Pharmacokinetics With Pregnancy

Maternal changes occur during pregnancy that can affect the metabolism of drugs.9 These include:

Increased plasma volume, which in turn can increase the volume for drug dilution Decreased albumin and increased plasma proteins due to estrogen, which can affect ratios of free and bound drugs

Increased renal blood flow and glomerular filtration rate, with subsequent influence on excretion of drugs Increased activity of hepatic mixed function oxidases, thereby directly altering drug metabolism Decreased gastric emptying, leading to interference with drug absorption

Fetal pharmacokinetics are not well established. The length of exposure to possible teratogens is an important factor; metabolites of maternal medications can be eliminated by the fetus into the amniotic fluid with subsequent fetal ingestion, gastrointestinal absorption, and elimination, thereby continuing the cycle.9 Depending on the efficacy of these various processes and the types of drugs and their metabolites, there may be enhanced or diminished fetal exposure to medications. There is no data to conclude that amni-otic fluid functions as a third-space compartment or if this could affect the dosing of medications during pregnancy. There is also no evidence to suggest that doses of chemotherapeutic agents should be altered to account for the new metabolic function in the mother.

0 0

Post a comment