Background

A and B both have antiviral properties, but they are not widely used due to incomplete knowledge of their properties and concerns about possible adverse effects. This is an update of a Cochrane review first published in 1999, and previously updated in 2006.

Objectives

To assess the effects of A and B in adults with influenza.

Search methods

We searched the Cochrane Acute Respiratory Infections Group Trials Specialized Register (15 February 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2007), MEDLINE (January 1966 to January 2007), EMBASE (January 1985 to December 2006) and reference lists of articles. We also contacted manufacturers and researchers in the field.

Selection criteria

Randomized and quasi-randomized studies comparing A and/or B with placebo, or comparing doses or schedules of A and /or B in adults with influenza.

Data collection

Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. We collected adverse effects information from the trials.

Main results

Seventeen trials involving 689 people were included. Five trials involving 234 people compared A with placebo. Compared with placebo, A significantly shortened duration of fever by 23% (by 1.00 days, 95% confidence interval 0.73 to 1.29). Six trials involving 256 people compared B with placebo. B significantly shortened duration of fever by 33% compared with placebo (by 1.27 days, 95% confidence interval 0.77 to 1.77). The small amount of information available directly comparing A and B (two trials involving 53 people) did not indicate that the efficacy of the two drugs was different, although the confidence intervals were very wide. Based on four trials of 73 people, central nervous system effects were significantly more common with A than B (relative risk 2.58, 95% confidence interval 1.54 to 4.33).

          Authors’ conclusions

A and B both appear to be effective in the treatment of influenza. There is insufficient evidence to determine whether one is more effective than the other. Both drugs appear to be relatively well tolerated, although B may be safer.