The new H1-receptor antagonist
levocabastine is the most potent
antihistamine available, as shown in classical animal tests for
antihistamine activity. Its effects also are very specific, with doses as high as 40,000 times the effective
antihistamine dose not displaying other pharmacological effects. In nasal and ocular provocation tests,
levocabastine nasal spray and
eye drops protected against
allergen-induced nasal and ocular symptoms. Twenty-three clinical trials have been performed with
levocabastine nasal spray in 1363 patients with
allergic rhinitis. At a dose of two sprays per nostril twice daily (if necessary to be increased up to four times daily),
levocabastine was significantly better than placebo and as good as or slightly better than
cromoglycate in alleviating nasal symptoms. Good to excellent results were reported in about 60% of patients on
levocabastine, compared with 37% with placebo and 47% with
cromoglycate.
Levocabastine eye drops were studied in 21 clinical trials including 1218 patients with
allergic conjunctivitis. One drop per eye twice daily (up to four times daily) provided significantly better symptom control than placebo and similar effects as those observed with
cromoglycate. Response rates were 71-80% with
levocabastine, 55% with placebo and 76% with
cromoglycate.
Levocabastine has a fast onset of action, with 94% of patients experiencing symptom relief within 15 min after the first instillation of
levocabastine eye drops. Three long-term studies (10-16 weeks' duration) showed absence of tachyphylaxis during prolonged treatment with
levocabastine. The incidence of adverse experiences was similar for
levocabastine,
cromoglycate and placebo, for
nasal spray as well as
eye drops.(ABSTRACT TRUNCATED AT 250 WORDS)