Determining Replicates and Number of Dosage Units for Composite Sample Preparation in Drug Product Assay Nonclinical Biostatistics Conference 14 October 2015

Objective Develop strategy for determining number of dosage form units and replicates to use in preparing a sample for potency analysis Able to implement early in method development when data is scarce Based on current, defined compendia criteria Includes all solid oral dosage forms Recommendations appropriate per stage of development 2 DP Assay – Sample Composite Strategy

Outline Define a Drug Product Composite Sample Replicate Strategy for Potency Assays –What data is available? –What estimates required? –How deal with confounding? How Criterion Defined to Measure Adequacy 3

Example: Experimental Model – Drug Product Potency Assay A potency assay consist of a number of dosage units prepared into a sample of which there may be a number of replicate (r) sample preparations composited to form the reportable assay value. The below schematic illustrates such an experimental run. 4 Approach Where, S = sample preparation du = dosage unit Drug Product Assay Variability The Criterion we hold ourselves to for SE potency may be more restrictive if other components are significant contributors. method/sample preparation variability dosage unit variability

Approach used to Develop the Drug Product Sample Composite Strategy How? 5

Experimental Model 1 – Uniformity of Dosage Units To compute the uniformity of dosage (UDU), individual dosage units are prepared each into an individual sample preparation. The below schematic illustrates such an experimental run. 66 Approach – Total Variability Ests from UDU Where, S = sample preparation du = dosage unit Variance attributed to method/sample preparation Variance attributed to dosage unit

Approach – UDU and Assay Same Method 7 Content Uniformity:  CU 2 =  ε 2 +  η 2 (1) Potency Assay Repeatability:  POTENCY 2 = (  ε 2 +  η 2 /k)/r (with k dosage units per r sample composites)(2) Same Analytical Method used for UDU and Potency (and data for both): Taking (1) – r×(2) gives: (  CU 2 - r  POTENCY 2 ) = (  ε 2 +  η 2 ) – (  ε 2 +  η 2 /k) k(  CU 2 - r  POTENCY 2 ) = k  p 2 -  η 2 k(  CU 2 - r  POTENCY 2 ) = (k-1)  η 2 k(  CU 2 - r  POTENCY 2 )/(k-1) =  η 2 (3) Taking r×k×(2) – (1) gives: (kr  POTENCY 2 -  CU 2 ) = (k  ε 2 +  η 2 ) – (  ε 2 +  η 2 ) (kr  POTENCY 2 -  CU 2 ) = (k-1)  ε 2 (kr  POTENCY 2 -  CU 2 )/(k-1) =  ε 2 (4)

Approach – UDU and Assay Same Method 8 Content Uniformity:  CU 2 =  ε 2 +  η 2 (1) Potency Assay Repeatability:  POTENCY 2 = (  ε 2 +  η 2 /k)/r (with k dosage units per r sample composites)(2) Required Data: Content Uniformity per Lot Replicate Potency per Lot

Approach – UDU and Assay Different Method 9 Content Uniformity:  CU 2 =  μ 2 +  η 2 (1) Potency Assay Repeatability:  POTENCY 2 = (  ε 2 +  η 2 /k)/r (with k dosage units per r sample composites)(2) Different Analytical Method used for UDU and Potency: Requires an independent measure of each method variability Content Uniformity Data Potency Data

Experimental Model – Using Accuracy Experiment to Estimate Method/Sample preparation variability To Evaluate the Accuracy of an analytical potency method, spikes of known analyte amount are prepared each into an individual preparation. The below schematic illustrates such an experimental run. Preparation may be a pure placebo or a mix of product excipients to more closely mimic a typical product sample preparation. 10 Approach – UDU and Assay Different Method Where, C = Concentration preparation Sp = spiked amount Variance attributed to concentration preparation Variance attributed to spiked amount

Experimental Model – Using Accuracy Experiment to Estimate Method/Sample preparation variability 11 Approach – UDU and Assay Different Approximately equivalent to ? ~0

Approach – SOP Flow Chart

Prototype Tool 13

Approach used to Develop the Workflow How define the Maximum Criterion? 14

Approach used to Develop the Standard Error (SE) Criteria

16 Determine SE criterion TGO-78 criteria for n=20 –Most conservative regulatory recommendation: n=20 dosage units for potency assay 5.75 Maximum SE potency using n=20

This strategy provides guidance on number of units for assay composite and replicates Provides early stage of development assessment Requires limited data – Unit Dosage Uniformity and Assay Accuracy Estimate General Solution allows for different UDU and Potency Assay Methods Using surrogate method variability to estimate components of variance 17 Summary

DP Sample Composite LDT Members Marc Barber David Giamalva Michele Guo Carlos Lee Beverly Nickerson Garry Scrivens Loren Wrisley 18 Acknowledgements

19 & Questions