++
The sale and use of drugs are regulated in almost all countries by governmental agencies. In the United States, regulation is by the Food and Drug Administration (FDA). New drugs are developed in industrial or academic laboratories. Before a new drug can be approved for regular therapeutic use in humans, a series of animal and experimental human studies must be carried out.
++
New drugs may emerge from a variety of sources. Some are the result of identification of a new target for a disease. Rational molecular design or screening is then used to find a molecule that selectively alters the function of the target. New drugs may result from the screening of hundreds of compounds against model diseases in animals. In contrast, many (so-called "me-too" drugs) are the result of simple chemical alteration of the pharmacokinetic properties of the original, prototype agent.
++
++
++
Because society expects prescription drugs to be safe and effective, governments regulate the development and marketing of new drugs. Current regulations require evidence of relative safety (derived from acute and subacute toxicity testing in animals) and probable therapeutic action (from the pharmacologic profile in animals) before human testing is permitted. Some information about the pharmacokinetics of a compound is also required before clinical evaluation is begun. Chronic toxicity test results are generally not required, but testing must be underway before human ...