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Oscar A. Candia, Rosana Gerometta; Sildenafil Increases Intraocular Pressure And Reduces Systolic Blood Pressure In Human Volunteers. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1525.
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© ARVO (1962-2015); The Authors (2016-present)
After the introduction of Viagra, two studies reported that 1) no clinical abnormalities were observed in IOP of subjects receiving up to 150 mg of Sildenafil1; 2) at the maximum therapeutic dose of 100 mg, sildenafil did not produce any significant acute change in IOP in men with chronic open-angle glaucoma, nor any change in blood pressure2. These results were contrary to our findings that in sheep, 50 and 100 mg of sildenafil substantially increased IOP3. Our purpose was to repeat a study in human volunteers in the City of Corrientes, Argentina to corroborate the effects of sildenafil on human IOP and systolic BP.
Nine healthy volunteers (male and female, 18 to 74 years old) were selected for the study after cardio-vascular evaluation. The subjects were informed that they would take a pill and might feel weak for 2 hrs. The subjects signed an informed-consent form approved by local agencies, which also follow ARVO recommendations. IOP was measured with a Goldman applanation tonometer by an ophthalmologist, who did not know which of the subjects ingested 100 mg sildenafil (Vorst, Laboratorios Bernabo, Argentina) or placebo. IOP & BP were measured before ingestion of the agent, 80 min after and 5 hrs later. In an additional group of 5 subjects, three received placebo and two 100 mg sildenafil.
In the group of 9, IOP before sildenafil was 13.1±0.6, which increased to 16.5± 0.8 mm Hg (p< 0.01) 80 min later. IOP returned to control values (12.7± 0.6) 3 hrs later. Systolic BP was 118 ±4.3 and 97±4.1 before and 60-90 min after sildenafil respectively, a 21 mm Hg decrease. Systolic BP was no different than control 3 hrs later. In the group of 5 subjects, IOP significantly increased in those receiving sildenafil but not in those who took the placebo, with similar results for BP. The probability of this outcome by chance is 1/32 or about 3%.
Sildenafil increased IOP and decreased BP in human volunteers on a time course consistent with its erectile effect. It suggests that the muscle of pre-capillaries arterioles of the ciliary body contains PDE5. These results support our hypothesis that the open communication between the ciliary body stroma and the anterior chamber would allow a fluid flow in either direction, such that a vasodilator-evoked increase in plasma-like fluid into the AC likely accounts for the IOP elevation. This type of vasodilator could increase IOP of senior patients who are administered these compounds for vascular diseases. 1Am J Ophthalmol 2000;129:675; 2Am J Ophthalmol 2001;132:872; 3Invest Ophthalmol Vis Sci 2010;51:3139.
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