Antihistaminic treatment of allergic rhinitis: a double-blind study with terfenadine versus dexchlorpheniramine.

A double-blind study was carried out in 65 patients with seasonal rhinitis to compare the effectiveness and tolerance of terfenadine and dexchlorpheniramine. Patients were allocated at random to receive treatment for 1 week with either 60 mg terfenadine twice daily or 2 mg dexchlorpheniramine maleate 3-times daily. Before and after treatment, patients underwent RAST and skin prick tests for reactivity to pollen and those who were positive also had rhinomanometric measurements made of nasal resistance. Diary cards were used by patients to record the severity of nasal obstruction, rhinorrhoea, sneezing, watery, irritated and red eyes, itching of the nose, throat and eyes, and cough. Details were also kept of the frequency and severity of any side-effects. Pollen counts were taken daily during the treatment period. The results showed that both terfenadine and dexchlorpheniramine produced good or excellent relief of the main symptoms in 78% and 73% of the patients, respectively. There was no significant correlation between the pollen count and reduced symptom severity. Both drugs produced a reduction in total nasal resistance but this was not significantly different from initial values, neither was there a significant difference between treatment. Terfenadine was well tolerated and side-effects incidence was significantly lower (p less than 0.01) than in patients treated with dexchlorpheniramine, particularly so with reference to drowsiness.