Phenylephrine eye drops do not cause clinically significant changes in blood pressure or heart rate, according to a meta-analysis published in JAMA Ophthalmology
. Phenylephrine, a sympathomimetic, is used in eye drops to dilate the pupil and is available in pharmacies as an over-the-counter conjunctival decongestant.
When the medicine is taken systemically, it can cause pronounced increases in blood pressure and there is uncertainty about whether this effect is also true of the topical preparation.
Researchers at the University of Melbourne analysed data from eight randomised controlled trials (n=916) examining the cardiovascular effects of topical phenylephrine. At a concentration of 2.5%, there was no increase in blood pressure or heart rate at 20, 30 or 60 minutes post-administration. At a concentration of 10%, there was a transient, minimal increase in blood pressure at five and ten minutes after administration (mean difference +15 mm Hg; 95% confidence interval 11.94–18.54, P<0.001), with a return to baseline at 20, 30 and 60 minutes. Heart rate increased by 4.48 beats per minutes at 20 and 30 minutes after administration (95% CI 1.09–7.88, P=0.01) but decreased again at the 60 minute mark.
The researchers say the effects of phenylephrine 2.5% are not clinically relevant and the changes seen with phenylephrine 10% are short-lived. Therefore, phenylephrine 2.5% is “safe to use in clinical routine”, they conclude.