Manufacturer: GlaxoSmithKline, UK
Pharmaceutical name: Vardenafil
Pack: 4 tablets (20mg/tablet)

Levitra is a phosphodiesterase inhibitor. It works by helping to increase blood flow into the penis during sexual stimulation. This helps you to achieve and maintain an erection.

Therapeutic actions: Penile erection is caused by the engorgement of the penis with blood. This engorgement occurs when the blood vessels delivering blood to the penis increase in size and increase the delivery of blood to the penis. At the same time, the blood vessels carrying blood away from the penis decrease in size and decrease the removal of blood from the penis. Sexual stimulation that leads to the engorgement and erection causes the production and release of nitric oxide in the penis. Nitric oxide then activates the enzyme, guanylate cyclase to produce cyclic guanosine monophosphate (cGMP). The cGMP is primarily responsible for increasing and decreasing the size of the blood vessels carrying blood to and from the penis, respectively. Vardenafil prevents an enzyme called phosphodiesterase-5 from destroying cGMP so that cGMP persists longer. The longer cGMP persists, the more prolonged the engorgement of the penis.

What is it used for?: Treating erectile dysfunction (ED).

Contraindications and cautions:
Levitra is contraindicated if you:
• are allergic to Levitra’s ingredients
• have certain heart problems (eg, unstable angina, severe heart failure), low blood pressure, or uncontrolled high blood pressure
• have certain hereditary degenerative eye problems (eg, retinitis pigmentosa)
• have severe liver problems or severe kidney problems that require dialysis
• have had a heart attack, stroke, or life-threatening irregular heartbeat within the past 6 months
• are taking nitrates (eg, isosorbide, nitroglycerin) in any form (eg, tablet, capsule, patch, ointment), nitroprusside, or certain antiarrhythmics (eg, quinidine, amiodarone)
• use certain recreational drugs called "poppers" (eg, amyl nitrate, butyl nitrate)
Side effects: General: dizziness; flushing; headache; heartburn; stuffy or runny nose; upset stomach.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); back or muscle pain; chest pain; fainting; prolonged, painful erection; ringing in the ears; severe or persistent dizziness; severe or persistent vision changes; sudden hearing loss.

Interactions: Vardenafil should not be used simultaneously with any nitrate medication because this combination could result in the development of potentially life-threatening low blood pressure.