Myrtol standardized (Gelomyrtol forte) is a phytotherapeutic extract (distillate) consisting mainly of three monoterpenes: (+)alpha-pinene, d-limonene and 1,8-cineole.

Objective: This study describes and compares the efficacy, safety and tolerability of a 2-week treatment with myrtol stand. (4 x 300 mg, day 1-14), cefuroxime (CAS 55268-75-2) (2 x 250 mg daily for day 1-6), ambroxol (CAS 18683-91-5) (3 x 30 mg for day 1-3, 2 x 30 mg for days 4-14) and matched placebo in acute bronchitis.

Patients: 676 male and female outpatients, aged > or = 18 years, with acute bronchitis of recent onset (within last 5 days), with an FEV1 > 75% of the normal EGKS-value and without evidence or suspicion of chronic pulmonary disease or any further confounding illness were included in the study.

Intervention: Patients were randomly assigned to a 2-week treatment course with either myrtol stand. (N = 170), cefuroxime (N = 171), ambroxol (N = 163) or placebo (N = 172) in a double-blind, placebo-matched, parallel-group fashion. Evaluations were at baseline (visit 1), after 1 and 2 weeks of treatment (visits 2 and 3) and at 2 weeks after conclusion of the treatments (visit 4).

Criteria: Responder- and non-responder rates (primary), signs (abnormal auscultation), symptoms (daily diary data on nightly cough, coughing fits during the day, sputum consistence and general well-being; visit data on bronchial hyperreactivity and absence/presence of associated symptoms), FEV1, overall efficacy, absence of relapse, safety and tolerability (adverse events, laboratory screens, vital signs and physical examination). Criteria were evaluated for the intention-to-treat data-set (ITT) and the 'efficacy evaluable' sample (EAP), i.e. excluding patients with missing values (incl. discontinued non-responders and drop-outs for other reasons) at the time of assessment.

Results: The signs and symptoms of acute bronchitis regressed readily in all treatment groups, but regression was slower and less complete in the patients treated with placebo. In patients treated with placebo, the acute bronchitis was considered to have deteriorated to such an extent that discontinuation was indicated ('non-responder') in 36 patients (ITT: 20.9%, 95% CI: 15.1 to 27.8% and EAP: 21.3%, CI: 15.4 to 28.3%) after 1 week (visit 2) and in 19 further patients (ITT: 11.0%, CI: 6.8 to 16.7%; EAP: 14.8%, CI: 9.2 to 22.2%) after 1 further week (visit 3). In contrast, in the group of patients treated with myrtol stand. the non-responder rates at visits 2 and 3 were only 5.3% (ITT, CI: 2.4 to 9.8%; EAP: 5.4%, CI: 2.5 to 10.0%) and 1.2% (ITT, CI: 0.1 to 4.2%; EAP: 1.3%, CI: 0.2 to 4.7%); the responder rates at visit 2 were statistically significantly higher (p < 0.001) for myrtol stand. (ITT: 92.9%, CI: 88.0 to 96.3) compared to placebo (ITT: 77.3%, CI: 70.3 to 83.4), and similar to those for cefuroxime (ITT: 92.4%, CI: 87.4 to 95.9) and ambroxol (ITT: 89.6%, CI: 83.8 to 93.8%). The superiority of the active treatments vs. placebo with little difference among the treatments was confirmed for all further criteria of evaluation. There was no evidence of bronchoconstriction or relapse in any treatment group for the patients continuing treatment (i.e. for those who were not discontinued because of non-response). The treatments were safe and comparably well tolerated.

Conclusion: Compared to placebo, treatment with myrtol stand. was well tolerated but evidently superior in terms of efficacy, resulting in a more rapid and more complete recovery; although well comparable with the other active treatments, myrtol stand. tended to be superior to cefuroxime and ambroxol for several ancillary criteria. Myrtol stand. is a well-evidenced alternative to antibiotics for acute bronchitis without specified infective agent, without the risk to promote the development of bacterial resistance.