A Cochrane review [Abstract] 1 included 35 trials with 27 827 healthy adults. Another Cochrane review [Abstract] 2 included 12 studies with a total of 2 494 subjects (1 586 children and adolescents and 908 elderly).
Prevention: In healthy adult population, AMT prevented 61% of influenza cases (95% CI 35% to 76%; 11 trials, n=4 645) and 25% of influenza-like-illness (ILI) cases (95% CI 13% to 36%; 15 trials, n=17 496; p<0.001 for both results) as compared to placebo. RMT demonstrated comparable effectiveness, but there were only 3 trials (n= 688) and the results for prophylaxis were not statistically significant. In children, a protective effect of AMT (RR 0.11; 95% CI 0.04 to 0.30), but no protective effect of RMT (RR 0.49; 95% CI 0.21 to 1.15) was observed. In the elderly, no protective effect of RMT was observed (RR 0.45; 95% CI 0.14 to 1.41) and there were no studies on AMT.
Treatment: In the treatment of adult´s influenza, both drugs significantly shortened duration of fever compared to placebo (AMT by 0.99 days; 95% CI 0.71 to 1.26, 10 trials, n= 542; RMT by 1.24 days, 95% CI -0.76 to -1.71, 3 trials, n=82). There was no effect on nasal shedding or persistence of influenza A viruses in the upper airways after up to five days of treatment (AMT RR 0.97; 95% CI: 0.76 to 1.24; 3 trials, n=170; RMT RR 0.68; 95% CI 0.30 to 1.53; 3 trials, n= 152). In children, RMT had benefit in the abatement of fever on day three of treatment (RR 0.36; 95% CI 0.14 to 0.91), but no protective effect of AMT was observed (RR 0.37; 95% CI 0.08 to 1.75). There were no studies on the effectiveness of AMT and RMT in the treatment of influenza A in the elderly.
Comment: The quality of evidence is downgraded by inconsistency and limitations in study quality.
Clinical comment: Due to resistance problems, amantade and rimantadine are not considered to be first-line options in the prevention or treatment of influenza. A majority of circulating A(H1N1)- ja A(H3N2) influenza viruses are resistant to these drugs.
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