Pharmacokinetics of cefotetan in patients with end-stage renal failure on maintenance dialysis

Recurrent urinary tract infections among women: comparative effectiveness of 5 prevention and management strategies using a Markov chain Monte Carlo model

BACKGROUND

Recurrent urinary tract infections (UTIs) are a common problem among women. However, comparative effectiveness strategies for managing recurrent UTIs are lacking.

METHODS

We performed a systematic literature review of management of women experiencing ≥3 UTIs per year. We then developed a Markov chain Monte Carlo model of recurrent UTI for each management strategy with ≥2 adequate trials published. We simulated a cohort that experienced 3 UTIs/year and a secondary cohort that experienced 8 UTIs/year. Model outcomes were treatment efficacy, patient and payer cost, and health-related quality of life.

RESULTS

Five strategies had ≥2 clinical trials published: (1) daily antibiotic (nitrofurantoin) prophylaxis; (2) daily estrogen prophylaxis; (3) daily cranberry prophylaxis; (4) acupuncture prophylaxis; and (5) symptomatic self-treatment. In the 3 UTIs/year model, nitrofurantoin prophylaxis was most effective, reducing the UTI rate to 0.4 UTIs/year, and the most expensive to the payer ($821/year). All other strategies resulted in payer cost savings but were less efficacious. Symptomatic self-treatment was the only strategy that resulted in patient cost savings, and was the most favorable strategy in term of cost per quality-adjusted life-year (QALY) gained.

CONCLUSIONS

Daily antibiotic use is the most effective strategy for recurrent UTI prevention compared to daily cranberry pills, daily estrogen therapy, and acupuncture. Cost savings to payers and patients were seen for most regimens, and improvement in QALYs were seen with all. Our findings provide clinically meaningful data to guide the physician-patient partnership in determining a preferred method of prevention for this common clinical problem.

Pharmacokinetic differences between the epimers of cefotetan disodium after single intravenous injection in healthy Chinese volunteers

The pharmacokinetic behaviors of the epimers of cefotetan disodium (R-CTT, S-CTT) after a single intravenous injection dose in healthy Chinese volunteers were explored in this study. In an open-label, randomized, three-way, cross-over study, 12 volunteers (6 females and 6 males) received a cross-over fashion doses of 0.5, 1.0, and 2.0 g of cefotetan disodium, separated by washout periods of 7 days. The plasma concentrations of both epimers were measured by validated high-performance liquid chromatography assays. Pharmacokinetic parameters of R-CTT, S-CTT, and total-CTT (R + S mixture) were calculated using a noncompartmental analysis. Generally, the R and S epimers showed different pharmacokinetic behaviors. Following 0.5, 1.0, and 2.0 g doses of cefotetan disodium, values of the total area under the plasma concentration-time curve (AUC(0-∞)) were 124.23 ± 19.54, 231.34 ± 39.34, and 459.09 ± 80.65 for R-CTT; 100.95 ± 14.19, 193.80 ± 30.42, and 372.66 ± 67.32 for S-CTT, respectively. Total body clearance values were 4.13, 4.43, and 4.46 L/h for R-CTT and 5.05, 5.28, and 5.50 L/h for S-CTT, respectively. Mean plasma elimination half-life (t (1/2)) values of R-CTT were 4.16, 4.13, and 4.01 h for 0.5, 1.0, and 2.0 g doses, respectively, and those of S-CTT were 3.15, 3.25, and 3.21 h. There were significant differences in t (1/2) between the two epimers (P < 0.05). The t (1/2) of R-CTT was 28% longer than that of S-CTT, which indicated that the elimination of the S-CTT was greater than that of the R-CTT. All treatments were well tolerated.

Clinical pharmacokinetics of cefotetan

Cefotetan is a 7-alpha-methoxy beta-lactam. A long serum half-life and resistance to beta-lactamase hydrolysis have made cefotetan an attractive chemotherapeutic agent, and the results of clinical trials worldwide have demonstrated its efficacy in a wide variety of clinical situations. Cefotetan can be administered intravenously (bolus or infusion) or intramuscularly with lidocaine (lignocaine) 0.5%. Mean peak plasma concentrations are almost linearly related to dose. The volume of distribution is between 8 and 13L and is not different from other cephalosporins. No accumulation is seen after repeated doses and no metabolite has been detected in either plasma or urine. Total body clearance is 1.8 to 2.9 L/h. Renal clearance accounts for about 64 to 84% of a dose, and 75% of a dose is excreted in the urine within 24 hours. The plasma elimination half-life is between 3 and 4 hours after intravenous and intramuscular doses. Half-life is considerably prolonged in patients with renal impairment (up to 10 hours). Cefotetan concentrations are likely to be active against susceptible bacteria in most tissues and body fluids. Breast milk and cerebrospinal fluid concentrations are low. The recommended dosage is 1g every 12 hours, increasing to 2g in severe infections and 3g in life-threatening infections. In surgical prophylaxis, a single dose of 2g is given with the induction of anaesthesia; an additional dose of 2g may be administered 12 hours later. In children over 6 months, the recommended dosage is 30 mg/kg given 12-hourly. In patients with a creatinine clearance of 10 to 40 ml/min (0.6 to 2.4 L/h), the dose is halved or the dosage interval is doubled. When creatinine clearance is less than 10 ml/min (0.6 L/h), the dose is quartered or the dosage interval quadrupled.

Considerations in dosage selection for third generation cephalosporins

Pharmacokinetic parameters of third generation cephalosporins vary widely, requiring different dosage regimens and adjustment methods for each agent. Although their antibacterial spectrum favours their usage in infections caused by aerobic Gram-negative organisms, due to their limited post-antibiotic effect against these organisms, dosage regimens should ensure that free drug concentrations at the site of infection remain above the minimum inhibitory concentration for as much of the dosage interval as possible in patients with normal host defence mechanisms and for the entire dosage interval in immunocompromised patients. Altered protein binding encountered in various disease states can affect both microbiological and pharmacokinetic properties especially for drugs with high protein binding. Since the concentrations at the site of action are often different from those in serum, a higher or lower range of dosages needs to be selected depending on the target site. Decreased renal function affects the elimination of most third generation cephalosporins, whereas the presence of hepatic disease does not generally necessitate dosage adjustment. Because of the complex age-related physiological changes in paediatric and elderly patients, dosage should be adjusted on the basis of the reported pharmacokinetic data in these populations. The usual recommended dose may or may not be optimal in a given condition depending on the complex interactions between pharmacokinetic, microbiological and other host factors.