Question

For depot injections, in which drug is slowly released over weeks or months, which bioequivalence study design is used?

• A. Multiple dose study design.
• B. Replicated crossover study design
• C. Nonreplicate, parallel study design
• D. Randomized crossover design

Answer 1

The Correct Option is C

To determine the correct bioequivalence study design for depot injections, we need to understand the nature of depot injections and the purpose of different study designs.

Depot Injections: These are formulations designed to release a drug slowly over an extended period (weeks or months). This slow release makes it challenging to measure the drug's concentration over time using traditional pharmacokinetic models.

Bioequivalence Study Designs:

• Multiple Dose Study Design: Typically used when the drug exhibits nonlinear pharmacokinetics or has a long half-life. It involves administering multiple doses to achieve steady-state conditions. Not ideal for depot formulations due to their extended release.
• Replicated Crossover Study Design: Utilized to handle high intra-subject variability. This design requires subjects to receive each treatment more than once. However, depot injections make replication challenging due to their long-acting nature.
• Nonreplicate, Parallel Study Design: This design involves two groups of subjects, each receiving one formulation (test or reference). It is particularly useful for drugs with long half-lives or formulations that release over a long period, making it suitable for depot formulations.
• Randomized Crossover Design: Used for treatments administered in short courses. Each subject receives both treatments in a random sequence. Depot formulations, with extended drug release, are not aptly suited for this design.

Given the characteristics of depot injections and the matching requirements of study designs, the correct answer is a Nonreplicate, Parallel Study Design. This approach accommodates the extended release and prolonged pharmacokinetics of such formulations.

Conclusion: Depot injections, due to their slow and prolonged drug release characteristics, fit best with the nonreplicate, parallel study design to adequately assess their bioequivalence.