BIOEQUIVALENCE TESTING Roger K VERBEECK Ph D SCHOOL

BIOEQUIVALENCE TESTING Roger K. VERBEECK, Ph. D. SCHOOL OF PHARMACY UCL – Brussels BELGIUM roger. verbeeck@uclouvain. be

OUTLINE l l l Concept of bioavailability Historical cases of bio-inequivalence Bioequivalence testing : EMA and FDA guidelines Study designs Bioequivalence criteria Special issues

A representative sample of the slides that will be presented and discussed during the course is displayed hereafter.

PHARMACOKINETICS Temporal characteristics of drug effect and relationship to therapeutic window (e. g. , single dose, oral administration).

BIOAVAILABILITY l The extent and the rate to which a drug substance or its therapeutic moiety is delivered from a pharmaceutical form into the general circulation absolute bioavailability relative bioavailability

ABSOLUTE BIOAVAILABILITY

RELATIVE BIOAVAILABILITY tablet A □ tablet B

BIOAVAILABILITY AUC 1 AUC 2 AUC 3 AUC 1=AUC 2=AUC 3 Cmax Tmax Changes in extent and/or rate of absorption influence the drug plasma concentration-time profile and may therefore affect therapeutic efficacy

BIOAVAILABILITY formulation and physicochemical factors influencing drug absorption and bioavailability

BIOAVAILABILITY The practical importance of BA/BE testing has been demonstrated by a number of clinical reports in the 60’s and the 70’s documenting medical problems due to bio-inequivalence l To allow prediction of therapeutic effect the performance of the pharmaceutical dosage form containing the active substance should be known and reproducible l

BIOAVAILABILITY l Outbreak of phenytoin intoxication around 1970 in Queensland, Australia l Calcium sulphate dihydrate in the phenytoin capsules had been replaced by lactose Tyrer et al. : Outbreak of anticonvulsant intoxication in an Australian city. Brit. Med. J. 4: 271 -273, 1970.

BIOAVAILABILITY Lindenbaum et al. : Variation in the biologic availability of digoxin from four preparations. New Engl. J. Med. 1344 -1347, 1971.

BIOEQUIVALENCE l “Two medicinal products containing the same active substance are considered bioequivalent if they are pharmaceutically equivalent or pharmaceutical alternatives and their bioavailabilities (rate and extent of absorption) after administration in the same molar dose lie within acceptable predefined limits. These limits are set to ensure comparable in vivo performance, i. e. similarity in terms of safety and efficacy. ” GUIDELINE ON THE INVESTIGATION OF BIOEQUIVALENCE, EMA (LONDON), 2010.

BIOEQUIVALENCE TESTING BE tests are not only required for the registration of generic drugs but are also carried out during the development of new drugs: e. g. during scale-up and for post-approval changes (SUPAC).

IMMEDIATE RELEASE DOSAGE FORMS http: //www. ema. europa. eu/docs/en_GB/document_library/Scientific_guideline/2010/01/WC 500070039. pdf

FDA Guidance for Industry http: //www. fda. gov/downloads/Drugs/Guidance. Compliance. Regulatory. Informa tion/Guidances/ucm 072872. pdf

EMA Guideline on the Investigation of Bioequivalence, 2010 l STUDY DESIGN - standard design: randomized, two-period, two-sequence, single dose cross-over design - alternative designs: parallel design (substances with very long half-lives) and replicate designs (in case of highly variable drugs or drug products)

2 x 2 CROSS-OVER DESIGN subjects R A N D O M I Z A T I O N period 1 sequence 1 R sequence 2 T period 2 W A S H O U T T R

TWO-GROUP PARALLEL DESIGN subjects R A N D O M I Z A T I O N group 1 TEST group 2 REFERENCE

REPLICATE DESIGN 4 -period, 2 -sequence, 2 -formulation design period subjects R A N D O M I Z A T I O N I II IV sequence 1 T R sequence 2 R T wash-out

EMA Guideline on the Investigation of Bioequivalence, 2010 l STUDY SUBJECTS - the number should be based on an appropriate sample size calculation ( 12), - healthy volunteers to reduce variability, - strict inclusion/exclusion criteria, - subjects could belong to either sex, - preferably non-smokers and without a history of alcohol or drug abuse, - patients, if the investigative active substance is known to have serious adverse effects considered unacceptable for healthy volunteers

EMA Guideline on the Investigation of Bioequivalence, 2010 l o SAMPLING TIMES “The sampling schedule should include frequent sampling around the predicted tmax to provide a reliable estimate of peak exposure. In particular, the sampling schedule should be planned to avoid Cmax being the first point of the concentration-time curve. ” Sampling times: 0, 0. 5, 1, 2, 4, 6, 8 and 12 hours.

EMA Guideline on the Investigation of Bioequivalence, 2010 l SAMPLING TIMES “The sampling schedule should also cover the plasma concentration time curve long enough to provide a reliable estimate of the extent of exposure which is achieved if AUC 0 -t covers at least 80% of AUC 0 -. At least 3 to 4 samples are during the terminal loglinear phase in order to reliably estimate the terminal rate constant, which is needed for a reliable estimate of AUC 0 -. ”

EMA Guideline on the Investigation of Bioequivalence, 2010 l PRIMARY PARAMETERS: - AUC 0 -t or AUC 0 -72 h: extent of absorption - Cmax: extent and rate of absorption - Tmax: rate of absorption

RATE OF ABSORPTION partial AUC l For drug products where rapid absorption is of importance, partial AUCs can be used as a measure of early exposure (FDA Guidance for Industry, 2003). l The partial area can in most cases be truncated at the population median of Tmax values for the reference formulation: AUCtmax

EMA Guideline on the Investigation of Bioequivalence, 2010 l BIOANALYTICAL METHODOLOGY The bioanalytical part of BE trials should be performed in accordance with the principles of Good Laboratory Practice (GLP). EMA draft Guideline on Validation of Bioanalytical Methods, London, November 2009.

EMA Guideline on the Investigation of Bioequivalence, 2010 l BIOEQUIVALENCE CRITERIA: are based on the calculation of a 90% confidence interval according to the two onesided tests procedure of Schuirmann D. J. Schuirmann: A comparison of the two one-sided tests procedure and the power approach for assessing the equivalence of average bioavailability. J. Pharmacokinet. Biopharm. 15: 657 -680, 1987.

EMA Guideline on the Investigation of Bioequivalence, 2010 l The pharmacokinetic parameters under consideration (e. g. AUC 0 -t, Cmaxin case of a single dose BE study) should be analysed using ANOVA. l The data should be transformed prior to analysis using a logarithmic transformation. l The terms to be used in the ANOVA model are usually sequence, subject within sequence, period and formulation. l A statistical evaluation of tmax is not required. However, if rapid release is claimed to be clinically relevant and of importance for onset of action or is related to adverse events, there should be no apparent difference in median tmax and its variability between test and reference product.

90% CONFIDENCE INTERVAL la 90% confidence interval has to be calculated around the ratio of geometric means obtained for AUC (and Cmax) following administration of test and reference preparation l this ratio of geometric means is called the point estimate

EMA Guideline on the Investigation of Bioequivalence, 2010 l For Cmax and AUC 0 -t the 90% confidence interval for the ratio of the test and reference products should be contained within the acceptance interval of 80. 00125. 00%. l In specific cases of products with a narrow therapeutic range, the acceptance interval may need to be tightened. Moreover, for highly variable drug products the acceptance interval for Cmax may in certain cases be widened (by using the reference scaled average bioequivalence approach).

90% CONFIDENCE INTERVAL 90% CI 1. 04 (0. 91 – 1. 20) point estimate 0. 80 1. 04 1. 25

NARROW THERAPEUTIC INDEX DRUGS EMA BE guideline - 2010 In specific cases of products with a narrow therapeutic index (NTI), the acceptance interval for AUC should be tightened to 90. 00 -111. 11%. l Where Cmax is of particular importance for safety, efficacy or drug level monitoring the 90. 00 -111. 11% acceptance interval should also be applied for this parameter. l It is not possible to define a set of criteria to categorise drugs as NTI drugs and it must be decided case by case if an active substance is and NTI drug based on clinical considerations. l

BIOPHARMACEUTICS CLASSIFICATION SYSTEM (BCS) permeability dissolution solubility l solubility, dissolution and permeability are the 3 major factors controlling the oral absorption of drug substances from IR oral medicinal products

BIOPHARMACEUTICS CLASSIFICATION SYSTEM (BCS) Class II High solubility High permeability Low solubility High permeability Class III Class IV High solubility Low permeability Low solubility Low permeability Amidon et al. : A theoretical basis for a biopharmaceutic drug classification: the correlation of in vitro drug product dissolution and in vivo bioavailability. Pharm. Res. 12: 413 -420, 1995.

BIOPHARMACEUTICS CLASSIFICATION SYSTEM (BCS) l the BCS was developed for regulatory applications: to provide a basis for replacing, in certain cases, in vivo BE studies by equally or more accurate in vitro tests l biowaiver: an acceptance for replacing an in vivo BE study with in vitro dissolution testing