Dose-dependency and time-course of electrophysiologic short-term effects of VIAGRA® : a case study

• Published in: Documenta ophthalmologica Vol. 110; no. 2-3; pp. 247 - 254
• Main Authors: JÄGLE, Herbert, JÄGLE, Christine, SEREY, Ludwig, SHARPE, Lindsay T
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01-03-2005; Springer Nature B.V
• Subjects: 3',5'-Cyclic-GMP Phosphodiesterases - antagonists & inhibitors; Adult; Biological and medical sciences; Blood Pressure - drug effects; Color Perception - drug effects; Dose-Response Relationship, Drug; Electroretinography - drug effects; Follow-Up Studies; Humans; Male; Medical sciences; Ophthalmology; Phosphodiesterase Inhibitors - administration & dosage; Phosphodiesterase Inhibitors - pharmacokinetics; Piperazines - administration & dosage; Piperazines - pharmacokinetics; Purines; Reference Values; Retina - drug effects; Retina - physiopathology; Sildenafil Citrate; Sulfones; Time Factors; Vision disorders; Short term; Biological fluid; PDE-inhibitor; Vision disorder; Citrate; B wave; Posology; Blood; Electrodiagnosis; Test; Arterial pressure; Blood pressure; Ophthalmology; Oscillatory potential; A wave; Electroretinography; Human; Drug; Cone; Tritanopia; sildenafil citrate; Flicker; color vision; Case study; Eye disease; Recording; ERG; Dyschromatopsia
• ISSN: 0012-4486; 1573-2622
• DOI: 10.1007/s10633-005-0653-3

The dose-dependency and time-course of the short-term visual effects of sildenafil citrate (VIAGRA) were tested in two subjects. Blood pressure was measured and samples of blood taken at 30 min intervals before and after drug administration. In the first experiment, prolongations of the implicit times of the scotopic maximum a-wave, cone a- and b-wave, 33 Hz flicker, ON-response a- and b-wave and 3.3 Hz a- and b-wave electroretinogram (ERG) recordings and of the oscillatory potentials OP1, OP2, and OP3 were observed for both eyes of both subjects, following 100 or 200 mg dosings. Interestingly, no prolongation was found for OP4, to which the OFF-bipolar cell pathway significantly contributes. In the second experiment, in which visual function was repeatedly assessed following a 200 mg dose, similar prolongations were found in both eyes of one subject for the implicit times of the oscillatory potential OP2, the cone b-wave response and the 3.3 Hz a-wave. Moreover, the steady-state (A0) and immediate extinction (B0) blue target thresholds of transient tritanopia were raised relative to the pre-drug administration baseline effects. While the maximum lowering of both systolic and diastolic blood pressure approximately correlated with the peak plasma concentration of sildenafil (c. 30-60 min after administration), the peak magnitudes of most visual effects were found at c. 110 min, consistent with a second compartment kinetic.