Zinc salts have low in vitro therapeutic indices against rhinoviruses, suggesting beneficial effects of zinc lozenges may not be due to selective antirhinovirus activity.
The antiviral activity of zinc salts against rhinovirus types 1A and 39 was assayed by yield reduction and inhibition of cytopathic effect in cell culture. The findings indicate that the zinc salts tested have low in vitro therapeutic indices and suggest that the possible beneficial effects of zinc lozenges in reducing cold symptoms may not be related to selective antirhinovirus activity.
Geist et al. (Wed,) studied this question.