Management decisions regarding poisoning or envenoming in the pregnant or lactating patient take into consideration the risks to the fetus or infant of the poisoning or its treatment. Pregnancy-induced physiological changes impact on drug pharmacokinetics and pharmacodynamics in the following ways:
- Absorption: Delayed gastric emptying and intestinal transit time slow drug absorption and may prolong the period where decontamination is of potential benefit
- Distribution: Increased blood volume (45 – 50%) increases volume of distribution and potentially decreases plasma levels; dilution of plasma proteins increases free drug levels
- Elimination: Hepatic enzyme systems are altered by circulating hormones; renal blood flow and glomerular filtration rate increase.
References
- Anderson GD. Pregnancy-induced changes in pharmacokinetics. A mechanistic-based approach. Clinical Pharmacokinetics 2005; 44(10):989-1008.
- McElhatton PR, Sullivan FM, Volans GN. Paracetamol overdose in pregnancy: analysis of the outcomes of 200 cases referred to the teratology information service. Reproductive Toxicology 1997; 10:85-94.
- Syme MR, Paxton JW, Keelan JA. Drug transfer and metabolism by the human placenta. Clinical Pharmacokinetics 2004; 43(8):487-514.
- Wiles JM, Clark LE, Herrera JL. Acetaminophen overdose in pregnancy. Southern Medical Journal 2005; 98(11):1118-1122.
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