| Clinical Trial Phases Applicable to Microbicides | |||
|---|---|---|---|
| Phase | Number of Participants | Length of Treatment and Follow-up | Objectives |
| Phase I | 10–100 | 1 to 2 weeks | To assess local and systemic safety and acceptability and to determine dose and formulation. May run into a phase II trial (called phase I/II). |
| Phase II | 50–200 | 2 to 6 months | To assess safety and acceptability over a longer time. |
| Phase II/IIb | 50–500 | 6 months to 2 years | To screen for products reaching a minimum level of effectiveness. Smaller, less costly than phase III, but numbers of participants and length of follow-up indicate whether a subsequent larger trial would be worthwhile. If so, participants continue from one trial to the next, and additional participants are recruited (called phase II/III). |
| Phase III | 1,000–30,000 | 1 to 2 years | To evaluate effectiveness in preventing HIV infection and other STIs and to assess long-term safety and acceptability. Some phase III trials will involve multiple products, which will require more participants than those testing only one product. |
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Note: Phases I/II, II/IIb, and II/III are variants of study designs or studies that move from one clinical trial phase to the next. Number of participants and length of treatment and follow-up vary. Sources: Adapted from Stone, 2003 (112), Fleming, 2004 (27), Mauck et al., 2001 (71), and the Alliance for Microbicide Development, 2004 (3). Info Reports |
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