The use of once-daily dosing of gentamicin in obstetrics and gynecology

Pelvic inflammatory disease: new diagnostic criteria and treatment

PID is a common infection in reproductive-age women that presents an enormous public health and economic burden. It is responsible for much short- and long-term morbidity that may necessitate interventions subsequent to the original infection. Mild PID seems to be much more common than severe or "classic" PID, and the importance of early recognition and treatment cannot be understated. Current treatment regimens seem to be effective in terms of immediate clinical efficacy. As we learn more about the frequency and importance of subclinical PID, the true burden of upper genital tract infection upon reproductive age women continues to be elucidated.

Single daily dosing of gentamicin: pharmacokinetic comparison of two dosing methodologies for postpartum endometritis

OBJECTIVE

We compared the pharmacokinetics of two methods for dosing gentamicin for the treatment of postpartum endometritis with the goal of achieving adequate peak serum concentrations (>12 mg/L) and prolonged trough levels below 2 mg/L.

METHODS

Group-I subjects (n = 5) received intravenous gentamicin, 5 mg/kg per total body weight over 60 min., with a maximum dose of 500 mg. Group-II subjects (n = 17) were dosed intravenously according to the following formula: Dose = desired peak concentration (fixed at 14 mg/L) * (volume of distribution, i.e., 0.35 L/kg) * adjusted body weight (in kilograms). Serum gentamicin levels were obtained 1 hr. and 8-12 hr. after infusion of the second dose. Pharmacokinetic parameters for the subjects in each group were calculated according to standard formulas.

RESULTS

Subjects in Group I had significantly higher doses and peak drug concentrations (P < 0.01), while in Group II, 76% of patients had peak levels less than desired (<12 mg/L). Both groups maintained trough levels of <2 mg/L in excess of 12 hr.

CONCLUSIONS

Changing to the adjusted body weight formula for Group I, while maintaining a dose between 4 and 5 mg/kg, would reduce excessive peak concentrations. Using a calculated volume of distribution of 0.4 L/kg in Group II would improve peak serum concentrations to the desired levels. Both dosing regimens ensure adequate aminoglycoside pharmacokinetic parameters and avoid the need for monitoring serial serum drug concentrations, provided the expected clinical response is also achieved. While the first dosing formula is simpler to calculate, the second dosing formula allows for more individualized dosing considerations.