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Single-dose antibiotic therapy: what has the past taught us?
1Hôpital Claude Bernard, France.
Abstract:
The proper dosage schedule of antibiotics has generally been determined empirically, due to the difficulty of clinical trials. Initially, the dosage was chosen to allow high sustained levels greater than MIC in the blood. Antibiotics (beta lactams, tetracyclins, macrolides) were given at high doses three to six times daily, whatever their kinetic properties. The data obtained by Eagle3 with beta lactams in animal models of streptococcal and treponemal infections outlined the importance of interval between doses on the in vivo efficacy. They also showed that increasing the dose of penicillin had a positive effect on the bactericidal activity only through the persistence of effective levels (greater than MIC) at the site of infection. Further illustrations were given through experimental and clinical studies with beta lactams or other compounds on different types of infections: LRTIs, UTIs, meningitis, and endocarditis. The importance of both dynamic (i.e., pattern of bactericidal effect) and kinetic (elimination half-life) parameters was thus further identified. Information on toxicity with some compounds with a narrow therapeutic index, such as aminoglycosides, indicated that increasing the dose to enhance efficacy had some limitations. This led to numerous studies on the relations between concentration and toxicity, stating that nephro- or ototoxicity were not directly related to peak level in serum. Experimental studies showed that OD administration of aminoglycosides was both more efficient and less toxic than the multiple-dose regimen of the same daily amount. Economic considerations progressively justified attempts to both reduce the dose and the work load related to multiple administrations.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Antibiotic dosing has evolved from empirical high doses to optimized schedules. Understanding pharmacokinetic and pharmacodynamic properties improves efficacy and reduces toxicity for better patient outcomes.
Area of Science:
- Pharmacology
- Infectious Diseases
- Clinical Microbiology
Background:
- Antibiotic dosage regimens were historically determined empirically, often prioritizing high, sustained blood levels above the minimum inhibitory concentration (MIC).
- Common antibiotic classes like beta-lactams, tetracyclines, and macrolides were administered multiple times daily, irrespective of their pharmacokinetic profiles.
Observation:
- Early studies with beta-lactams in animal models highlighted the critical role of dosing intervals in achieving in vivo efficacy.
- Increasing penicillin dosage primarily enhanced bactericidal activity by prolonging the duration of drug levels above the MIC at the infection site.
- Clinical and experimental data across various infections (e.g., LRTIs, UTIs, meningitis) underscored the significance of both dynamic (bactericidal effect patterns) and kinetic (elimination half-life) parameters.
Findings:
- For antibiotics with a narrow therapeutic index, such as aminoglycosides, dose escalation for efficacy is limited by toxicity concerns (nephrotoxicity, ototoxicity).
- Research indicates that aminoglycoside nephro- and ototoxicity are not solely dependent on peak serum concentrations.
- Once-daily (OD) administration of aminoglycosides demonstrated superior efficacy and reduced toxicity compared to multiple daily doses of the same total daily amount.
Implications:
- Optimizing antibiotic dosing based on pharmacokinetic/pharmacodynamic (PK/PD) principles is crucial for maximizing therapeutic benefits while minimizing adverse effects.
- The shift towards optimized dosing strategies, including once-daily regimens for certain antibiotics, offers potential for improved patient outcomes and reduced healthcare costs.
- Further research into PK/PD relationships can refine antibiotic therapy, leading to more effective and safer treatment protocols for a wide range of infections.