This document discusses study designs for bioequivalence studies. It describes the three main study designs: crossover design, parallel design, and multiple-dose design. The crossover design involves each subject receiving both the test and reference treatments in random order separated by a washout period. The parallel design assigns different groups of subjects to either the test or reference treatment. The multiple-dose design gives multiple doses of the same drug to reach steady state levels. Key elements of bioequivalence study design include selection of subjects, determining sample size, defining the washout period, randomization, data collection, statistical analysis, and ethical and regulatory considerations.

1. Study Design in
Bioequivalence Studies
Presented by:
Gaurav Patil
R. C. Patel Institute of Pharmaceutical
Education & Research
2022-23
Department of Pharmaceutical Analysis

2. Agenda
Introduction
Need for Bioequivalence Studies
Study Designs
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3. Bioequivalence
Bioequivalence is defined as the absence of a significant difference in the rate and
extent to which the active ingredient or active moiety in pharmaceutical equivalents or
pharmaceutical alternatives becomes available at the site of drug action when
administered at the same molar dose under similar conditions in an appropriately
designed study.
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4. Need for Bioequivalence Studies
Objectivity and Validity
Controlling Variability
Statistical Power
Ethical Considerations
Regulatory Compliance
Reducing Resource Wastage
Ensuring Reproducibility
Feasibility Assessment
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5. Study designs for bioequivalence :-
1. Crossover Design
2. Parallel Design
3. Multiple-dose Design
• Terminologies in study design
Selection of Subjects
Sample Size Determination
Washout Period
Randomization
Administration of Treatments
Data Collection
Statistical Analysis
Ethical Considerations
Regulatory Submission
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6. 1. Crossover Design:
• In a crossover design, each participant receives both the test and reference treatments in a
random sequence.
• A complete crossover design is usually employed, in which each subject receives the test
drug product and the reference product. Examples of Latin-square crossover designs for a
bioequivalence study in human volunteers.
• There is a washout period between the two treatment periods to eliminate any residual
effects of the previous treatment.
• The time intervals should be spaced so that the peak blood concentration, the total area
under the curve, and the absorption and elimination phases of the curve may be well
described.
• A two-period study is a study that is performed on two different days (time periods)
separated by a washout period during which most of the drug is eliminated from the body.
• This design reduces inter-subject variability and requires a smaller sample size.
• Drugs with high within-subject variability generally have a wide therapeutic window and
despite high variability, these products have been demonstrated to be both safe and
effective.
• Replicated crossover designs are used for the determination of individual bioequivalence, to
estimate within-subject variance for both the test and reference drug products, and to
provide an estimate of the subject-by-formulation interaction variance.
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8. 2. Parallel Design:
• In a parallel design, different groups of participants are assigned to receive either the test or
reference treatment.
• Parallel design is used for drug products that contain drugs that have a long elimination half-
life or drug products such as depot injections in which the drug is slowly released over
weeks or months.
• In this design, two separate groups; One group will be given the test product and the other
group will be given the reference product.
• Blood sample collection time should be adequate to ensure completion of gastrointestinal
transit (approximately 2–3 days) of the drug product and absorption of the drug substance.
• This design is less efficient in terms of sample size but may be preferred in certain situations
where the crossover design is not feasible or ethical.
3. Multiple-dose Design:
• Multiple doses of the same drug are given consecutively to reach steady state plasma drug
levels.
• The multiple-dose study is designed as a steady-state, randomized, two-treatment, two-way,
crossover study comparing equal doses of the test and reference products in healthy adult
subjects.
• Each subject receives either the test or the reference product separated by a “washout”
period, which is the time needed for the drug to be completely eliminated from the body.
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9.  Selection of Subjects:
• Eligibility Criteria: Define inclusion and exclusion criteria for selecting participants. This may
include factors like age, gender, health status, and concomitant medications.
• Healthy Volunteers: Bioequivalence studies typically involve healthy volunteers who do not have
the condition the drug is intended to treat.
 Sample Size Determination:
• Statistical Power: Calculate the required sample size to achieve adequate statistical power based
on expected variability and desired level of significance.
 Washout Period:
• Define the duration of the washout period between the administration of the test and reference
treatments. The washout period allows sufficient time for the drug to be eliminated from the body,
minimizing any carryover effects.
 Randomization:
• Randomly assign participants to receive the test or reference treatment first in a crossover
design. Randomization helps reduce selection bias and ensures an unbiased comparison
between the treatments.
 Administration of Treatments:
• Drug Dosing: Administer the test and reference treatments following the approved dosing
regimen.
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10.  Data Collection:
• Pharmacokinetic (PK) Parameters: Collect blood or plasma samples at predetermined time
points to measure PK parameters
 Statistical Analysis:
• Compare PK Parameters: Use appropriate statistical methods (e.g., ANOVA, linear mixed-
effects models) to compare PK parameters of the test and reference treatments.
• Bioequivalence Criteria: Evaluate whether the 90% confidence interval of the ratio of geometric
means for Cmax and AUC falls within the predefined bioequivalence acceptance range (usually
80%-125%).
 Ethical Considerations:
• Ethical Approval: Ensure the study protocol is approved by an ethics committee or institutional
review board (IRB).
 Regulatory Submission:
• Companies are required to submit comprehensive study reports along with other supporting
documents as part of the regulatory approval process for generic drugs.
• The study reports should follow the International Conference on Harmonisation (ICH) guidelines
and contain sufficient data and analysis to demonstrate bioequivalence.
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11. Thank you