Application Note

Rapid formulation screening of biologics withautomated viscometry
Introduction

Materials and methods

Monoclonal antibodies (mAb) are an importantclass of thera­peutic proteins used to treat a variety of diseases, including cancer and autoimmune
conditions. To be effective, many mAb formulations
must have high concentrations (>150 mg/mL mAb).
These high mAb concentrations increase formulation viscosity, which can limit drug delivery options
and complicate manufac­turing. Recent publications
have highlighted the utility of viscometry to predict
the “developability” of protein therapeutics1–2; however, routine viscosity screening of drug candidates
and formulations can be extremely time-consumingwhen using conventional manual techniques.

Measurements using the Kinexus rotationalrheometer were performed according to the
manufacturer’s guidelines. For each measurement,
180 μL of sample was added to the measuring
plate. Viscosities were calculated from multiple
shear stress and shear rates as functions ofmeasurement time. One measurement wasperformed for each sample and required a totalof 30 minutes — 5 minutes for manual cleaningand sample loading followed by a 25 minutemeasurement.
A freeslate jr. with a viscosity station was used forthis study. Prior to running samples, deionized waterand Brix standard solutions were used to calibrate

Unchained Labs’ viscosity station automatesviscosity measurements from start to finish. This
microcapillary viscometer performs accurate andprecise viscosity measurements of Newtonian andnon-Newtonian liquids with small volume requirements (only 100 μL per sample). With this system,
over 200 samples can be analyzed in a single day,with minimal hands-on time. The viscosity station
can be integrated with other analytics such asturbidity, visual particle analysis and pH on thefreeslate jr. or into a customized larger workflow ona freeslate system configured for biologics formulation.

Viscometer comparison
250245

Kinexus rheometer
Unchained Labs viscosity station

210

Viscosity (cP)

200

150

100
5941500

In this application note, we compare the viscometry
results for six mAb formulations (20–200 mg/mL)
measured using Unchained Labs' viscosity station
and a Malvern Kinexus rheometer.

1120

3250

4370

14 10120mAb concentration (mg/mL)

165

200Figure 1: A comparison of the viscosity results of six mAb formulations using a Kinexus rheometer and Unchained Labs'​viscositystation.

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RAPID FORMULATION SCREENING OF BIOLOGICS WITH AUTOMATED VISCOMETRY

the system for viscosities from 1-51 cP. Before each
viscosity measurement the system automaticallywashed and dried the system. Using a disposable
Rainin positive displacement pipette tip, 100 μLof sample was injected at a precise flow rate into
the temperature-controlled (20 °C) capillary.
Viscosities were calculated by using the shear rate
and measuring the pressure response for eachsolution. Each measurement required approximately
6 minutes, including washing and drying.

are likely attributable to the physical and mecha­nistic
differences of the methods. Table 1 and Table 2 summarize the data from replicate measurements at highand low shear rates , respectively.
While both systems provide comparable results,
the viscosity station is faster and requires
significantly less manual intervention. Eachmeasurement required less than 6 minutes includ­ing measurement, washing and drying procedures.
The Kinexus rheometer required 30 minutes per
measurement including measurement, manual
washing and sample loading times. Table 3
compares the two methods for hands-on time,
run time and sample volume requirements. Theviscosity station not only measures viscosity fasterand uses less sample than the rheometer, butalso automates the entire process. Screening
40 samples takes 20 hours with the Kinexus

Results
Viscosity results for six drug product formulations withmAb concentrations ranging from 20–200 mg/mL aresum­marized in Figure 1. The same trends are observed
for both the Kinexus rheometer and the viscosity station
across the mAb concentrations tested. Differences in
the measured viscosities between the two instruments

High shear rate
mAb
(mg/mL)

Measurement(cP)

Average results

Averagemeasurement(cP)

RSD ofviscosity
(%)

0.9

1.9

Shearrate(s-1)

Flowrate(µL/s)

Averagemeasurement(cP)

RSD ofmeasurements
(%)

212

4

2

10

0.9
20

1.0
0.9
1.1

50

2.0
1.8

5436

2.6
70

2.7

10.0

2.6

23

4

9.8

7

106

41

4

2104

2.6
10.5
120

5.2
5.6
43.3

165

42.5

42.7

242.0
210.6
200

220.8

215.7

3N/A5232

9.6

5190

9.6

5365

9.9

1087

2.0

N/A

N/A

Table 1: Viscosity results of six mAb formulations from the viscosity station using various high shear rates formeasurements.

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RAPID FORMULATION SCREENING OF BIOLOGICS WITH AUTOMATED VISCOMETRY

Low shear ratemAb(mg/mL)

Measurement(cP)

Average results

Averagemeasurement(cP)

RSD ofviscosity
(%)

1.0

1

Shearrate (s-1)

Flowrate(µL/s)

Averagemeasurement(cP)

RSD ofmeasurements
(%)

122

10

1.0
20

1.0
1.0

2718

1.6
50

1.6

5.0

1.632.422174

4.0

34

10.3

51631

3.0

106

40.0

41359

2.5

414

203.4

N/A

652

1.2

N/A

N/A

210

4

1.7
2.4
70

2.4
2.5
10.8

120

10.2
9.8
41.4

165

38.6
40.1
203.4

200

N/A

Table 2: Viscosity results of six mAb formulations from the viscosity station using various low shear rates.

Kinexus

Unchained Labs

Required
hands-on time

Automated
analysis time

Required
hands-on time

Automated
analysis time

Setup time

5 min

N/A

5 min

N/A

Time persample

N/A

25 minN/A

5.6 min

Number ofsamplesTotal time40
3.3 hr40
16.7 hr

5 min

3.7 hrTable 3: Summarized measurement requirements for 40 samples using a Kinexus rheometer and Unchained Labs' viscosity station. Note that the Kinexus system requires scientists to return to the instrument
after every measurement, whereas the Unchained Labs' system operates in a fully unattended manner.

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RAPID FORMULATION SCREENING OF BIOLOGICS WITH AUTOMATED VISCOMETRY

References

rheometer, while the same analysis is complete inless than 4 hours with the viscosity station. Whenmea­suring 40 samples, the viscosity station is fivetimes faster and has a 40-fold decrease in handson time compared to the Kinexus rheometer.

1 Lorenz T, et al.
Developability
Assessment ofBiologics by Integrated Biologics
Profiling. American Pharmaceutical Review.
August 29, 2014.

Conclusion
The viscosity station on the freeslate jr. delivers
comparable results to the Malvern Kinexus
rheometer but is five times faster, with significantly
less hands-on time. With this system, a single
scientist can screen 200 formulations in a day with
only 25 minutes of hands-on time. Automating
manual assays such as viscosity measurement,
greatly improve lab productiv­ity. Combining
automated viscosity with automated pH, visualparticle analysis and turbidity on the freeslate
jr. or a freeslate platform can really accelerate
formulation development.

The viscosity stationon the freeslate jr.
is five times fasterand has a 40-folddecrease in handson time comparedto the Kinexus
rheometer.

2 Yang X, et al. Developability studies before initiation of processdevelopment. mAbs. 2013; 5(5):787–794.

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