The FDA assigns the letters A, B, C, D, and X to drugs approved for human use. These classifications are about: (AIIMS May 2009)
|A||Amount of dosage reduction needed as serum creatinine clearances fall|
|B||Amount of dosage reduction needed in presence of liver dysfunction|
|C||Fetal risk when given to pregnant women|
|D||Relative margins of safety / therapeutic index|
a. These are pregnancy classifications. Drugs in pregnancy Category A have been evaluated in controlled clinical studies in all trimesters, and. they are deemed safe enough to pose only a remote risk of fetal harm. With categories B, C, and U, there is increasing evidence, whether from animal or human studies (or both), of increasing risks.
b. Drugs in Category D have demonstrable risk, but may be used when, for example, the purpose is to manage a life-threatening condition and no safer alternatives are available. Notice of such must be included in the package insert’s Warning section.
c. Classification X also means proven fetal harm, but the risks of administering to a pregnant woman far exceed the potential benefits.
d. This warning is put in the Contraindications section of the package insert.