Levocabastine. An update of its pharmacology, clinical efficacy and tolerability in the topical treatment of allergic rhinitis and conjunctivitis.

Levocabastine is a potent and selective histamine H1-receptor antagonist which has been evaluated as a topical treatment (nasal spray and/or eyedrops) for allergic rhinitis and/or conjunctivitis. Data available at the time of the previous review in Drugs, together with more recent results, have clearly demonstrated that levocabastine nasal spray and eyedrops are clinically effective, have a rapid onset of action and are well tolerated in patients with nasal and/or ocular allergic conditions. Previous evidence indicating that topical levocabastine has efficacy similar to or better than that of topical sodium cromoglycate (cromolyn sodium) has been confirmed in more recent studies. Furthermore, results from a number of controlled clinical trials have also shown that topical levocabastine is at least as effective as oral terfenadine for the treatment of allergic rhinoconjunctivitis. Notably, topical levocabastine appears to be more effective than oral terfenadine in improving the severity of selected symptoms. Limited data indicating efficacy equivalent to that of oral loratadine, oral cetirizine or azelastine nasal spray will need to be confirmed. Data from several studies have shown that topical levocabastine has a tolerability profile similar to that of placebo, topical sodium cromoglycate or oral terfenadine. The main adverse events seen in patients treated with topical levocabastine are ocular irritation after application of eyedrops, and headache, nasal irritation, somnolence and fatigue after administration of the nasal spray. Administered doses of topical levocabastine, and subsequent plasma concentrations, are low, and the risk of systemic adverse events is therefore expected to be minimal. Thus, topical administration of levocabastine rapid and effective symptom relief with no apparent serious adverse events in patients with allergic rhinitis and/or conjunctivitis. Topical levocabastine is a useful alternative to topical sodium cromoglycate or oral terfenadine. Additional data supporting current evidence that topical levocabastine can provide more effective symptom relief than oral terfenadine, together with clarification of the relative efficacies of these agents in relation to varying pollen exposure, would help to further confirm its clinical potential. However, the results available to date suggest that the topical formulations of levocabastine are a valuable treatment option in patients with allergic rhinitis and/or conjunctivitis.