Ampicillin

Additional information

Pharmacokinetics and dosing

No studies with a clinically relevant sex analysis regarding the pharmacokinetics of ampicillin have been found, except in pregnant women and in children. The pharmacokinetics of ampicillin-sulbactam in pediatric patients (19 males, 9 females, age 3 months-12 years) have shown to be similar [2].Due to changes in half-life and volume of distribution of ampicillin during pregnancy, concentrations of ampicillin have been shown to be lower in pregnant than non-pregnant women. In pregnant women receiving a single i.v. injection of 1 g ampicillin in combination with 500 mg sulbactam before delivery, half-lives of ampicillin and sulbactam were reduced (35-40 min and ~30 min, respectively). However, the authors reported that peak concentrations were similar to values observed in young men [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].In another study of urinary E. coliisolates (2 274 men, 32 265 women) age- and sex-specific antibiotic susceptibility patterns for ampicillin, amoxicillin clavulanate, ciprofloxacin, nitrofurantoin and trimethoprim-sulfamethoxazole were investigated. Ampicillin susceptibility was similar in men and women (66.0% vs. 66.3%). Age-specific susceptibilities differed between men and women for all antibiotics studies except trimethoprim-sulfamethoxazole. However, the magnitude of the observed differences was generally less than 5% and the authors suggest that they may not represent clinically meaningful differences [4]. Similar findings were presented in another study, where distribution of E. coliresistance to ampicillin according to age was similar in men and women, although men had slightly higher percentage of resistance [5].

Among risk factors associated with isolation of ampicillin-sulbactam resistant to E. coliin hospitalized patients (602 men, 507 women), female sex (for nonsurgical patients) was observed as a risk factor (odds ratio 5.14). The authors suggest that this finding likely reflects the lower prevalence of urinary tract infections in men than in women [6].

In a prospective study of ampicillin treatment for gonorrhea (1915 men, 921 women), the proportion of failure of treatment with ampicillin 1 g daily was higher among men than women (10.6 vs. 3.8%). Failure was defined as cases with positive cultures within 14 days after treatment regardless of previous negative cultures during the first week. When a combination of ampicillin and probenecid was used (1 or 2 g), women had higher failure rates [7].

Adverse effects

No studies with a clinically relevant sex analysis regarding adverse effects of ampicillin have been found.

Reproductive health issues

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