Generic
Sildenafil
85 brands available in the market
At a glance
Sildenafil is a PDE5 inhibitor used for erectile dysfunction and pulmonary arterial hypertension. It increases blood flow to the penis during sexual stimulation by raising cGMP levels in the corpus cavernosum.
Description
Sildenafil is a selective, reversible inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). When sexual stimulation causes local release of nitric oxide, PDE5 inhibition by sildenafil increases cGMP levels in the corpus cavernosum, resulting in smooth muscle relaxation and increased blood flow, producing an erection.
Indications
- Erectile dysfunction (ED)
- Pulmonary arterial hypertension (PAH)
Therapeutic class
Drugs for Erectile Dysfunction
Pharmacological class
PDE5 Inhibitor
Pharmacology
Sildenafil inhibits PDE5 enzyme, preventing cGMP degradation in the corpus cavernosum. During sexual stimulation, NO release leads to increased cGMP levels, which relaxes smooth muscles and dilates penile arteries, increasing blood flow and causing erection.
Mechanism of action
Increases cGMP in the corpus cavernosum to enhance blood flow and produce erection.
Dosage
Adult Dose (Oral):
- ED: 50 mg 1 hour before sexual activity; 25-100 mg based on tolerability; max 100 mg/dose, once daily
- Elderly (>65): Start with 25 mg
- Hepatic/Renal impairment: Start with 25 mg
- PAH: 20 mg 3 times daily (4-6 hours apart)
Administration
- Take with or without food
- Can be taken 30 minutes to 4 hours before sexual activity
- Swallow tablet whole; do not chew, crush, or break
- Do not take more than once daily
Missed dose
If you miss a dose, take it as soon as possible; if almost time for the next dose, skip it; do not double the dose.
Side effects
Common Side Effects:
- Flushing, headache
- Dizziness, blurred vision
- Muscle pain, stomach upset
- Rash, nasal congestion
Serious (Rare):
- Prolonged erection (>4 hours)
- Sudden hearing loss
- MI, stroke, cardiac arrhythmia
Precautions & warnings
- Do not use with organic nitrates (severe hypotension)
- Caution in severe cardiovascular disease, MI/stroke within 6 months
- Caution in anatomical penile deformities or predisposition to priapism
- Caution in retinitis pigmentosa
- Caution with alpha-blockers (hypotension)
Contraindications
- Hypersensitivity to sildenafil or any component
- Concurrent use with organic nitrates in any form
Drug interactions
- Nitrates and nicorandil: Potentiate hypotensive effects
- Alpha-blockers: Hypotension (caution)
- CYP3A4 inhibitors (ritonavir, ketoconazole, erythromycin): Decreased sildenafil clearance
- CYP3A4 inducers (rifampicin): Decreased plasma concentrations
- Beta-blockers: Symptomatic hypotension
Food interactions
Alcohol is unsafe with Sildenafil (increases side effect risk).
Use in pregnancy
Use in Pregnancy: Sildenafil is not indicated for women; no adequate data; consult your doctor.
Pregnancy Category: D — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Sildenafil is not indicated for women; no adequate data; consult your doctor.
Pediatric use
Safety and efficacy not established in children
Geriatric use
Elderly (≥65): Start with 25 mg
Renal / hepatic impairment
Renal Impairment: CrCl <30: Start with 25 mg; consult your doctor.
Hepatic Impairment: Caution in severe liver disease; dose adjustment may be needed; consult your doctor.
Overdose effects
Doses up to 800 mg showed increased adverse events; provide standard supportive measures; hemodialysis not effective.
Storage conditions
Store in a dry place, away from light and heat; keep out of reach of children.
Chemical structure
Sildenafil