Systemic absorption and cardiovascular effects of phenylephrine eyedrops

Area of Science:

• Ophthalmology
• Pharmacology
• Cardiovascular Science

Background:

• Phenylephrine hydrochloride is commonly used in ophthalmic solutions for mydriasis.
• Vitreoretinal surgery patients may have unique systemic absorption profiles.
• Comparing different formulations of phenylephrine is crucial for patient safety.

Purpose of the Study:

• To compare the systemic absorption of 2.5% aqueous and 10% viscous phenylephrine hydrochloride ophthalmic solutions.
• To evaluate the cardiovascular effects of these two phenylephrine formulations.
• To assess the safety and efficacy of phenylephrine eyedrops in patients undergoing vitreoretinal surgery.

Main Methods:

• A study involving 24 patients undergoing vitreoretinal surgery.
• Administration of two drops of either 2.5% aqueous or 10% viscous phenylephrine hydrochloride.
• Serial plasma level measurements at 10, 20, and 60 minutes post-instillation.
• Monitoring of systolic and diastolic blood pressure.

Main Results:

• Plasma phenylephrine levels were significantly higher with the 10% viscous solution at 10, 20, and 60 minutes (P < .02).
• Mean systolic and diastolic blood pressure showed a trend towards being higher with the 10% viscous solution, but this was not statistically significant.
• Isolated cases of elevated blood pressure were observed.

Conclusions:

• The 10% viscous phenylephrine hydrochloride solution results in greater systemic absorption compared to the 2.5% aqueous formulation.
• Phenylephrine eyedrops, particularly the viscous form, should be administered with caution and under close medical observation due to potential cardiovascular effects.
• Prompt recognition and management of adverse reactions are essential following phenylephrine instillation.