Metipranolol-induced adverse reactions: II. Loss of intraocular pressure control

This paper reviews the behaviour of intraocular pressure (IOP) in glaucomatous eyes treated with metipranolol with and without drug-induced adverse reactions (ADRs). Two hundred and forty seven patients with open angle glaucoma who were receiving the three different strengths of metipranolol (0.1%, 0.3%, and 0.6%) in our Department and the 7 patients who participated in the metipranolol rechallenge trial were included in this study. Out of the 247 patients, there were 52 eyes of 29 patients who showed 78 episodes of ADRs associated with metipranolol. Forty five of these 78 episodes (57.6%) were associated with loss of IOP control. Two of the 7 eyes treated with metipranolol in the rechallenge trial showed loss of IOP control, 1 of them without any signs of ocular inflammation. We further studied all the glaucomatous eyes controlled with metipranolol 0.6% only and 22 eyes were identified with loss of IOP control but without recognisable signs or symptoms of ADR. Five other eyes in this group later developed metipranolol-induced ADRs. The possible pathophysiological mechanisms for the loss of IOP control are discussed and it is suggested that the active drug, metipranolol, could be directly implicated.