study design for bioavailability and bioequivalence

m.pharm pharmaceutics

1. BABASAHEB BHIMRAO AMBEDKAR UNIVERSITY PRESENTATION ON STUDY DESIGN AND STATISCAL CONCEPTS IN ESTIMATION OF BIOAVAILABILITY AND BIOEQUIVALENCE Presented By: Priya Singh Presented To: Dr. Sonali Singh

2. Bioavailability Bioavailability  is the fraction of an administered  dose  of unchanged drug that reaches the  systemic circulation . when a medication is administered  intravenously , its bioavailability is 100%.  when a medication is administered via other  routes  (such as orally), its bioavailability generally decreases (due to incomplete absorption and  first-pass metabolism ).

3. Types of Bioavailability There are two types…. Absolute bioavailability -  It is the fraction of the drug absorbed through non-intravenous administration compared with the corresponding intravenous administration of the same drug.

4. Relative Bioavailability - Relative bioavailability measures the bioavailability (estimated as the  AUC ) of a formulation (A) of a certain drug when compared with another formulation (B) of the same drug.

5. Bioequivalence Bioequivalence  is a term in  pharmacokinetics  used to assess the expected  in vivo  biological equivalence of two proprietary preparations of a drug. In order to determine that two medicines are bioequivalent there must be no more than a 20% difference between the AUC and Cmax.

6. Assessment of Bioavailability In vivo bioequivalence studies are conducted in the usual manner as discussed for bioavailability studies, i.e. …… 1. Pharmacokinetic Methods Plasma level-time study Urinary Excretion studies 2. Pharmacodynamic Methods Acute pharmacological response Therapeutic response

7. Pharmacokinetic Methods The parameter that are useful in determining the bioavailability of a drug from a drug product based on indirect methods… Plasma data Time of peak plasma conc.( t max) Peak plasma conc.(Cmax) Area under the curve (AUC) Urine data Rate of drug excretion in the urine (dXu /dt) Cumulative amount of drug excreted in urine (Xu) Time for maximum urinary excretion (tu)

8. Pharmacodynamics Methods In order to estimate the bioavailability of a drug product accurately by this method, the following criteria should be met…. An established dose- related response curve An easily measurable pharmacological response such as heart rate, ECG, blood pressure, pupil diameter etc.

9. Bioavailability Study Protocol Study objective Study design Experimental design Wash out period Drug products (test and std) Route of drug administration Dosage regimen Frequency and duration of sampling Randomization of drug administration Single versus multiple dose study design

10. Subjects Healthy versus patients Subject selection Medical history Physical examination Laboratory test iii. Study conditions Analysis of biological fluids C . Methods of assessment of bioavailability D. Analysis and presentation of data

11. PART 1 STUDY DESIGN FOR THE ASSESSMENT OF BIOAVAILABILITY AND BIOEQUIVALENCE

12. Study Design A good experimental design enhances the power of study. It depends upon the question to be answered, nature of reference drug/dosage form and risk benefit ratio. The study should be of cross over design and suitably randomized.

13. Subject Selection Healthy adult volunteers Age: 18-45 years Age/ sex representation corresponding to therapeutic and safety profile. Women: pregnancy test prior to 1 st and last dose of study Teratogenic Drugs: male volunteers

14. Study Conditions The selected subjects should be maintained on a uniform diet and none of them should taken any drug at least one week prior to the study. Fasting period before the administration. Standard diet to given after fasting, fluid intake and volume to be allowed.

15. Wash-out Period The time interval between two treatments is called “wash-out period”. It is require for the elimination of the administered dose of a drug so as to avoid carryover effect. Washout period is a function of the half-life and the dose of the drug administered, the number of washout period in a study depends on type of cross-over design used and the number of formulations to be evaluated .

16. Study Design There are various study designs…. Two Period cross-over design Latin Square Design Balance incomplete Block Design Parallel Group Design Replicate Cross-over study design

17. Two Period Cross-over Design For two formulations Even no. of subjects Randomly divided into 2 equal groups. First period, each member of one group receive a single dose of the test formulation, each member of the other group receive the standard formulation.

18. Subjects Period 1 Period 2 1-8 T S 9-16 S T

19. Latin Square Design For more than two Formulations. A group of volunteers will receive formulation in sequence.. Volunteer No. Period 1 Period 2 Period 3 1 A B C 2 B C A 3 C A B

20. Balance Incomplete Block Design (BIBD) More than 3 formulations, Latin square design will not be ethically advisable Because each volunteer mat require drawing of too many blood samples. If each volunteer expected to receive at least two formulation, then such a study can be carried out using BIBD.

21. Volunteer No. Period 1 Period 2 1 A B 2 A C 3 A D 4 B C 5 B D 6 C D 7 B A 8 C A 9 D A 10 C B 11 D B 12 D C

22. Parallel- Group Design Even no. of subjects in two groups. Each subject receive a different formulation. No washout necessary For drugs with long half life. This is also called as non- crossover study.

23. Treatment A Treatment B 1 2 3 4 5 6 7 8 9 10 11 12

24. Replicate Cross-over Study Design For highly variable drugs Allows comparisons of within- subject variance Reduce the number of subjects needed Four period, two sequence, two formulation design( recommended) Three period, two sequence ( partially replicated )

25. Period 1 2 3 4 Group A T R T R Group B R T R T Period 1 2 3 Group A T R T Group B R T R

26. PART 2 STATISTICAL CONCEPTS IN ESTIMATION OF BIOAVAILABILITY AND BIOEQUIVALENCE

27. Statistical Concepts In our study statistical analysis will be performed on PK data of subjects by using SAS statistical software . If they cannot be estimated, the subject will be excluded from the pertaining pharmacokinetic analysis. If necessary an unequal no. of subjects per sequence will be used

28. Analysis of Variance The various pharmacokinetic parameters (AUC (AUC 0-t and AUC 0-∞), Cmax) derived from the plasma concentration-time curve are subjected to ANOVA in which the variance is partitioned into components due to subjects, periods and treatments. The classical null hypothesis test is the hypothesis of equal means: μT=μR (i.e. products are bioequivalent), where - μT and μR represent the expected mean bioavailabilities of the test and reference formulations, respectively. The alternate hypothesis therefore is H: μT ≠ μR (i.e. products are bioinequivalent)

29. F - Test An F test will be performed to determine the statistical significance of the effects involved in the model at a significance level of 5% (alpha=0.05).

30. Ratio Analysis Ratio of least squares means for test and reference listed drugs (RLD) formulations will be computed and reported for Log-transformed pharmacokinetic parameters C max, AUC (0-t) and AUC (0-∞).