How to drink xenical orlistat sildenafil affects the response to sexual stimulation. It acts by enhancing smooth muscle relaxation using nitric oxide, a chemical that is normally released in response to sexual stimulation. This smooth muscle relaxation allows increased blood flow into certain areas of the penis, which leads to an erection. It is preferable not to use Apcalis with grapefruit juice, alcoholic beverages, tobacco. If you smoke tobacco and take Apcalis concomitantly this may lead to a condition called NAION (sudden optic nerve-related vision loss). Inform your doctor before to take Apcalis if you have abnormal penis, including curved penis and birth defects of the penis, had coronary artery disease, arrhythmia, angina, heart attack or heart failure, hypo- or hypertension, bleeding, stomach ulcers, diabetes, hyperlipidemia (excess of lipids in the blood), sickle-cell anemia, liver or kidney failure in history.