Delayed gentamicin elimination in patients with severe preeclampsia.

Gentamicin is an aminoglycoside antibiotic frequently used in the treatment of mixed polymicrobial infections. Because patients with preeclampsia exhibit compromised renal function, decreased intravascular volume, and increased extravascular fluid, it was theorized gentamicin may be handled differently in normotensive versus preeclamptic patients. Eighteen patients with postpartum endometritis receiving gentamicin were divided into three treatment groups based on the presence and severity of preeclamptic symptoms. After the gentamicin steady state was achieved, serum samples were collected at 30, 150, and 450 minutes following completion of a timed 30-minute infusion. The mean half-life and gentamicin clearance in severe preeclamptic patients (3.15 hours and 91.5 ml/min) were significantly different from normotensive patients (2.38 hours and 135.9 ml/min) and mild preeclamptic patients (1.87 hours and 142 ml/min). No significant differences in volume of distribution were seen. A high correlation between elimination rate and distribution volume was noted in normotensive patients; however, a moderate correlation was seen in patients with preeclampsia. Therefore, alterations in renal function in patients with severe preeclampsia, and not changes in volume of distribution, may be the primary cause for delayed aminoglycoside elimination.