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Bacampicillin hydrochloride: chemistry, pharmacology, and clinical use.

Bacampicillin hydrochloride is an orally administered ester of ampicillin that is rapidly and completely hydrolyzed in vivo to ampicillin. The most notable advantage of bacampicillin over ampicillin is its superior bioavailability--bacampicillin achieves significantly higher blood and tissue levels and attains peak blood levels more rapidly than equimolar doses of oral ampicillin. In addition, the percentage of an oral dose of ampicillin that is absorbed decreases sharply as the size of the dose is increased from 500 mg to 2 g; this phenomenon is not observed with equipotent doses of bacampicillin. The enhanced absorption of bacampicillin in the upper gastrointestinal tract results in a frequency of diarrhea that appears to be markedly lower than that of ampicillin and similar to that observed with amoxicillin. Apart from the sizable differences between bacampicillin and ampicillin with regard to oral absorption, the pharmacokinetic and pharmacologic profiles of these two agents are essentially identical. Twice daily dosing (pulse dosing) with bacampicillin has been shown in numerous clinical trials to be of equivalent efficacy to ampicillin given four times daily or amoxicillin given three times daily in the treatment of infections of the upper respiratory tract, lower respiratory tract, skin and soft tissues, and urinary tract. The unanswered question is whether twice daily ampicillin or amoxicillin would yield similar results.

Absorption↗

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Protein binding: what does it mean?

Protein binding can enhance or detract from a drug's performance. As a general rule, agents that are minimally protein bound penetrate tissue better than those that are highly bound, but they are excreted much faster. Among drugs that are less than 80-85 percent protein bound, differences appear to be of slight clinical importance. Agents that are highly protein bound may, however, differ markedly from those that are minimally bound in terms of tissue penetration and half-life. Drugs may bind to a wide variety of plasma proteins, including albumin. If the percentage of protein-bound drug is greater when measured in human blood than in a simple albumin solution, the clinician should suspect that the agent may be bound in vivo to one of these "minority" plasma proteins. The concentration of several plasma proteins can be altered by many factors, including stress, surgery, liver or kidney dysfunction, and pregnancy. In such circumstances, free drug concentrations are a more accurate index of clinical effect than are total concentrations. Formulary committees must grasp the clinical significance of qualitative and quantitative differences in protein binding when evaluating competing agents.

Anti-Bacterial Agents↗