How does the body weight of the pregnant woman affect pharmacokinetics?

Increased body weight can necessitate dosage adjustments for medications due to the changes in pharmacokinetics that occur during pregnancy. As a woman's body weight increases, there are corresponding changes in body composition, including increased blood volume, fat mass, and water retention. These alterations can impact the distribution, metabolism, and elimination of drugs.

For example, a higher volume of distribution may require higher doses for hydrophilic medications, as they disperse within a larger fluid compartment. Similarly, changes in liver function and renal clearance during pregnancy may influence how drugs are metabolized and excreted. Understanding these pharmacokinetic changes is essential for ensuring therapeutic efficacy and minimizing the risk of adverse effects, making dosage adjustments based on body weight critical in the management of medication for pregnant women.