bioavailability studies(BA) -presentation

bioavailability(BA) studies

1. Bioavailability studies Presenter : Dr. Shilpi Rani Biswas (JR3) Moderator: Dr. Shakeel Ahmad ( SR) Peer support : Dr. Alisha Raj (JR3) Junior Resident 3 rd year Department of Pharmacology & Therapeutics King George’s Medical University, Lucknow, U.P., India E-mail: [email protected]

2. Contents Introduction Purpose of bioavailability & bioequivalence study Types of bioavailability Assessment of bioavailability & bioequivalence study Process to conduct bioavailability & bioequivalence study Summary References

3. Specific learning objectives At the end of this session the audience will be able to Understand need for bioavailability studies Describe study design of bioavailability assessment Identify parameters used in bioavailability studies Explain acceptance criteria for bioavailability studies

4. ANDA : Abbreviated New Drug Application BA : Bioavailability BE : Bioequivalence CDSCO : Central Drugs Standard Control DCGI :Drugs Controller General India EC : Ethical committee NDA : New Drug Application Abbreviations

5. NDCT : New Drug and Clinical Trial Rule US-FDA : United States  Food and Drug Administration AD : Assistant Drug Inspector DI : Drug inspector ADC : Assistant Drug Controller DDC : Deputy Drug Controller JDC : Joint Drug Controller  

6. Introduction Bioavailability(BA) & bioequivalence(BE) studies play important role in new drug development & for marketing approval of generic equivalence Drug Controller General of India(DCGI), has provided regulatory guidelines to conduct BA and BE studies NDA(New Drug application) & ANDA(Abbreviated New Drug Application)

7. Definition Bioavailability study means a study to assess the rate and extent to which the drug is absorbed from a pharmaceutical formulation and becomes available in the systemic circulation or availability of the drug at the site of action (Source : NDCT Rule 2019)

8. Bioequivalence study means a study to establish the absence of a statistically significant difference in the rate and extent of absorption of an active ingredient from a pharmaceutical formulation in comparison to the reference formulation having the same active ingredient when administered in the same molar dose under similar conditions (Source : NDCT Rule 2019)

9. The reference product It is expected that reference product for BA and BE studies should normally be the innovators product , to which all generic versions should be shown bioequivalent If in case an innovator product is not available the applicant may use an Indian product approved by CDSCO as a reference product

10. The Orange Book US-FDA approved Lists Approved drugs Discontinued drugs Provides patent and exclusivity information Published annually with monthly cumulative contents

11. Purpose of BA and BE study To ensure the release of the active drug from the formulation to the site of absorption, distribution, metabolism & excretion Ensure the excipient used are appropriate and adequate in quantity For the approval of generics for submission of ANDA

12. New drug development: to establish equivalence between formulations used in Early and late clinical trials Clinical trials and stability studies Clinical trials and products to be marketed to observe if there is any effect due to changes in manufacturing process occurring during drug development stages

13. Types of Bioavailability Absolute Bioavailability ( F ) Relative bioavailability (F r ) Compares the bioavailability of active drug following non-intravenous and intravenous administration Measure of the fraction of the given drug that is absorbed in the systemic circulation from a particular dose compared to a clinically proven standard dose of the same drug Relative bioavailability (F r ) Compares the bioavailability of active drug following non-intravenous and intravenous administration Measure of the fraction of the given drug that is absorbed in the systemic circulation from a particular dose compared to a clinically proven standard dose of the same drug

14. Plasma level studies – single dose study C max (peak plasma concentration): maximum concentration of drug obtained T max (time of peak plasma concentration): time required to achieve peak concentration of drug AUC 0-t : area under the plasma concentration time curve from time zero to time t (where t is the last time point with a measurable concentration)

15. AUC = AUC0-2+ AUC2-4+ AUC4-6+ AUC6-8+ AUC8-10+ AUC10-12+ AUC last- infinity

16. AUC 0-∞ extrapolates the area to infinite time Comprises AUC 0-last plus extrapolated area AUC t-∞ calculated by C pt = plasma concentration at last quantifiable time point K el = terminal elimination rate constant AUC 0-∞ = C pt / K el

17. Plasma level studies- multiple dose study Cp max – max plasma concentration at steady state Cp min - min plasma concentration at steady state t peak -time of peak plasma concentration

18. Drugs having very long elimination half-lives Modified release forms demanding evaluation of fluctuations in plasma concentration over a dosage interval Drugs with non-linear (dose or time dependent) pharmacokinetics; Drugs with large intra-individual variability Drugs having tendency to accumulate in body

19. Urinary excretion studies Indirect method for estimating bioavailability The drug must be excreted in significant quantities(at least 20%) as unchanged drug in the urine Timely urine samples must be collected and the total amount of urinary drug excretion must be obtained Method is useful when there is lack of sufficiently sensitive analytical technique to measure drug concentration

20. ( dXu /dt) max = max urinary excretion rate ( tu ) max = time for maximum urinary rate Xu ∞ = cumulative amount of drug excreted in urine

21. Acute pharmacological response Measurement of pharmacological responses Change in ECG or EEG readings, pupil diameter etc Pharmacological effect-time curve & dose response curve Disadvantages Variable pharmacological response Accurate correlation between measured response and drug available is difficult

22. Therapeutic response method Observing clinical response to drug formulation given to patient suffering from disease for which it is intended to be used Response observed is often too improper

23. Permission to conduct BA and BE studies Application in Form-44 duly signed, by the competent authority with name and designation Treasury Challan of Rs. 25000/- Study protocol Informed consent form Case report form Undertaking by investigator

24. Sponsor’s authorisation letter Pre-clinical single dose data and repeated dose toxicity data Injectable preparation the sub-acute toxicity should be submitted on the product of the sponsor generated in two species for adequate duration Cytotoxic agent, hormonal preparations etc. Proper justification for conducting studies on healthy volunteers/patients or male/ female should be submitted

25. ADI (Assistant Drug Inspector) DI (Drug inspector) ADC (Assistant Drug Controller) DCGI (Drug Controller General of India) DDC (Deputy Drug Controller) JDC (Joint Drug Controller) Source : CDSCO

26. Study design Cross-over design Parallel design Replicate cross-over design Latin square designs Balanced incomplete block design

27. 2 x 2 Cross-over design RANDOMIZATION sequence 1 sequence 2 period 1 period 2 WASHOUT R T T R subjects

28. Parallel Design For drug, and its metabolites have long elimination half-life Two formulations are administered to two groups of volunteers Major disadvantage –inter subject variation is not being corrected Carryover effects or dropouts were less compared to crossover studies

29. RANDOMIZATION subjects sequence 1 sequence 2 R T T R period T R R T I II III IV wash-out Replicate design (4-period, 2-sequence, 2-formulation design)

30. Latin Square Design More than two formulations A group of volunteers will receive formulations in the sequence shown

31. Balanced Incomplete Block Design (BIBD) More than 3 formulations, Latin square design will not be ethically advisable Because each volunteer may 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

32. Study subjects a) Healthy adult volunteers b) Age (18- 55years) d) If the drug is intended for elderly age group: ≥ 60 years e) The drug with high risk of toxicity or side effects – patients with the concerned disease, provided that the disease is in a stable state

33. e) Either gender can participate – Safety criteria Studies on teratogenic drugs should be conducted only on males Pregnant and lactating females are excluded Women on oral contraceptives are excluded f) The selected participants should be standardized as much as possible to minimize intra and inter  individual variation

34. Study type Fasting study Immediate release and modified release orally administered dosage forms Fasting: overnight fast of minimum 10 hours before drug administration followed by 4 hours fasting after drug administration No other medication given to the subjects for at least 1 week before study

35. Fed-state/ Food intervention/ Food effect study For all modified- release dosage forms For immediate release dosage forms if it is known that food may affect bioavailability of active drug ingredient When evaluation of C max and T max is tedious in fasting studies

36. The test meal is given as breakfast with high fat content before dosing (high calorie content of 950-1000 calories with minimum of 50% calories from fat, 15-20% from proteins and remaining from carbohydrates) The meal should be consumed approximately 15 minutes prior to dosing

37. Data evaluation

38. Record maintenance Minimum duration of 5 years after study completion or for at least 2 years after expiry date of the batch of new drug product whichever is later Retention of samples For 5 years after study conduct or 1 year after expiry date of drug whichever is later

39. Sample size = minimum 16 Statistical methods ANOVA Student t test(paired or unpaired) Chi- square test

40. Summary Definition & Importance: BA and BE studies assess the rate and extent of drug absorption, ensuring therapeutic consistency between formulations Key pharmacokinetic parameters include C max, T max , AUC 0-t and AUC 0-∞ Cross-over design, Parallel design, Replicate cross-over design, Latin square designs, Balanced incomplete block design ANOVA, Student’s t-test, and Chi-square test Study records must be kept for at least five years or two years after drug expiry

41. References Sarkar S, Srivastava V, Mohanty Postgraduate pharmacology. 2 nd ed. Paras Medical Publisher;2024 Brunton LL, Hilal-Dandan R, Knollmann BC, editors. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 14 th ed. New York: McGraw Hill; 2022 Patel D, Desai D, Mehta FA, Professor A. A Review on the Importance of In-vitro Bioavailability and Bioequivalence Studies [Internet]. 2020. Chow SC. Bioavailability and bioequivalence in drug development. Wiley Interdiscip Rev Comput Stat. 2014;6(4):304–12.

42. Questions What is reference product in BA and BE studies ? Purpose of BA and BE studies ? Methods of assessment of BA and BE ? Pharmacokinetic parameters used in BA and BE studies ? What is cross over study design ?