Antivirals for the common cold.
BACKGROUND
The common cold is a ubiquitous short and usually mild illness for which preventive and treatment interventions have been under development since the mid-40s. As our understanding of the disease has increased, more experimental antivirals have been developed. This review attempts to draw together experimental evidence of the effects of these compounds.


OBJECTIVE
To identify, assemble, evaluate and (if possible) synthesise the results of published and unpublished randomised controlled trials of the effects of antivirals to prevent or minimise the impact of the common cold.


METHODS
We searched electronic databases, corresponded with researchers and handsearched the archives of the MRC's Common Cold Unit (CCU).


METHODS
We included original reports of randomised and quasi-randomised trials assessing the effects of antivirals on volunteers artificially infected and in individuals exposed to colds in the community.


METHODS
We included 241 studies assessing the effects of Interferons, interferon-inducers and other antivirals on experimental and naturally occurring common colds, contained in 230 reports. We structured our comparisons by experimental or community setting.


RESULTS
Although intranasal interferons have high preventive efficacy against experimental colds (protective efficacy 46%, 37% to 54%) and to a lesser extent against natural colds (protective efficacy 24%, 21% to 27%) and are also significantly more effective than placebo in attenuating the course of experimental colds (WMD 15.90, 13.42 to 18.38), their safety profile makes compliance with their use difficult. For example, prolonged prevention of community colds with interferons causes blood-tinged nasal discharge (OR 4.52, 3.78 to 5.41). Dipyridamole (protective efficacy against natural colds 49%, 30% to 62%), ICI 130, 685 (protective efficacy against experimental colds 58%, 35% to 74% ), Impulsin (palmitate) (protective efficacy against natural colds 44%, CI 35% to 52% ) and Pleconaril (protective efficacy against experimental colds 71%, 15% to 90% ) appear to have important antiviral properties and are well-tolerated. The evidence of effectiveness of other compounds in the treatment of experimental or natural colds is sparse.


CONCLUSIONS
There are no licensed effective antivirals for the common cold. Because prolonged intranasal administration causes a clinical picture which is not distinguishable from the common cold, interferons have no place in everyday use. Further assessment of the effects of dipyridamole, palmitate, ICI 130, 685, Impulsin and Pleconaril in preventing the common cold should be carried out. Given the multi-agent nature of the causes of the common cold, future research efforts should focus on non virus-specific compounds.
Jefferson
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Health Reviews Ltd, 35 Minehurst Road, Mytchett, Camberley, Surrey, UK, GU16 6JP. toj1@aol.com, tjefferson@cochrane.co.uk
Tyrrell
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D000281:Administration, Intranasal; D000998:Antiviral Agents / Q000627:therapeutic use*; D003139:Common Cold / Q000188:drug therapy*; D006801:Humans; D007369:Interferon Inducers / Q000627:therapeutic use; D007372:Interferons / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic
D000998:Antiviral Agents; D007369:Interferon Inducers; D007372:Interferons