In the United States new pharmaceutical products must be approved by the FDA as being both safe and effective. This process generally involves submission of an investigational new drug filing with sufficient pre-clinical data to support proceeding with human trials. Following IND approval, three phases of progressively larger human clinical trials may be conducted. Phase I generally study toxicity using healthy volunteers. Phase II can include pharfacokinetics and dosing in patients, and Phase III is a very large study of efficacy in the intended patient population.
A fourth phase of post-approval surveillance is also often required due to the fact that even the largest clinical trials cannot effectively predict the prevalence of rare side-effects. Post-marketing surveillance ensures that after marketing the safety of a drug is monitored closely. In certain instances, its indication may need to be limited to particular patient groups, and in others the substance is withdrawn from the market completely. Questions continue to be raised regarding the standard of both the initial approval process, and subsequent changes to product labeling (it may take many months for a change identified in post-approval surveillance to be reflected in product labeling) and this is an area where congress is active.
The FDA provides information about approved drugs at the Orange Book site. In the UK, the British National Formulary is the core guide for pharmacists and clinicians.Necro-Mortosis