För mycket Viagra. Ser man i blått då?

Viagra is effective on erectile dysfunction because it inhibits phosphodiesterase 5 (PDE-5), an enzyme that enhances the effects of nitric oxide, which is released during sexual stimulation to relax the smooth muscle of the penis and facilitate blood inflow. However, the drug also has a milder inhibiting effect on PDE-6, an enzyme actively present in retinal photoreceptors. This causes an increase in the concentration of cyclicGMP, resulting in a depolarization of the rod cell – and increased light sensitivity and the infamous "blue vision.

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