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Effect of probenecid on the excretion of ampicillin in human bile
Abstract:
1. Ampicillin concentrations were determined in serum and bile after intravenous injection into patients with T-tube bile drainage of 1 gram ampicillin before and during probenecid medication. The concentrations were followed up to fifteen hours after injection.2. Probenecid increased the half-life of ampicillin in serum from 74 minutes to 137 minutes.3. Ampicillin concentrations in bile were higher following probenecid medication and a concentration over 5 mug/ml was obtained for 3 h longer than before probenecid.4. The ampicillin concentrations in bile were approximately the same as those in serum both before and during probenecid medication suggesting passive transport of ampicillin from blood to bile.5. A combined treatment of ampicillin and probenecid might be of clinical value in the therapy of cholangitis and typhoid carriers.
Insights
Probenecid significantly enhances ampicillin levels in both serum and bile, prolonging its half-life and increasing biliary concentrations. This combination may benefit patients with cholangitis and typhoid carriers.
Area of Science:
- Pharmacology
- Hepatology
- Infectious Diseases
Background:
- Ampicillin is a widely used antibiotic.
- Understanding its pharmacokinetics in bile is crucial for treating biliary infections.
- Probenecid is known to affect drug excretion.
Purpose of the Study:
- To investigate the effect of probenecid on ampicillin concentrations in serum and bile.
- To determine the clinical implications of combined ampicillin and probenecid therapy.
Main Methods:
- Intravenous administration of ampicillin (1 gram) to patients with T-tube bile drainage.
- Measurement of ampicillin serum and bile concentrations before and during probenecid medication.
- Pharmacokinetic analysis, including half-life determination.
Main Results:
- Probenecid increased ampicillin's serum half-life from 74 to 137 minutes.
- Bile ampicillin concentrations were higher with probenecid, maintaining >5 mug/ml for an additional 3 hours.
- Serum and bile ampicillin concentrations were similar, suggesting passive transport from blood to bile.
Conclusions:
- Probenecid enhances ampicillin's pharmacokinetic profile in both serum and bile.
- Combined ampicillin and probenecid therapy shows potential clinical utility for cholangitis and typhoid carriers.
- Passive diffusion appears to be the primary mechanism for ampicillin transport into bile.