Gentamicin

Additional information

Pharmacokinetics and dosing

Gentamicin first-dose pharmacokinetics have been studied in patients with a suspected or documented episode of Gram-negative bacterial sepsis (23 men, 9 women; mean age 68 years). Women had a larger median volume of distribution per kilogram than men (0.50 vs. 0.40 L/kg) and a lower Cmax (15.2 vs. 18.5 mg/L), even though men and women received similar weight adjusted gentamicin doses [2]. No sex differentiation in dosing has been recommended [3].

Effects

In some settings urine cultures to identify pathogens and resistance pattern cannot always be obtained and therapy of urinary tract infections then has to be empirical. A Brazilian study analyzed urine isolates to identify suitable empirical therapy options for cystitis and urinary tract infections in relation to patient’s sex and age (1098 men, 8700 women). Drug classes analyzed was ampicillin, nitrofurantoin, fluoroquinolones (ciprofloxacin and levofloxacin), trimethoprim-sulfamethoxazole, gentamicin, and ceftriazone/cefotaxime, Women exhibited higher susceptibility values for all drug classes studied than men. For women in any age group, only nitrofurantoin and gentamicin provided adequate activity for empirical therapy (> 80% susceptibility). For men in any age group, only gentamicin was suitable for empirical therapy. In women aged over 60 years, few suitable empirical treatment options were identified [1].Resistance patterns for pathogens often differ between populations. A Portuguese retrospective analysis of urinary samples (120,691 (78%) from women and 34,898 (22%) from men) gentamicin resistance was more common in male urinary samples positive for E. coli andP. mirabilis[4].

Adverse effects

Studies report contradictory results whether women are more often affected by gentamicin-induced nephrotoxicity than men or not [5]. An analysis of two randomized double-blind controlled clinical trials of aminoglycosides (121 men, 93 women) found that female sex was associated with the development of nephrotoxicity [6]. Also, a multicenter study found a higher risk of gentamicin nephrotoxicity in women [7]. However, another hospital based study found no difference between men and women in risk of developing gentamicin-induced nephrotoxicity [8].

Reproductive health issues

Regarding teratogenic aspects, please consult the Drugs and Birth Defects Database (in Swedish, Janusmed fosterpåverkan).