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.