How long should antibiotic therapy last? An increasing number of clinical studies on the use of antibacterial drugs in various nosologies are currently devoted to the study of this question. It has long been clear to all clinicians that the "usual" duration of antibiotic therapy (7, 10, 14, etc. days) is based solely on convenience from the generally accepted schedule point of view, and not at all on scientific data. Reducing the duration of antibiotic therapy courses is an important area of research, due to the spread of antibiotic resistance, the possible development of secondary infection and toxic reactions with excessively long treatment cycles with antibacterial drugs.

In this regard, a group of scientists from the University of Louisiana (United States) in collaboration with Ortho-McNeil Pharmaceutical, a respiratory fluoroquinolone levofloxacin company in the American pharmaceutical market, conducted a multicenter randomized double-blind study to evaluate the efficacy and safety of levofloxacin at a dose of 750 mg once daily for 5 days compared to a dose of 500 mg daily for 10 days with community-acquired pneumonia of varying severity (from mild to severe) in adult patients.

Patients were randomized 1: 1 into the two groups listed above and stratified by severity of pneumonia.

The study did not include patients with pleural empyema, suspected meningitis, renal failure, probable fatal outcome within 72 hours, quinolone allergies, neutropenia, women infected with HIV , pregnant or nursing.

Patients underwent traditional clinical, microbiological and serological examinations, the effectiveness of the treatment was evaluated according to clinical and microbiological criteria 7-14 days after taking the last dose of levofloxacin.

A total of 530 patients were randomized, but 2 of them did not receive therapy with the investigational drug, 37 were withdrawn from the study due to the development of adverse events. As a result, group I (750 mg levofloxacin 5 days) included 256 patients, and group II (500 mg levofloxacin 10 days) included 272 patients. Unfortunately, out of 437 patients who completed administration of the study drug, only 319 patients were able to assess the clinical efficacy of therapy in accordance with the protocol; the other patients did not attend the follow-up visit. A microbiological efficacy evaluation was performed in 195 patients in whom the etiology of pneumonia was determined.

By comparing the groups of patients, it was found that in approximately 40% of the patients in each group, the severity of pneumonia corresponded to classes III-IV on the PSI scale (Pneumonia Severity Index - pneumonia gravity index), in none group I patient and only 3 group II patients there was class V severity pneumonia on a PSI scale.

The indicators of overall clinical efficacy were equivalent in the two groups: 92.4% in group I and 91.1% in group II. There was a tendency to relapse in group II patients (4.3% vs 1.2%). The frequency of eradication of "typical" and "atypical" pathogens at the end of treatment was more than 90% in both groups. In one patient, P.aeruginosa (levofloxacin MPC = 4.0 mg / L) was isolated during follow-up. In group I patients, a subjective improvement in the condition and a normalization of the temperature on the 3rd day of treatment were more often observed. Treatment failure rates were similar in the two groups (3.5%).

Adverse events (headache, nausea, insomnia, diarrhea) were slightly expressed and the same in the two groups.

The study was well planned and well executed, but unfortunately included 2 variables - the dose and the duration of treatment, which made the interpretation of the results somewhat difficult. However, based on current ideas on the pharmacokinetics and pharmacodynamics of dose-dependent fluoroquinolones (i.e. their efficacy depends on the ratio between the maximum concentration of the drug in blood serum and the minimum inhibitory concentration - the BMD of the drug in relation to the pathogen, or the ratio of the area under the pharmacokinetic curve "concentration-time" to IPC), the appointment of these antibiotics at higher doses should make it possible to reduce the treatment time without reducing its efficiency. Additional studies are needed to assess whether this will slow the development of antibiotic resistance, reduce toxicity or the risk of developing secondary infection in patients.