Cetirizine and pseudoephedrine retard alone and in combination in the treatment of perennial allergic rhinitis: a double-blind multicentre study.

We compared the efficacy and safety of 5 mg cetirizine (CTZ), 120 mg pseudoephedrine retard (PER) and their combination (COM), given twice daily for three weeks, for the treatment of perennial allergic rhinitis. Two hundred and ten evaluable patients (97 males and 113 females) were included in the study and randomly allocated to one of three treatment groups, each of 70 patients. Nasal obstruction, sneezing, rhinorrhoea, nasal and ocular pruritus were scored each day throughout the study by patients using a symptom scale ranging from 0 (no symptom) to 3 (severe). The mean proportion of days without symptoms was higher in the COM group (11.8%) than in the CTZ (6.8%) and PER (5.1%) groups, but the differences were not statistically significant. The mean percentage of days when symptoms were absent or at most mild was significantly higher in the COM group (64.8%) than in either CTZ (45.5%; p = 0.003) or PER groups (40.6%; p = 0.0001). In addition, evaluation of symptoms by investigators and their global evaluation at the end of treatment showed statistically significant differences in favour of COM compared, to both CTZ and PER. The most frequent adverse events were somnolence in the CTZ and COM groups (8.6% and 12.9%, respectively) while insomnia was most frequent in the PER group. No clinically significant abnormalities were found in haematological or biochemical tests. These results indicate that the combined treatment was more effective than and as well tolerated as treatment with each individual agent