Size, Shape, and Other 
Physical Attributes of 
Generic  
Tablets and Capsules 
 
Guidance for Industry 
 
 
 
 
 
  
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Drug Evaluation and Research (CDER) 
 
October 2022 
Pharmaceutical Quality/CMC 
 
Revision 1
 
 
 
   
Size, Shape, and Other 
Physical Attributes of 
Generic Tablets and 
Capsules 
 
Guidance for Industry 
 
 
Additional copies are available from: 
Office of Communications, Division of Drug Information  
Center for Drug Evaluation and Research 
Food and Drug Administration 
10001 New Hampshire Ave., Hillandale Bldg., 4th Floor  
Silver Spring, MD 20993-0002  
Phone: 855-543-3784 or 301-796-3400; Fax: 301-431-6353 
Email: druginfo@fda.hhs.gov  
https://www.fda.gov/drugs/guidance-compliance-regulatory-information/guidances-drugs 
 
 
 
 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Drug Evaluation and Research (CDER) 
 
October 2022 
Pharmaceutical Quality/CMC 
 
Revision 1
  Contains Nonbinding Recommendations 
 
TABLE OF CONTENTS 
 
 
 
I.  INTRODUCTION............................................................................................................. 1 
II.  BACKGROUND ............................................................................................................... 2 
A.  Differences in Size and Shape of Tablets and Capsules between a Reference Listed Drug 
and a Drug Product Subject to an Abbreviated New Drug Application ........................................... 2 
1. Size ................................................................................................................................................... 2 
2. Shape ................................................................................................................................................ 3 
3. Patient Factors ................................................................................................................................ 4 
B.  Other Physical Attribute Considerations .................................................................................... 4 
III.  RECOMMENDATIONS .................................................................................................. 4 
A.  Size................................................................................................................................................... 4 
B.  Shape ............................................................................................................................................... 5 
C.  Other Physical Attributes .............................................................................................................. 6 
D.  Biowaivers ....................................................................................................................................... 6 
  Contains Nonbinding Recommendations 
Size, Shape, and Other Physical Attributes of Generic  
Tablets and Capsules  
Guidance for Industry1 
 
 
 
This guidance represents the current thinking of the Food and Drug Administration (FDA or Agency) on 
this topic.  It does not establish any rights for any person and is not binding on FDA or the public.  You 
can use an alternative approach if it satisfies the requirements of the applicable statutes and regulations.  
To discuss an alternative approach, contact the FDA office responsible for this guidance as listed on the 
title page. 
 
 
 
 
I.  INTRODUCTION 
 
Tablets and capsules are widely manufactured and prescribed and may provide a number of 
advantages over other dosage forms, including ease of storage, portability, ease of 
administration, and accuracy in dosing.   
 
While generic formulations of these drug products are required to be both pharmaceutically and 
therapeutically equivalent to a reference listed drug (RLD),2 we are concerned that differences in 
physical characteristics (e.g., size and shape of the tablet or capsule) may affect patient 
compliance and acceptability of medication regimens or could lead to medication errors.  We 
believe these patient safety concerns are important, and we are recommending that generic drug 
manufacturers consider physical attributes when they develop quality target product profiles 
(QTPPs) for their generic product candidates. 
 
The recommendations in this guidance apply to abbreviated new drug applications (ANDAs) and 
their supplements for additional strengths that are submitted to the Office of Generic Drugs 
(OGD).  
 
This guidance does not apply to approved ANDAs (generic drugs) already on the market.3 
However, if the Agency determines that an approved product should be modified because the 
 
1 This guidance has been prepared by the Office of Generic Drugs and the Office of Pharmaceutical Quality in the 
Center for Drug Evaluation and Research at the Food and Drug Administration. 
2 Reference listed drug means the listed drug identified by FDA as the drug product upon which an applicant relies 
in seeking approval of its ANDA.  See 21 CFR 314.3(b).  FDA publishes the identification of RLDs in the Approved 
Drug Products with Therapeutic Equivalence Evaluations (i.e., Orange Book), available at 
https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-
evaluations-orange-book. 
3 If the manufacturer of an RLD makes a postapproval change to the size or shape of a previously approved tablet or 
capsule, the generic versions generally will not need to be modified.  However, the Agency could ask for 
modifications to the product if there are safety concerns because of the differences in physical characteristics. 
 
  
  1  Contains Nonbinding Recommendations 
size or shape of a product poses a risk to public health, we will notify the holder of the ANDA. 
This guidance is not intended to apply to other oral dosage forms (e.g., chewable tablets, oral 
tablets for suspension/solution, orally disintegrating tablets, sublingual tablets, troches, gums). 
 
This guidance revises the guidance of the same name issued in June 2015 to clarify that the 
largest dimension of a tablet should not exceed 22 mm and that capsules should not exceed a 
standard 00 size. This guidance also includes updated references. 
 
In general, FDAs guidance documents do not establish legally enforceable responsibilities.  
Instead, guidances describe the Agencys current thinking on a topic and should be viewed only 
as recommendations, unless specific regulatory or statutory requirements are cited.  The use of 
the word should in Agency guidances means that something is suggested or recommended, but 
not required.  
 
II.  BACKGROUND   
 
A.  Differences in Size and Shape of Tablets and Capsules between a Reference 
Listed Drug and a Drug Product Subject to an Abbreviated New Drug 
Application  
 
1.  Size 
 
Difficulty swallowing tablets and capsules can be a problem for many individuals and can lead to 
a variety of adverse events and patient noncompliance with treatment regimens.  It is estimated 
that over 16 million people in the United States have some difficulty swallowing, also known as 
dysphagia.4,5  For these individuals, swallowing a tablet or a capsule can be particularly 
challenging.  A survey of adults on difficulties swallowing tablets and capsules suggests that this 
problem goes well beyond the patient population with clinically recognized dysphagia and may 
affect as many as 40 percent of Americans.  Of those who experience difficulty swallowing 
medications, less than a quarter discuss the problem with a health care professional, 8 percent 
admit to skipping a dose of prescribed medication, and 4 percent have discontinued therapy 
because the tablets and/or capsules were difficult to swallow.6  Individuals who find it difficult to 
swallow tablets and capsules frequently cite the size as the main reason for the difficulty in 
swallowing.7,8   
 
Size and shape of tablets and capsules affect the transit of the product through the pharynx and 
esophagus and may directly affect a patients ability to swallow a particular drug product.  
Larger tablets and capsules have been shown to have a prolonged esophageal transit time.  This 
 
4 Agency for Health Care Policy and Research, 1999, Diagnosis and Treatment of Swallowing Disorders 
(Dysphagia) in Acute-Care Stroke Patients: Summary, Evidence Report/Technology Assessment: Number 8.
 
5 Robbins J, Langmore S, Hind JA, and Erlichman M, 2002, Dysphagia Research in the 21st Century and Beyond: 
Proceedings From Dysphagia Experts Meeting, J Rehabil Res Dev, 39(4):543548. 
6 Harris Interactive Inc., 2003, Pill-Swallowing Problems in America: A National Survey of Adults, New York, NY: 
Harris Interactive Inc. for Schwarz Pharma, 139. 
7 See footnote 4. 
8 Bhosle M, Benner J, DeKoven M, and Shelton J, 2009, Difficult to Swallow: Patient Preferences for Alternative 
Valproate Pharmaceutical Formulations, Patient Prefer Adherence, 3:161171. 
 
  
  2  Contains Nonbinding Recommendations 
can lead to disintegration of the product in the esophagus and/or cause injury to the esophagus, 
resulting in pain and localized esophagitis and the potential for serious sequelae including 
ulceration, stricture, and perforation.9,10  Other adverse events such as pain, gagging, choking, 
and aspiration are related to swallowing difficulties in the oropharyngeal phase of swallowing 
and increasingly occur at larger tablet and capsule sizes.11,12   
 
Studies in adults evaluating the effect of tablet and capsule size on ease of swallowing suggest 
that increases in size are associated with increases in patient complaints related to swallowing 
difficulties at tablet sizes greater than approximately 8 mm in diameter.13,14,15  The size of the 
tablet or capsule influences esophageal transit, irrespective of patient factors and administration 
techniques (i.e., use of fluids, patient position).  Smaller tablets generally have been shown to 
have significantly faster transit times in these studies.  Channer and Virjee specifically compared 
the transit time of 8 mm diameter round tablets to 11 mm diameter round tablets and 14 mm x 9 
mm oval tablets and found the transit times for the 8 mm round tablet to be significantly shorter 
than for 11 mm round and 14 mm x 9 mm oval tablets (p<.02 and p<.04, respectively).16  In 
addition, significantly more patients were aware of the larger round tablets (>8 mm) sticking in 
the esophagus compared with the 8 mm round tablets.17  Although there has been less research 
quantifying the effects of size difference on the oropharyngeal phase of swallowing, increasing 
tablet or capsule size is believed to correlate with increasing difficulty with oropharyngeal 
transfer.   
 
2.  Shape 
 
For any given size, certain shapes may be easier to swallow than others.  In vitro studies suggest 
that flat tablets have greater adherence to the esophagus than capsule-shaped tablets.18  Studies in 
humans have also suggested that oval tablets may be easier to swallow and have faster 
esophageal transit times than round tablets of the same weight.19,20 Patient compliance with 
medication regimens may be influenced by the size and shape of a tablet or capsule.    
 
 
9 Drug and Therapeutics Bulletin, 1981, Tablets and Capsules that Stick in the Oesophagus, Drug Ther Bull, 
19(9):3334. 
10 Channer K and Virjee JP, 1986, The Effect of Size and Shape of Tablets on their Esophageal Transit, J Clin 
Pharmacol, 26(2):141146. 
11 Kelly J, DCruz G, and Wright D, 2010, Patients With Dysphagia: Experiences of Taking Medication, J Adv 
Nurs, 66(1):8291. 
12 Jackson LD, Little J, Kung E, Williams EM, Siemiatkowska K, and Plowman S, 2008, Safe Medication 
Swallowing in Dysphagia: A Collaborative Improvement Project, Healthc Q, 11:110116. 
13 See footnote 10. 
14 Wamberg T, Jorgensen F, Hasselbalch H, and Hey H, 1983, The Prejudgement of the Esophageal Transfer of 
Tablets and Capsules, Archiv der Pharmazie Chemistry in Life Sciences, Ed., 11:2431.  
15 Brotherman DP, Bayraktaroglu TO, and Garofalo RJ, 2004, Comparison of Ease of Swallowing of Dietary 
Supplement Products for Age-Related Eye Disease, J Am Pharm Assoc, 44(5):587593. 
16 See footnote 10. 
17 Ibid. 
18 Marvola M, Rajaniemi M, Marttila E, Vahervuo K, and Sothmann A, 1983, Effect of Dosage Form and 
Formulation Factors on the Adherence of Drugs to the Esophagus, J Pharm Sci, 72(9):10341036.   
19 See footnote 10. 
20 Hey H, Jorgensen F, Sorensen K, Hasselbelch H, and Wamberg T, 1982, Oesophageal Transit of Six Commonly 
Used Tablets and Capsules, Br Med J, 285(6356):17171719. 
 
  
  3  Contains Nonbinding Recommendations 
3.  Patient Factors 
 
The Agency recognizes that a variety of other factors may affect a patients ability to swallow a 
tablet or a capsule.  For example, age could be a factor.  Children and adolescents, as well as the 
elderly, are more likely to have difficulty swallowing tablets or capsules.  Body position, fluid 
intake, and the presence of certain medical conditions (e.g., multiple sclerosis, muscular 
dystrophy, Parkinson's disease) may also affect a patients ability to swallow tablets and 
capsules.  
 
Although not all patient factors can be addressed through pharmaceutical design and 
manufacture, the physical characteristics of a product can be addressed.  These physical 
characteristics influence the ability of certain patients to swallow the product, particularly in 
vulnerable populations.  We believe that tablets and capsules can be effectively developed and 
manufactured to minimize swallowing difficulties, which can encourage and improve patient 
compliance with medication regimens.  FDA recommends that applicants design and develop 
generic drugs with this in mind. 
 
B.  Other Physical Attribute Considerations 
 
The presence and composition of a coating can also potentially affect the ease of swallowing 
tablets or capsules.  The lack of a film coating can decrease or prevent tablet mobility compared 
with a coated tablet of the same size and shape.  Coating also can affect other factors that 
contribute to patient acceptance, such as palatability and smell.   
 
The weight of the tablet or capsule also may affect transit time, with heavier tablets or capsules 
having faster transit times compared to similarly-sized, lighter tablets or capsules.  Surface area, 
disintegration time, and propensity for swelling when swallowed are additional parameters that 
can influence esophageal transit time and have the potential to affect the performance of the drug 
product for its intended use.  These physical attributes should also be considered when 
developing a QTPP for generic drug products intended to be swallowed intact. 
 
III.  RECOMMENDATIONS 
 
The recommendations in this guidance are based on published literature regarding patient 
experiences swallowing tablets and capsules and Agency experience with NDAs and ANDAs 
submitted for oral tablets and capsules.  If a tablet or capsule intended to be swallowed intact 
differs from the criteria recommended in this guidance document, then the applicant should 
contact OGD with supportive information and justification before establishing the QTPP. 
 
A.  Size  
 
For comparable ease of swallowing as well as patient acceptance and compliance with treatment 
regimens, the Agency recommends that generic oral tablets and capsules intended to be 
swallowed intact should be of a similar size to the corresponding RLD. The Agency recommends 
limiting size differences between therapeutically equivalent tablets as follows:  
 
 
  
  4  Contains Nonbinding Recommendations 
  If the RLD is less than 17 mm in its largest dimension,21 the generic product should be:  
  No more than 20 percent larger than the RLD in any single dimension (the 
o
resulting single dimension of the generic should not exceed 17 mm).  
  No more than 40 percent larger than the volume of the RLD.22   
o
 
  If the RLD is equal to or greater than 17 mm in its largest dimension, the generic product 
should be: 
  No larger than the RLD in any single dimension.  
o
  No larger than the volume of the RLD.  
o
 
  We recommend that the largest dimension of a tablet should not exceed 22 mm and that 
capsules should not exceed a standard 00 size.23 
 
Additional flexibility may be given for products that are 8 mm or smaller in their largest 
dimension, but efforts should be made to develop tablets and capsules that are of a similar size 
and shape to the RLD.  
 
Under the standard capsule size convention, the allowances described above will generally allow 
an increase of one capsule size, when the RLD capsule is of size 3 or smaller. When the RLD 
capsule is of size 2 or larger, an increase of one capsule size should only be considered when 
adequate justification can be provided for the size increase. These recommendations would allow 
an increase of one capsule size when the capsule size is less than capsule size 00. 
 
The Agency recognizes that two drug products may have different recommended upper size 
limits, but size should be considered as part of a single product risk/benefit profile. When 
establishing therapeutic equivalence, the applicant should compare their generic product only to 
the RLD.  
 
B.  Shape 
 
In addition to the size recommendations described above, we recommend manufacturing tablets 
and capsules that have a similar shape or have a shape that has been found to be easier to 
swallow compared with the shape of the RLD.  Evaluating and comparing the largest cross 
sectional areas of the RLD and generic product is one strategy to quantify changes in shape.24  
Tablets and capsules that have a larger cross sectional area (e.g., tablets that are rounder) would 
generally be more difficult to swallow than tablets or capsules of the same volume but with 
smaller cross sectional areas. 
 
 
21 The largest dimension refers to the length of oval or capsule shaped tablets or the diameter of round tablets. 
22 For the purposes of this guidance, volume refers to the volume occupied by the tablet or capsule.   
23 An internationally accepted numbering system for capsule sizes is used in approved U.S. drug products.  For the 
purpose of this guidance, a liquid fill capsule is considered a capsule.      
24 For the purposes of this guidance, the largest cross sectional area is defined by the largest cross sectional area of 
the tablet that lies in a plane perpendicular to the longest axis of the tablet.  If the shape of tablet is unconventional 
(e.g., pentagon, triangle, diamond, heart), then the largest cross sectional area will be defined as the area of the 
smallest circle, oval, or ellipse that would completely enclose this largest cross sectional shape.    
 
  
  5  Contains Nonbinding Recommendations 
There are a variety of techniques that may be used to determine the volume measurements of a 
tablet or capsule, including use of pycnometers, or calculations based on physical measurements 
of the tablet or the die used to produce the tablet.  For the purpose of this guidance, spatial 
imaging and/or the use of computer models is recommended, because they are more accurate and 
applicable to a variety of shapes, although other appropriately validated methods may be used if 
properly justified.   
 
The size of a tablet or capsule should be provided in the common technical document (CTD) 
format,25 section 3.2.P.1, Description and Composition of the Drug Product of the ANDA.  Any 
studies and/or related information should be provided in the CTD section, 5.3.1.2, Comparative 
Bioavailability and Bioequivalence Study Reports.  The Agency may request samples for 
evaluation of the physical attributes of a tablet or capsule.   
 
C.  Other Physical Attributes 
 
Other physical attributes of tablets and capsules should be considered in the context of their effect 
on ease of swallowing.  For example, tablet coating, weight, surface area, disintegration time, 
and propensity for swelling should be considered when developing a QTPP for generic tablets.    
 
Description of these physical characteristics should be provided in the CTD section 3.2.P.1, 
Description and Composition of the Drug Product of the ANDA.  A summary of any studies to 
support sizes outside the recommendation provided in this guidance should be provided in the 
CTD section 3.2.P.2, Pharmaceutical Development or CTD section 3.2.P.5.6, Justification of 
Specifications.   
 
D.  Biowaivers 
 
A biowaiver (i.e., the waiver of in vivo bioequivalence data) for additional strengths of a solid 
oral dosage form is generally granted if it meets one of the criteria set forth in the regulations,26 
one of which is proportional similarity between strengths in active and inactive ingredients.  
Compositional proportionality may be particularly relevant when considering tablet size and 
tablet formulation for other strengths (both lower and higher) of the same dosage form to be 
considered for a waiver of the in vivo bioequivalence study requirement. Although 
compositional proportionality may exist when all active and inactive ingredients are in the same 
proportion between different strengths, other methods of achieving compositional proportionality 
may be more amenable to maintaining appropriate tablet sizes for generic products when 
compared with the RLD.  A detailed description of how the Agency defines proportional 
similarity can be found in the draft guidance for industry Bioequivalence Studies With 
Pharmacokinetic Endpoints for Drugs Submitted Under an ANDA (August 2021).27 
 
 
25 See the International Council for Harmonisation (ICH) guidance for industry M4Q: The CTD  Quality (August 
2001). We update guidances periodically. For the most recent version of a guidance, check the FDA guidance web 
page at https://www.fda.gov/regulatory-information/search-fda-guidance-documents. 
26 See 21 CFR 320.22(d). 
27 When final, this guidance will represent the FDAs current thinking on this topic. 
 
  
  6  Contains Nonbinding Recommendations 
FDA recommends that applicants consider Agency published guidance, product specific 
guidance,28 and relevant regulations29 on the waiver process when designing and formulating 
other strengths of the same dosage form that will be studied with bioequivalence studies. For 
specific questions related to biowaivers, you should contact the appropriate review division 
within OGD. 
 
28 Available at https://www.fda.gov/drugs/guidances-drugs/product-specific-guidances-generic-drug-development. 
29 See 21 CFR 320.22. 
 
  
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