Elevation of intraocular pressure by calcium channel blockers
J. F. Beatty, T. Krupin, P. F. Nichols and B. Becker
Topical administration of three different calcium channel blockers
(verapamil hydrochloride, diltiazem hydrochloride, or nifedipine) increased
intraocular pressure transiently in rabbits. Outflow facility and
episcleral venous pressure were unchanged. Aqueous humor flow seemed to be
increased 30 minutes after topical application of verapamil when estimated
by the Goldmann equation or by changes in anterior chamber
fluorescein-labeled dextran concentration. However, aqueous humor ascorbate
concentrations and turnover of radioactive iodide did not differ from that
in the untreated eye. Ocular blood volume was found to be increased after
topical application of verapamil, which suggested vascular changes as a
possible mechanism for the induced increase in IOP. Topical verapamil
raised IOP in healthy human volunteers, but the elevation was less than
observed in rabbits. Single oral doses of verapamil in rabbits or human
beings had no effect on IOP.
