Ticarcillin vs carbenicillin: clinical pharmacokinetics

Area of Science:

• Pharmacology
• Clinical Pharmacy

Background:

• Carbenicillin is a penicillin antibiotic.
• Ticarcillin is a semisynthetic penicillin with enhanced activity against Pseudomonas compared to carbenicillin.

Purpose of the Study:

• To compare the pharmacokinetic characteristics of ticarcillin and carbenicillin in healthy volunteers.
• To determine the clinical significance of observed pharmacokinetic differences.

Main Methods:

• Intravenous infusion of 2 gm of ticarcillin and carbenicillin in 12 healthy volunteers.
• Comparison of serum levels, biologic half-life, volume of distribution, and urinary recovery.
• Assessment of probenecid's effect on pharmacokinetics and protein binding.

Main Results:

• Ticarcillin had a lower initial serum level but similar levels to carbenicillin after 2 hours.
• Ticarcillin exhibited a slightly longer biologic half-life and larger volume of distribution.
• Urinary recovery was 86% for ticarcillin and 99% for carbenicillin within 24 hours.

Conclusions:

• Despite minor pharmacokinetic differences, ticarcillin and carbenicillin pharmacokinetics are broadly similar.
• Observed differences in half-life, distribution, and protein binding are unlikely to be clinically significant.
• Probenecid significantly increased serum levels, half-life, and volume of distribution for both antibiotics.