Need quick, reliable information on Sildenafil? Consult Medscape’s drug reference for detailed prescribing information, including dosage, contraindications, and potential adverse effects. This resource provides a wealth of clinically relevant data, directly from reputable sources.
Specifically, Medscape highlights Sildenafil’s mechanism of action as a potent phosphodiesterase-5 (PDE5) inhibitor, explaining its role in treating erectile dysfunction and pulmonary arterial hypertension. Pay close attention to potential drug interactions, particularly with nitrates, which can cause a dangerous drop in blood pressure. Always review patient history carefully before prescribing.
Remember: Medscape offers more than just drug information. Explore their extensive collection of medical articles, clinical guidelines, and continuing medical education (CME) resources to deepen your understanding of Sildenafil’s clinical application and patient management strategies. Safe and effective use requires a thorough grasp of both benefits and risks.
Key takeaway: Medscape’s concise and evidence-based approach simplifies access to critical information. Use it as a cornerstone of your research, but always consider individual patient circumstances and consult relevant guidelines for the most appropriate treatment strategy.
Sildenafil: Mechanism of Action and Pharmacokinetics
Sildenafil inhibits phosphodiesterase type 5 (PDE5), an enzyme that breaks down cyclic guanosine monophosphate (cGMP). Increased cGMP levels relax smooth muscle in the corpus cavernosum, facilitating penile erection in response to sexual stimulation. This effect is specific; Sildenafil doesn’t cause erections without sexual stimulation.
Absorption and Distribution
Oral bioavailability of Sildenafil is approximately 40%. Peak plasma concentrations occur within 30-120 minutes of oral administration. It’s highly protein-bound (approximately 96%), predominantly to albumin. Distribution into tissues varies; significant concentrations are found in the lungs, liver, kidneys, and penis.
Metabolism and Excretion
Sildenafil is primarily metabolized by hepatic cytochrome P450 isoenzymes, mainly CYP3A4 and CYP2C9. The major metabolite, N-desmethyl sildenafil, also inhibits PDE5. Elimination is primarily via feces (approximately 80%) and urine (approximately 13%). The terminal elimination half-life is approximately 4 hours. This means it takes around four hours for half the drug to be removed from the body.
Pharmacokinetic Considerations
Renal and hepatic impairment significantly alters Sildenafil pharmacokinetics. Lower doses may be needed for patients with these conditions. Concomitant use with strong CYP3A4 inhibitors (like ketoconazole) increases Sildenafil plasma concentrations, potentially leading to increased side effects. Conversely, strong inducers (like rifampin) decrease plasma concentrations, potentially reducing efficacy. Always carefully assess a patient’s medical history before prescribing.
Sildenafil: Clinical Indications and Contraindications
Sildenafil primarily treats erectile dysfunction (ED) in adult men. It facilitates penile erection by increasing blood flow.
Clinical Indications: The FDA approves sildenafil for ED and pulmonary arterial hypertension (PAH). For ED, it’s prescribed when lifestyle changes and other treatments prove inadequate. In PAH, sildenafil improves exercise capacity and reduces symptoms.
Contraindications: Avoid sildenafil if you have a history of myocardial infarction, stroke, or unstable angina. It’s also contraindicated for individuals with uncontrolled hypertension or hypotension. Use caution if taking nitrates, as the combination can cause dangerously low blood pressure. Patients with severe hepatic or renal impairment should avoid sildenafil. Those with certain retinal conditions, such as retinitis pigmentosa, should also avoid this medication. Women and children should not use sildenafil.
Note: This information offers a summary. Always consult a healthcare professional before starting any new medication to ensure its suitability for your specific circumstances and to discuss potential side effects. They can assess your individual health status and provide personalized recommendations.
Sildenafil: Adverse Effects and Dosage Considerations
Begin with the lowest effective dose (25 mg) to minimize side effects. Most common side effects include headache, flushing, nasal congestion, and visual disturbances. These usually are mild and transient.
Headache is frequently reported; hydration and over-the-counter pain relievers often help.
Visual disturbances, such as blurred vision or changes in color perception, require careful monitoring. If these are severe or persistent, discontinue use and contact your doctor.
Gastrointestinal issues, including dyspepsia and diarrhea, can occur. Taking Sildenafil with food may mitigate this.
Rare but serious side effects include sudden vision loss, prolonged erection (priapism), and heart-related problems. Seek immediate medical attention if any of these occur.
Dosage adjustments are needed for certain patient groups. For example, individuals with hepatic or renal impairment require lower doses to avoid adverse reactions. Your doctor will tailor the dosage to your specific health status.
Sildenafil interacts with certain medications, notably nitrates. Combining them can cause a dangerous drop in blood pressure. Inform your doctor about all medications you take.
Always follow your doctor’s instructions and prescribed dosage. Do not exceed the recommended dose. Regular monitoring and open communication with your healthcare provider are key for safe and effective Sildenafil use.
