AN EVALUATION OF NASAL RESPONSE FOLLOWING DIFFERENT TREATMENT REGIMESOF OXYMETAZOLINE WITH REFERENCE TO REBOUND CONGESTION

This was a randomized double-blind vehicle controlled study aimed at i nvestigating the effects on nasal function of 7 days treatment with th e topical decongestant oxymetazoline (0.05% w/v). Fifty healthy volunt eers took part in the study and these were randomly allocated to three treatment groups (i) daily oxymetazoline (b.i.d. 150 mu l per nostril ) (ii) intermittent oxymetazoline, with oxymetazoline being substitute d for vehicle at the morning doses on days 1, 3, and 7; and (iii) dail y vehicle (b.i.d. 150 mu l per nostril). The nasal airway was assessed by measurement of nasal airway resistance (NAR) using posterior rhino manometry, subjective scaling of nasal patency by means of a visual an alogue scale (VAS), and clinical visual examination. On days 1, 2, 3, and 7, NAR and VAS measurements were obtained before the morning dose and up to 6 hours after dosing; clinical visual examinations were also performed before dosing on these days. NAR and VAS measurements were also made following withdrawal of treatment on Days 8 and 9. Nonparame tric analysis of the results showed that therapeutic tolerance to oxym etazoline did not develop over the 7-day treatment period, and visual examination of the nasal mucosa failed to find significant evidence of rhinitis. Evidence of rebound nasal congestion was found following 3 days of oxymetazoline treatment, with baseline NAR within the daily an d intermittent oxymetazoline groups being significantly greater on Day 3 compared to Day 1 (p < 0.05). However, there was a trend toward inc reasing baseline NAR in the vehicle group over the course of the study , suggesting that the vehicle may have contributed to the rebound cong estion. Following the withdrawal of treatments, only the intermittent oxymetazoline group had significantly higher NAR on Days 8 and 9 compa red to Day 1 (p < 0.05). Subjective VAS measurements generally followe d trends in NAR.