Drug Development Process

Overview

Before any new drug formulation is marketed, it undergoes lengthy and expensive laboratory, animal, and human trials. Preclinical trials provide the basis for clinical trial testing, which occurs in humans.

Tests carried out in humans are called clinical trials, and determine whether a drug is safe and effective. For most drugs in the United States, three carefully planned stages (Phases 1-3) of clinical trials are done prior to Food and Drug Administration (FDA) approval.

As microbicide clinical trials are designed to test prevention methods, their design presents challenges different from those of drug formulations designed to treat existing illness. The three phases of clinical testing have been adapted as described below to meet the specific needs of microbicide trials.

Stages of Drug Development

Phase	Purpose	Number of volunteers	Typical length	Typical cost
1	Safety: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.	10-100 people, typically healthy	1.5 years	$10 million
2	Expanded Safety: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.	50-500 patients with the disease being studied	2 years	$20 million
3	Effectiveness: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.	300-30,000	3.5 years	$45 million

"Phase 1/2" study designs are also considered Expanded Safety Studies, and are either a combination of Phase 1 and 2 designs, or designed for Phase 1 to be a run-in to Phase 2.

"Phase 2/3" and "Phase 2/2B" study designs efficiently combine the expanded safety component of a traditional Phase 2 study with sufficient statistical power to measure microbicide effectiveness against HIV as in a Phase 3 trial. In such a trial, a specified number of participants are enrolled into the Phase 2 component of the study and followed intensively with frequent safety evaluations. Simultaneously, limited numbers of additional participants are enrolled into the Phase 3 component of the study to achieve adequate sample size.

Microbicide clinical trials often also undergo tolerance studies, typically in the male partner of the woman using the trial product, to determine acceptability of the microbicide in partners. Multiple microbicide candidates are also believed to be contraceptive: studies to determine the contraceptive effects of a microbicide are done outside of testing for HIV prevention.

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