potency, that is, the therapeutic activity of

the drug product as indicated by appropriate laboratory tests or by adequately developed and

controlled clinical data (expressed, for example, in terms of units by reference to a standard) (21

CFR 210.3(b)(16)). For semisolid dosage forms the strength is usually stated as a weight/weight

(w/w) or weight/volume (w/v) percentage.

Suspending agent: An excipient added to a suspension to control the rate of sedimentation of

the active ingredients.

Technical grade: Technical grades of excipients differ in their specifications and intended use. 

Technical grades may differ in: (1) specifications and/or functionality, (2) impurities, and

(3) impurity profiles.

Validation: A procedure to establish documented evidence that provides a high degree of

assurance that a specific process or test will consistently produce a product or test outcome

meeting its predetermined specifications and quality attributes. A validated manufacturing

process or test is one that has been proven to do what it purports or is represented to do. The

proof of process validation is obtained through collection and evaluation of data, preferably

beginning with the process development phase and continuing through the production phase.

Process validation necessarily includes process qualification (the qualification of materials,

equipment, systems, building, personnel), but it also includes the control of the entire processes

for repeated batches or runs.
29

REFERENCES

1. Shah, V. P., J. Elkins, J. Hanus, C. Noorizadeh, and J. P. Skelly,"In Vitro Release of

Hydrocortisone from Topical Preparations and Automated Procedure," Pharmaceutical

Research, 8:55-59, 1991.

2. Shah, V. P., J. S. Elkins, and R. L. Williams, "In Vitro Drug Release Measurement of

Topical Glucocorticoid Creams," Pharmacopeial Forum, 19, 5048-5059, 1993.

3. Corbo, M., T. W. Schultz, G. K. Wong, and G. A. Van Buskirk, "Development and

Validation of In Vitro Release Testing Methods for Semisolid Formulations," 

Pharmaceutical Technology 17(9):112-128, 1993.

4. Li, J. B. and P. C. Rahn, "Automated Dissolution Testing of Topical Drug Formulations

Using Franz Cells and HPLC Analysis," Pharmaceutical Technology 17(7):44-52, 1993.

5. Shah, V. P. and J. S. Elkins, "In Vitro Release from Corticosteroid Ointments," 

Journal of Pharmaceutical Sciences, 84:1139-1140, 1995.

6. Zatz, J.L., "Drug Release from Semisolids: Effect of Membrane Permeability on

Sensitivity to Product Parameters," Pharmaceutical Research 2:787-789, 1995.
30

Table 1 - Components and Composition

Level Change Test Documentation Filing Documentation

1 C Deletion or partial deletion of color, C Application/compendial product C Annual report (all information

fragrance, or flavor release requirements including long-term stability data)

C Up to 5% change in approved amount of C Stability: First production batch on

an excipient with the total additive effect long-term stability

of all excipient changes #5%

C Supplier of structure forming excipient

that is primarily a single chemical entity

(purity $ 95%) or change in supplier or

technical grade of any other excipient

2 C Change of >5% and #10% of approved C Application/compendial product C Changes being effected supplement

amount of an excipient with the total release requirements (all information including accelerated

additive effect of all excipient changes stability data)

#10% C Executed batch records

C Change in supplier of a structure forming C Stability: One batch with three data)

excipient (not covered under level 1) months accelerated stability data and

C Change in technical grade of a structure stability

forming excipient

C Change in particle size distribution of the

drug substance, if the drug is in

suspension

first production batch on long-term

C In vitro release test

C Annual report (long-term stability
31

Table 1 - Components and Composition (cont.)

Level Change Test Documentation Filing Documentation

3 C Any qualitative and quantitative changes C Application/compendial product C Prior approval supplement (all

in an excipient beyond the ranges noted release requirements information including accelerated

in level 2 change stability data)

C Change in crystalline form of the drug C Annual report (long-term stability

substance, if the drug is in suspension C Stability: data)

C Executed batch records

Significant body of information

available: One batch with three

months accelerated stability data and

first three production batches on longterm stability. 

Significant body of information not

available: Three batches with three

months accelerated stability data and

first three production batches on longterm stability 

C In vitro release test (encouraged only)

• In vivo bioequivalence test

Note: See text for additional information.
32

Table 2 - Components and Composition - Preservative

Level Change Test Documentation Filing Documentation

1 C Quantitatively 10% or less change in C Application/compendial product release C Annual report

the approved amount of preservative requirements

C Preservative effectiveness test at lowest

specified preservative level

2 C Quantitatively greater than 10% and C Application/compendial product release C Changes being effected

up to 20% change in the approved requirements supplement

amount of preservative

C Preservative effectiveness test at lowest

specified preservative level

3 C Quantitatively greater than 20% C Application/compendial product release C Prior approval supplement (all

change in the approved amount of requirements information including

preservative (including deletion) or accelerated stability data)

use of a different preservative C Executed batch records

C Preservative effectiveness test at lowest stability data)

specified preservative level

C For new preservative: analytical method

for identification and assay; validation

studies showing new preservative does not

interfere with application/compendial tests

C Stability: One batch with three months

accelerated stability data and first

production batch on long-term stability

C Annual report (long-term

Note: See text for additional information.
33

Table 3 - Manufacturing Equipment

Level Change Test Documentation Filing Documentation

1 C Nonautomated or nonmechanical C Application/compendial product C Annual report (all information

equipment to automated or release requirements including long-term stability)

mechanical equipment to transfer

ingredients C Stability: First production batch on

C Alternative equipment of same design

and operating principles

long-term stability

2 C Equipment of a different design or C Application/compendial product C Changes being effected supplement

different operating principles release requirements (all information including

C Type of mixing equipment: e.g., high C Executed batch record

shear to low shear or vice versa. C Annual report (long-term stability

C Stability: data)

Significant body of information 

available: One batch with three months

accelerated stability data and first

production batch on long-term

stability. 

Significant body of information not

available: Three batches with three

months accelerated stability data and

first three production batches on longterm stability.

C In vitro release test

accelerated stability data)

Note: See text for additional information.
34

Table 4 - Manufacturing Process

Level Change Test Documentation Filing Documentation

1 C Process changes within approved C Application/compendial product release C Annual report

applications ranges requirements

C Order of addition of components

(excluding actives)

2 C Process changes outside approved C Application/compendial product release C Changes being effected supplement

application ranges requirements (all information including accelerated

C Process of combining phases C Executed batch record

C Annual report (long-term stability

C Stability: data)

Significant body of information

available: One batch with three months

accelerated stability data and first

production batch on long-term stability. 

Significant body of information not

available: Three batches with three

months accelerated stability data and

first three production batches on longterm stability.

C In vitro release test

stability data)

Note: See text for additional information.
35

Table 5 - Batch Size

Level Change Test Documentation Filing Documentation

1 C Change in batch size up to and C Application/compendial product release C Annual report (all information

including ten times the size of the requirements including long-term stability data)

pivotal clinical trial/biobatch

C Executed batch records

C Stability: First production batch on

long-term stability

2 C Change in batch size beyond a factor C Application/compendial product release C Changes being effected supplement

of ten times the size of the pivotal requirements (all information including

clinical trial/biobatch accelerated stability data)

C Executed batch records

C Stability: One batch with three months data)

accelerated stability data and first

production batch on long-term stability 

C In vitro release test

C Annual report (long-term stability

Note: See text for additional information. 
36

Table 6 - Manufacturing Site Change

Level Change Test Documentation Filing Documentation

1 C Within a single facility C Application/compendial product release C Annual report

requirements

2 C Within the same contiguous C Application/compendial product release C Changes being effected supplement

campus or between facilities in requirements

adjacent city blocks C Annual report (long-term stability

C Executed batch records data)

C Location of new site

C Stability: First production batch on longterm stability

3 C Different campus C Application/compendial product release C Changes being effected supplement

C Contract manufacturer stability data)

requirements (all information including accelerated

C Executed batch record

C Location of new site data)

C Stability

Significant body of information available:

One batch with three months accelerated

stability data and first three production

batches on long-term stability. 

Significant body of information not

available: Three batches with three months

accelerated stability data and first three

production batches on long-term stability.

C In vitro release test

C Annual report (long-term stability

Note: See text for additional information. 
37

COMIS # 

Created: VShah:1996

Reviewed: KRoberts: January 1997

Edited: VShah: May 7, 1997

Reviewed: NSager: May 12, 1997

Proofed: OVieira: May 14, 1997

Reviewed: JAxelrad: May 19, 1997

Changes: NDerr: May 21, 1997

Final Review: VShah: May 21, 1997

Final proof: NDerr:May 21, 1997