Vardenafil works by selectively inhibiting the enzyme phosphodiesterase type 5 (PDE5), which is responsible for breaking down cyclic guanosine monophosphate (cGMP). cGMP is a key mediator of smooth muscle relaxation and blood vessel dilation. The mechanism of action involves:

1. Erectile Dysfunction:
   • During sexual stimulation, nitric oxide (NO) is released in the penile tissue, which activates the enzyme guanylate cyclase.
   • This increases the production of cGMP, leading to relaxation of smooth muscles in the penile arteries and increased blood flow to the corpus cavernosum, resulting in an erection.
   • By inhibiting PDE5, vardenafil prevents the breakdown of cGMP, enhancing and prolonging the erectile response.

Vardenafil is highly selective for PDE5, which minimizes its effects on other phosphodiesterase enzymes and reduces the risk of side effects.

Vardenafil is approved for the following condition:

1. Erectile Dysfunction (ED):
   • Treatment of erectile dysfunction in adult men, including those with diabetes or who have undergone prostate surgery.

The dosage of vardenafil varies depending on the patient’s response and tolerability. Below are general guidelines:

1. Adults:
   • Standard Dose: 10 mg taken orally approximately 25–60 minutes before sexual activity. The dose may be adjusted to 5 mg or 20 mg based on efficacy and tolerability.
   • Maximum Frequency: Once daily.
2. Special Populations:
   • Elderly: Start with a lower dose (5 mg) due to potential increased sensitivity.
   • Renal Impairment: No dose adjustment is needed for mild to moderate impairment. Use with caution in severe renal impairment.
   • Hepatic Impairment: Start with a lower dose (5 mg) in patients with mild to moderate hepatic impairment. Avoid use in severe hepatic impairment.
3. Administration:
   • Vardenafil can be taken with or without food, but high-fat meals may delay its absorption.

Avoid excessive alcohol consumption while taking vardenafil, as it may increase the risk of side effects

Vardenafil is generally well-tolerated, but some side effects may occur. These include:

1. Common Side Effects:
   • Headache
   • Flushing
   • Nasal congestion
   • Dyspepsia (indigestion)
   • Dizziness
2. Less Common Side Effects:
   • Nausea
   • Back pain
   • Muscle pain
   • Visual disturbances (e.g., blurred vision, changes in color perception)
3. Rare but Serious Side Effects:
   • Priapism: Prolonged and painful erection lasting more than 4 hours. This is a medical emergency and requires immediate treatment.
   • Sudden Hearing Loss: Rare cases of hearing impairment have been reported.
   • Cardiovascular Events: Hypotension, myocardial infarction, or stroke, particularly in patients with pre-existing cardiovascular disease.

Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION): Sudden vision loss in one or both eyes

1. Contraindications:
   • Hypersensitivity to vardenafil or any component of the formulation.
   • Concurrent use of nitrates (e.g., nitroglycerin) or nitric oxide donors, as this can cause severe hypotension.
   • Severe cardiovascular disease (e.g., unstable angina, recent myocardial infarction).
2. Warnings:
   • Cardiovascular Risk: Use with caution in patients with a history of cardiovascular disease, as sexual activity may increase cardiac workload.
   • Priapism: Patients should seek immediate medical attention if an erection lasts longer than 4 hours.
   • Vision or Hearing Loss: Discontinue vardenafil and consult a healthcare provider if sudden vision or hearing loss occurs.
3. Monitoring:
   • Monitor for signs of hypotension, especially in patients taking antihypertensive medications.
   • Regular cardiovascular assessment in patients with pre-existing heart conditions.

Vardenafil interacts with several medications, including:

1. Nitrates (e.g., nitroglycerin): Concurrent use can cause severe hypotension and is contraindicated.
2. Alpha-Blockers (e.g., doxazosin): May cause additive hypotensive effects.
3. Protease Inhibitors (e.g., ritonavir): Increase vardenafil levels, requiring dose adjustment.
4. CYP3A4 Inhibitors (e.g., ketoconazole, erythromycin): Increase vardenafil levels, increasing the risk of side effects.
5. Antihypertensive Medications: May cause additive hypotensive effects.

Vardenafil is available under its generic name as well as brand names. Some common formulations include:

• Generic Name: Vardenafil hydrochloride
• Brand Names: Levitra (standard formulation), Staxyn (orodispersible tablet).