Brand Viagra (sildenafil citrate) is indicated for:

• Treatment of erectile dysfunction (ED) in men
• Management of pulmonary arterial hypertension (PAH)
• Enhancement of erectile response to sexual stimulation

Mechanism of Action:

• Potentiates nitric oxide-mediated smooth muscle relaxation
• Increases blood flow to penile tissues during sexual arousal
• Does not produce spontaneous erections without stimulation

Dosage & Administration

• Standard ED dose: 50mg taken 30-60 minutes before sexual activity
• Dosing range: 25-100mg based on individual response/tolerance
• Maximum frequency: Once per 24-hour period
• Administration notes:
  • Avoid high-fat meals (may delay absorption)
  • Grapefruit products should be avoided
  • Tablet should be swallowed whole with water

Important Precautions

• Cardiovascular assessment recommended before use
• Caution required in patients with:
  • Anatomical penile deformities
  • Conditions predisposing to priapism
  • Severe hepatic/renal impairment
  • Left ventricular outflow obstruction
• Visual changes should be promptly reported
• Postural hypotension may occur (rise slowly from sitting position)

Absolute Contraindications

• Concurrent nitrate therapy (including recreational amyl nitrites)
• Hypersensitivity to sildenafil or excipients
• Concomitant use with guanylate cyclase stimulators
• Recent stroke/MI (within last 6 months)
• Uncontrolled arrhythmias
• Severe hepatic impairment (Child-Pugh C)
• Hypotension (<90/50 mmHg)
• Hereditary degenerative retinal disorders

Potential Adverse Effects

Common (≥1% incidence):

• Headache
• Flushing
• Dyspepsia
• Nasal congestion
• Visual color distortion
• Dizziness

Serious (require immediate medical attention):

• Priapism (>4 hours duration)
• Sudden hearing loss
• Non-arteritic anterior ischemic optic neuropathy
• Severe cardiovascular events
• Hypotensive syncope
• Hypersensitivity reactions

Significant Drug Interactions

Contraindicated combinations:

• All nitrate preparations
• Riociguat

Use with caution:

• Alpha-adrenergic blockers
• Strong CYP3A4 inhibitors (e.g., ritonavir, ketoconazole)
• Antihypertensives
• Moderate CYP3A4 inducers

Storage & Stability

• Store at controlled room temperature (20-25°C)
• Protect from moisture and light
• Maintain in original packaging
• Keep out of reach of children/pets

Patient Counseling Points

• Sexual activity may increase cardiac risk
• Medication does not protect against STDs
• Natural sexual stimulation required for effect
• Avoid excessive alcohol consumption
• Report any erection lasting >4 hours
• Discontinue use and seek medical attention for:
  • Sudden vision/hearing changes
  • Chest pain during sexual activity
  • Severe dizziness/nausea

Note: This medication should only be used under medical supervision. Regular follow-up is recommended to assess treatment efficacy and safety.