Which monitoring is essential for pregnant women taking phenytoin?

Monitoring serum phenytoin levels is essential for pregnant women taking this medication because phenytoin is known to have a narrow therapeutic index. This means that the difference between the effective dose and the toxic dose is small, making it crucial to keep the drug levels within a specific range to avoid both toxicity and therapeutic failure.

Pregnancy can alter the pharmacokinetics of certain medications, including phenytoin; factors like increased blood volume, changes in protein binding, and alterations in liver metabolism can affect how the drug is processed in the body. Regular monitoring of serum levels ensures that the medication remains effective and minimizes the risk of potential side effects for both the mother and the developing fetus.

This monitoring helps to guide dosage adjustments that may be necessary during pregnancy, as physiological changes can lead to variations in how the drug is absorbed, distributed, metabolized, and excreted. By maintaining appropriate serum phenytoin levels, healthcare providers can optimize treatment and enhance the safety and well-being of both the mother and her baby.