Avanafil instructions for use, how to take?

Full Prescribing Information for Avanafil

This document provides comprehensive medical guidelines for the use of Avanafil (trade names include Stendra and Spedra). It outlines the pharmacological action, dosing regimens, safety precautions, and contraindications strictly based on clinical data.

Clinical Pharmacology

Avanafil is a selective phosphodiesterase type 5 (PDE5) inhibitor used for the treatment of erectile dysfunction. Upon sexual stimulation, nitric oxide is released in the corpus cavernosum of the penis, which activates the enzyme guanylate cyclase. This results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation and blood inflow. Avanafil enhances the effect of nitric oxide by inhibiting PDE5, which is responsible for the degradation of cGMP. It has a rapid onset of action, reaching peak plasma concentrations (Tmax) within 30 to 45 minutes.

Indications and Usage

Avanafil is indicated for the treatment of erectile dysfunction (ED) in adult males. It is effective only in the presence of sexual stimulation. It is not indicated for use in women or children.

Dosage and Administration

The medication is taken orally, with or without food.

Recommended Starting Dose (100 mg)

For most patients, the starting dose is 100 mg, taken approximately 15 to 30 minutes before sexual activity.

Dose Titration

Increase to 200 mg: If the 100 mg dose provides insufficient efficacy and is well tolerated, the dose may be increased to 200 mg. This is the maximum recommended dose.
Decrease to 50 mg: The dose should be reduced to 50 mg in patients who experience adverse reactions on the 100 mg dose, or in patients initiating treatment while on stable alpha-blocker therapy.

Frequency

The maximum recommended dosing frequency is once per day.

Dosage in Specific Populations

Geriatric Patients (65+): Clinical studies suggest that while no specific adjustment is mandatory, a lower starting dose is prudent due to potential age-related decreases in hepatic or renal function.
Renal Impairment: No dosage adjustment is needed for mild to moderate renal impairment. Use in severe renal impairment is contraindicated.
Hepatic Impairment: Use with caution. Start with the lowest dose in mild impairment. Contraindicated in severe hepatic impairment.

Contraindications

Avanafil is strictly contraindicated in the following scenarios:

Nitrate Use: Administration to patients using any form of organic nitrates (e.g., nitroglycerin) is prohibited due to the risk of severe hypotension.
Hypersensitivity: Known allergy to avanafil or any of its components.
Cardiovascular Conditions: Recent heart attack or stroke (within the last 6 months), life-threatening arrhythmia, or unstable angina.
Blood Pressure: Resting hypotension (BP < 90/50 mmHg) or uncontrolled hypertension (BP > 170/100 mmHg).

Warnings and Precautions

Cardiovascular Risks Physicians should consider the cardiovascular status of their patients, as sexual activity carries a cardiac risk. Therefore, treatments for ED should not be used in men for whom sexual activity is inadvisable.

Priapism There is a risk of priapism (painful erection lasting more than 6 hours) or prolonged erection (more than 4 hours). If an erection persists for longer than 4 hours, the patient must seek immediate medical assistance to prevent permanent penile tissue damage.

Sensory Impairment In the event of sudden vision loss (NAION) or sudden hearing decrease/loss, patients should discontinue Avanafil and consult a physician immediately.

Drug Interactions

CYP3A4 Inhibitors: Avanafil is metabolized by CYP3A4. Strong inhibitors (ketoconazole, ritonavir) increase avanafil exposure significantly and are contraindicated. Moderate inhibitors require dose reduction.
Alpha-Blockers: Co-administration can lead to symptomatic hypotension. Patients should be stable on alpha-blocker therapy before starting Avanafil at the 50 mg dose.
Grapefruit Juice: Consumption should be avoided for 24 hours prior to taking Avanafil as it increases plasma drug concentrations.

Adverse Reactions

Most adverse reactions reported in clinical trials were mild to moderate in severity and transient.

Common: Headache, flushing, nasal congestion, nasopharyngitis.
Uncommon: Back pain, dizziness, nausea, fatigue, upper respiratory tract infection.

Storage and Handling

Store at room temperature (20°C to 25°C). Protect from light and moisture. Keep out of reach of children.