Pulmonary pharmacology in pregnancy

The pharmacologic treatment of any pregnant patient with a respiratory illness should occur only after careful consideration of the effects of altered maternal physiology and the potential effects on the developing fetus. Pregnancy changes gastrointestinal absorption of drugs, creates an increased volume of distribution, decreases protein binding, and increases renal excretion and hepatic metabolism of most drugs. These changes may necessitate variation in dose or dosing interval of drugs administered during pregnancy. Before administration of a therapeutic agent, the available animal and human data summarizing fetal effects should be reviewed. Most of the bronchodilators and more common antibiotics used for respiratory infections have been used without adverse fetal effects. Important exceptions do exist and certain agents should be avoided. When the patient expresses concern over a pharmacologic or radiologic exposure during pregnancy, a detailed history of the type, timing, and duration of exposure and genetic consultation should be obtained. Finally, drug treatment of serious illness in the pregnant patient should not be withheld unless the risk of the agent in question clearly outweighs the fetal and maternal risk of untreated disease.