THE EFFECT OF TIMOLOL DROPS ON RESPIRATORY-FUNCTION

Purpose Recently, attention has been focused on the adverse drug react ions of topical timolol, especially with regard to respiratory functio n in the elderly. This study was designed to assess whether timolol ca uses an alteration in lung function in patients without pre-existing r espiratory disease and who have not suffered the impact of long-term b eta(2) blockade. Methods A placebo-controlled randomised, double-maske d, cross-over study was carried out on 20 ocular hypertensive patients with intraocular pressures over 21 mmHg, normal optic discs and full visual fields by Humphrey perimetry. Subjects received single-dose uni ts of timolol maleate 0.5% drops or normal saline drops. Both were ins tilled in one eye or systemically (sublingually). The peak expiratory flow rate (PFR), forced expiratory volume (FEV), vital capacity (VC) a nd FEV/VC (%) ratio were all measured both before and after each type of drop and route of administration. Results Two hours after instillat ion of timolol there was no change in PFR (p = 0.67) or VC (p = 0.40), but there was a fall in FEV (p = 0.038) and the FEV/VC (%) ratio (p = 0.041). The fall was greatest after topical administration. Conclusio ns Our results show that in our group of patients there was a tendency towards mild bronchial obstruction after topical timolol, although th is was not clinically significant.