Kailas Thakker, PhDPresident Tergus Pharma, LLC.

Value of a Performance Test Efficacy of a drug product is measured by the

performance of the product during clinical trials which are:

Expensive

Time consuming

Unsuitable as routine tests

A performance test for a dosage form may serve as a surrogate test used to assure product quality.

1

2

3

Attributes of a Performance TestProvides a scientific rationale for

formulation selection

Ensures consistency in quality and manufacturing of a dosage form

Provides a uniform standard for comparing dosage forms across industry

Provides a measurable index to anticipate performance of the dosage form in the clinic

Dissolution and/or Drug

Release

Identify Critical Manufacturing

Variables

Formulation Development

Quality Control

Product Performance Assessment

Post Approval Changes

Gauge in-vivoPerformance

Why a Performance Test?

Regulatory Perspective on Performance Testing

Dosage Form Test

Parenteral Dosage forms Not Required

Immediate Solid Oral Dosage forms

Dissolution

Extended Release Oral Dosage forms

Dissolution/labeling

Transdermal Dosage forms Dissolution, In Vitro Release Testing(IVRT)

Inhalation Dosage forms None developed yet

Topical Dosage forms In Vitro Release Testing(IVRT)

Topical Dosage Forms Creams

Ointments

Gels

Emulsions

Topical Solutions

Topical Suspensions

Foams

Suppositories

Topical Aerosols

Transdermal Systems

Product Quality TestsUniversal Tests Specific Tests

Description Uniformity of Dosage Units

Identity Water Content

Assay Microbial Limits

Impurities Antimicrobial Preservative

Content

Antioxidant Content

Sterility

pH

Particle Size

USP Chapter <1724> To be official in fall 2013

Describes the apparatus to be used for performance test for topical and transdermal dosage forms

For topical dosage forms: Vertical diffusion cells –three models

immersion cells

USP apparatus 4

For transdermal dosage forms: USP apparatus 5 Paddle over disk

USP apparatus 7

Performance tests for topical dosage forms: USP

Chapter <1724> describes

Different apparatus and modifications of each that can be used to develop performance test (IVRT) for topical dosage forms

Guidance in developing IVRT with respect to the selection of key parameters

Recommendations on validation attributes and test parameters hat should be validated

In Vitro Release Test (IVRT) Traditionally, a variety of physical and

chemical tests such as

solubility

particle size

viscosity

form of API (crystalline or amorphous)

have been used to assure product performance for a semisolid dosage form

More recently, In Vitro Release Test (IVRT) has

provided a means of comprehensively and more directly assuring

performance of a dosage form.

In Vitro Release Test (IVRT): Apparatus

Vertical diffusion cells

Immersion cells

USP Apparatus 4

The principle is to determine the diffusion of active ingredient from the semisolid matrix

across a membrane

into an appropriate medium

representing the clinical use of semisolid dosage form as close as possible

Vertical Diffusion Cells General specifications are:

Cell body made of borosilicate glass. Other materials are acceptable as long as there is not interaction between the cell material and sample

Diameter of the orifice the donor chamber must be always smaller than or equal to the diameter of the receiving chamber

All cells should have same nominal value (± 10%) and the volume must be determined experimentally

Stirring rate should remain constant during the test

Thickness of the receiving chamber is generally 1.5 mm (±10% of the specified value)

Vertical Diffusion Cells In practice:

The cells are designed after well known Franz Diffusion Cells

Basic design includes two chambers(receiving and donor chambers) separated by a barrier

A jacketed receiving chamber with volume between 7 to 15 ml, stirred at constant speed

Donor chamber to hold the dosage form, can be occluded if required

Sampling arm to allow sampling just below the dosage form

Vertical Diffusion Cell (VDC)

Transdermal and Topical Release-Rate

Testing Rev. 7-11 ©2011 Hanson Research Corp. 14

Vertical Diffusion Cell

Crown Glass Model

Layout of IVRT Apparatus

Automated Apparatus

Application of IVRT Methods During Development Cycle

DEVELOPMENT PHASE

Selection of appropriate clinical candidate formulation and

characterization of the dosage form

CLINICAL PHASES

Monitoring and correlating the in- vivovs. in- vitro results—

further characterization of final formulation

POST –APPROVAL

Changes in manufacturing site,

composition, manufacturing process

Theory Fick’s first law of diffusion:

J= -D δc/δx where

J = rate of transfer per unit surface area(flux)

c = the concentration of the diffusing substance

x = distance the substance travels at right angles to the plane and

D = the diffusion coefficient in (length)2(time)-1

Theory Fick’s second law of diffusion:

δc/δt = D(δ2C/δx2 + δ2C/δy2 + δ2C/δz2 )

More simply,

δc/δt = D*δ2C/δx2

In case of release of active ingredient from a stationary matrix such as an ointment, (“moving boundary”case) the model can be simplified as follows:

Theory When the drug particles are uniformly distributed in the

matrix, and when their size is much smaller than the distance they have to travel, and when the sink conditions prevail in the receptor phase,

M ~ (2A-Cs) { Dvt/(1+{2(A-Cs)/Cs})}1/2

When A>>Cs,

M ~ (2ADvCst)1/2 and dM/dt ~ (ADvCs/2t)1/2

Theory For a case where the drug is dissolved in the matrix,

Higuchi derived the equation

M = h A{1 – 8/Π2 Σ *exp*-D(2m + 1)2 Π2]]/(2m+1)

Where h = the thickness of the ointment phase

For the first 30% of the release, the equation simplifies to:

M = 2A (D * t/Π)1/2

Calculation of Release RateThe cumulative amount (Q) of API released per surface area of membrane is:

n-1

Q = { CnV + Σ Ci S }/A i=1

Where:

Q = Cumulative amount of API released per surface area of membrane (mg/cm2)

Cn = Concentration of API (mg/mL) determined at nth sampling interval

V = Volume of individual Franz diffusion cell; determined by weighing out the receivingmedium required to fill the chamber and then dividing the weight by density toobtain the volume of the cell

n-1

ΣCi = Sum of concentrations of API (mg/mL) determined at sampling intervals 1 through n-1i=1

S = Volume of sampling aliquot, 0.2 mL

A = Surface area of sample well

The release rate is the slope of the line described by Q values verses the square root of time

Conditions under which the equation holds are:

Only the drug diffuses into the receptor phase while other components, excipients, do not diffuse or evaporate

The diffusion coefficient of the drug remains constant

The barrier membrane does not interact with the drug

Factors Affecting the Release of API from a Semisolid Dosage Form

1. Particle size of API

2. pH of API

3. Incorporation of API in semisolid matrix

4. Solubility of API in semisolid matrix

1. Viscosity

2. Spread ability

3. Overall pH

4. Moisture content of dosage form

1. Presence of emollients and penetration enhancers

2. Effect of excipients on release of API from matrix

3. Compatibility of excipients with API and with environmental agents such as moisture, gases, to affect the release of API

4. Manufacturing process

5. Manufacturing site

Considerations in Developing a Release Test Using Vertical Diffusion Cells

The Release Test Must be

Accurate in providing same release profile from day to day for the same lot of formulation

Discriminatory for different dosage strengths

Sensitive to differences in excipients

Rugged

Robust

Steps in Developing a Release Test

Assay Method –May need modifications

Selection of Membrane: Inert holding surface

Selection of Receiving Medium: Sink conditions must prevail, 30% rule

Introduction - Summary In principle, release tests are based on passive diffusion

of active ingredient from the product matrix into a receiving medium

There are many tests/apparatuses for different types of semisolid dosage forms

Among these, release testing using Vertical diffusion cells is widely used for many traditional and novel topical products

Case Study #1: Performance Test for a Topical Vaginal Gel – Method Development

API is

An anti-microbial agent

Needs to be formulated in a gel for vaginal use

Solubility profile shows pH dependence

Formulation is

Vaginal gel

Pharmacological data showed a dependence of moisture present in the environment to affect the release rate

Selection of Membrane: Filter Interference

Membrane % Recovery vs. unfiltered standard

Formulation1(0.02%)

Formulation 2(0.02%)

Formulation 3(0.05%)

Formulation 4(0.05%)

Cellulosic 83 82 90 87

Fluoropore 89 86 97 90

Nylon 92 85 99 89

Polycarbonate 96 90 104 95

Supor 89 85 96 89

Selection of Receiving Medium: Solubility of API in Receiving Medium

*Phosphate buffer pH 4.0

Solubility of API in 30:70 EtOH:phosphate buffer is too low for sink conditions especially for doses higher than 0.05%

Solubility of API in 40:60 EtOH:phosphate buffer is sufficient to allow for sink conditions 40:60 receiving medium was selected for next studies

Solvent Ratio(EtOH:Aqueous*)

Solubility(µg/mL)

Aqueous Sparingly Soluble

30:70 6.89

40:60 64.09

50:50 216.61

Preliminary Release Rate Test Conditions Preliminary IVRT conditions:

Heater/circulator set to 37 ± 0.05°C for vaginal application

Cells filled with receiving medium (ethanol:phosphate buffer pH 4.0, 40:60)

Membrane (polycarbonate) clamped onto bottom of each of 6 cells

~300mg vaginal gel applied to each cell

200µL aliquot removed at 0.5, 1, 2, 4, 6, and 24 hours and replaced with fresh medium

API concentration in receiving medium determined by reversed-phase HPLC

The conditions were further optimized during method development (noted in subsequent slides)

Preliminary Studies: Test Gel Variants

Form. No. API (%) Gel Type Gel Content Variations

A 0.01 Solution PG, polymers, pH 7

B 0.02 Suspension EtOH, polymers, pH 6

C 0.02 Suspension

Vitamin E, TPGS, PG, polymers, pH 6D 0.05 Suspension

E 0.02 Solution

F 0.01 Solution

G 0.02 SolutionCremophor, PG, polymers, pH 6

H 0.01 Solution

J 0.02 SolutionTween20, PG, polymers, pH 6

K 0.01 Solution

Variables to be Evaluated for Dependence on Release Rate:

Composition of Formulation

Dosage form Strength

Particle Size of API

Stress/viscosity

Air exposure

Sample weight

Consistency in release rate over time

Release Rate Dependence on Formulation Composition

API

(% w/w)Formulation

Release Rate

(mg/cm2/hr 0.5)

Standard

Deviation%RSD

0.012% vitamin E TPGS, 28% propylene glycol, modified

polymers, pH62.90 0.64 22

0.012% Tween 20,

28% propylene glycol, modified polymers, pH65.63 0.36 6.4

0.012% Cremophor,

28% propylene glycol, modified polymers, pH65.86 0.93 16

0.01 40% propylene glycol, modified polymers, pH7 6.14 1.2 19

0.0252% Cremophor,

28% propylene glycol, modified polymers, pH611.7 1.1 9.3

0.0252% vitamin E TPGS, 28% propylene glycol, modified

polymers, pH611.9 1.3 11

0.0252% Tween 20,

28% propylene glycol, modified polymers, pH613.9 2.0 15

0.025vitamin E TPGS,

5% propylene glycol, modified polymers, pH614.7 2.3 16

0.0254% ethanol,

modified polymers, pH615.4 2.0 13

Release Rate Dependence on Particle Size

Formula 2 Formula 1

Formulation Number

A-2 A-5 A-6 A-1 A-3 A-4

API Conc. 0.025% 0.05% 0.05% stressedb 0.10% 0.05% 0.05% 0.025% 0.05% .1% 0.05% .05%

% Dose 50 100 100 200 100 100 50 100 200 100 100

Milling Type Source

Milled at facility 1c

Milled at

facility 2d

Non-milled Milled at facility 1c

Milled at

facility 2d

Non-milled

Particle Size (d90)

<5 µm15.1 µm

144 µm <5 µm15.1 µm

144 µm

a The primary and secondary formulations are similar water-based gels that differ in solvent and preservative content. The primary formulations contained deionized water, methylparaben, propylparaben, HEC, polycarbophil, NaOH solution, propylene glycol, and vitamin E. Secondary formulations contained deionized water, sorbic acid, NaOH solution, dapivirine, HEC, Pluronic F127NF, and Klucel MF Pharm.

b Compound was stressed at 60 C for 4 weeksc Jet micronization at Facility 1d Jet micronization at Facility 2

Application of Release Rate Measurement During Stability Testing: 30 C 60% R.H.

Case Study #1: Conclusions Dose proportionality was demonstrated for two lead formulations

selected from a range of API concentrations of 0.025% to 0.1% (w/w)

Release profiles depended on formulation composition and on stress-induced viscosity changes

The IVRT method could distinguish between stressed and unstressed gels that differed in magnitude of viscosity from 8.26 kPa to 10.8 kPa, and showed a trend between milled and non-milled API

Release Rate was consistent over several months for the two lead formulations

Release Rate showed little variability during stability storage at 30°C/60% RH and 40°C/75% RH.

Case Study #2: Using Performance Test to Support Development of a Formulation for an Age Defying Cream

API is a light sensitive molecule, well studied

Hydrophobic with low aqueous solubility

Purpose: Needed formulation support to select appropriate formulation for clinical studies

Action: Determined sensitivity of the release profile to several physico-chemical parameters

IVRT Method Cellulose Acetate Membrane 0.45 µ

Receiving Medium: 35:65 Ethanol: pH 3.5 Phosphate Buffer

Sampling over 0.5, 1, 2, 4, 6 and 24 hours

32 ͦC

Formulation not occluded

Validation of an IVRT MethodAttributes that are Desired to be validated:

Intra-run Precision between 6 cells

Inter day precision –at least over 3 days

Discriminatory power:

Dose proportionality

Sensitivity to changes in

Excipient type

Amount of Excipient

Size of Batch

Method of manufacture

Validation of IVRT Method

Ruggedness : analyst, instrumentation

Robustness

Media composition

Membrane supplier, type

Dosage form application : method, volume

Cell design

Mass Balance

Back Diffusion of Alcohol into the Dosage Form

IVRT Method Ruggedness

Discrimination: Sensitivity to Changes: Process

Average Flux For Compound 1 Formulations (μg/cm2/hours1/2)

Formulation Drug Dissolved in Flux

1-A 100% pre-dissolved in organic solvent 0.189

1-B60% pre-dissolved in organic solvent, 40% dissolved directly into oil phase

0.110

2-A 100% dissolved in oil phase 0.603

2-B 100% pre-dissolved in organic solvent 1.406

Discrimination: Sensitivity to Changes: Scale-up

Average Flux For Compound 1 Formulations (μg/cm2/hours1/2)

Formulation Lot #Avg Flux

μg/cm2/hours1/2

Avg. Total Amt. Released After 6 hours std. dev.

1 A (3 kg) 0.347 1.200 0.071

1 B (100 kg) 0.406 1.412 0.028

2 A (3 kg) 0.054 0.145 0.021

2 B (100 kg) --- 0.020 0.013

3 C (3 kg) 0.290 0.855 0.140

3 C (100 kg) 0.258 0.799 0.085

Discrimination: Sensitivity to Change: Physical Parameters — Effect of Viscosity Builder

FormulationExcipient(%w/w)

Flux (μg/cm2/hours1/2)

Avg. Total Amt. Released after 6 hours (μg)

1 10 0.406 1.412

2 10 0.347 1.200

3 5 1.391 4.766

4 0 2.134 7.287

5 10 0.258 0.799

6 10 0.290 0.855

7 0 1.473 4.458

8 10 -- 0.020

9 10 0.054 0.145

10 10 0.084 0.256

11 0 0.078 0.231

Conclusions: Case Study #2The IVRT method is

Accurate and Precise

Rugged

Sensitive to differences in Excipients,

Dosage strength,

Viscosity of formulation

Process changes

Other Applications of Vertical Diffusion Cells

Rapidly disintegrating oral tablets

Ocular dosage forms – solutions, suspensions-release across ocular membrane — modified Franz cell to mimic clinical application

Film forming dosage forms, devices — useful characterization of the dosage form.

Transdermal dosage forms

Case Study #3: Characterization of a Polymer Film

The polymer film is a device used for curing toe nail fungus.

Our objective was to characterize the film for its integrity to permeation of small and large molecules.

Vertical diffusion cells were used where the permeation profiles of two marker compounds from a cream applied on the polymer film were evaluated for the integrity of the polymer film.

Study Design

Polymer film prepared on nylon membrane

Polymer applied on the membrane using the brush provided using smooth strokes in one direction

For multiple applications (layers), film allowed to air dry and the next layer applied at right angles to the first one, using the same smooth strokes

Integrity of the film tested for permeation of hydrophobic (hydrocortisone) and hydrophilic (lucifer yellow) markers.

Case Study #4: Using IVRT for a Sublingual Tablet

Sub-lingual tablets release their active ingredient in the mouth; the active then moves across the mucosal membrane of mouth/tongue.

The disintegration of a sub-lingual tablet takes place instantaneously as it is placed in an aqueous environment.

The two-step process can be simulated using an IVRT VDC.

The flux of the active across a relevant membrane was determined after dosing the sublingual tablet to a VDC.

Donor chamber

Receiving chamber

Vertical Diffusion Cell (VDC)

Study Design Biologically relevant membrane is human mucosal

membrane

Next best option would be pig tongue or Goat Mucosa

Both are hard to obtain and use

Cultured cell lines - artificially grown cells - were used instead

Trade name: EpiOral®

Use of Vertical Diffusion Cells for

Implementation of SUPAC-SS Guidelines

US FDA

SUPAC-SS Guidance Issued in May 1997

IVRT can be substituted for a clinical trial in certain cases

Excipients:

Level 2 change: changes that are likely to have a significant impact on formulation quality and performance. Examples are:

changes in >5% but <10% of an approved excipient

changes in supplier or technical grade of a structure forming excipient

changes in particle size of API when it is suspension

Level 3 change: changes that are likely to have a significant impact on formulation quality and performance. Examples are:

changes in excipient beyond the ranges in level 2

changes in crystalline form of API—IVRT not required but highly encouraged

Manufacturing and ProcessesManufacturing:

Level 2 change

change in equipment to a different design or different operating principles—IVRT required

Process:

Level 2 change

process change such as rate of mixing

mixing times, rate of cooling

operating speeds

holding times outside approved application ranges (IVRT required)

Manufacturing and ProcessesBatch size:

Level 2 change

Changes in batch size beyond a factor of ten times the pivotal/clinical batch (IVRT required)

Manufacturing site

Level 3 change

Different campus (IVRT required)

Implementation of SUPAC-SS Requirements IVRT method should be established during development phase

Data is collected for one or more likely candidates for clinical formulation

IVRT method is validated for at least one final formulation

Upon post approval change(s), the new batch manufactured after change is compared with reference batch (manufactured before change)

First Level of Comparison 6-cell run each with reference and test batch carried

out simultaneously

For each run, it is suggested that the experiments be run as follows:

Slopes are calculated for each cell.

Ratios of slopes are calculated as shown in example and ranked.

Criteria: 8th and 29th ranked slope ratios should fall between 75% and 133.33%.

T R T

R T R

Example of SUPAC-SS Statistical Comparison Between Two Formulations

T/R Ratios 25.03 25.26 23.14 29.98 27.10 22.79

21.29 117.57 118.67 108.68 140.85 127.32 107.06

20.13 124.33 125.50 114.94 148.95 134.65 113.22

20.09 124.60 125.77 115.18 149.27 134.94 113.47

19.50 128.34 129.54 118.64 153.75 138.99 116.87

21.00 119.18 120.30 110.17 142.78 129.07 108.53

21.74 115.12 116.19 106.41 137.91 124.67 104.83

Rank order

20 22 11 38 30 9

25 28 15 40 34 13

26 29 17 41 35 14

31 33 21 42 37 19

23 24 12 39 32 10

16 18 8 36 27 7

Second Level of Testing Failure at first level triggers the second level

of comparison

4 additional runs of 6-cell each are carried out and slopes are computed.

A total of 18 slopes for each batch is obtained and same T/R ratios are computed and ranked.

Criteria: 115th and 225th ranked ratios should fall within 75 to 133.33%

Summary IVRT is a useful test during product development,

allowing appropriate selection of a clinical candidate and can serve as a cost effective means to monitor the consistency in manufacturing of semi-solid dosage forms during clinical trials.

Vertical diffusion cells can be used to develop performance tests for a variety of dosage forms including semi solids, film formers, occular, nasal etc.

THANK YOUQuestions???

Kailas Thakker

Kailas.Thakker@terguspharma.com

919-549-9700 ex 100

www.terguspharma.com