Sildenafil

Administration

• Type: PDE-5 inhibitor
• Dosage Forms:
• Routes of Administration: PO, IV
• Common Trade Names: Viagra, Revatio

Adult Dosing

• Pulmonary hypertension: 5-20mg PO TID or 2.5-10 mg IV bolus TID
• Erectile dysfunction: 25-100mg PO 1hr prior to sexual activity, max once daily

Pediatric Dosing

Not generally recommended for chronic use in pediatric patients, but is used off-label

Special Populations

• Pregnancy Rating: B
• Lactation risk: Infant risk cannot be ruled out
• Renal dosing: no adjustment
• Hepatic dosing: no adjustment for mild-moderate impairment

Contraindications

• Allergy to class/drug
• Concurrent regular or intermittent use of any organic nitrates
• Concomitant use with HIV protease inhibitors or elvitegravir/cobicistat/tenofovir/emtricitabine
• Concomitant use with riociguat or any other guanylate cyclase stimulator

Adverse Reactions

Serious

• Myocardial infaction
• Sickle cell vasoocclusive crisis
• Ischemic optic neuropathy, retinal hemorrhage
• Hearing loss
• Priapism

Common

• Headache
• Insomnia
• Visual disturbance
• Erythema, flushing
• Indigestion
• Epistaxis, nasal congestion, rhinorrhea

Pharmacology

• Half-life: 4h
• Metabolism: Hepatic: CYP3A4 (major) and CYP2C9 (minor)
• Excretion: Mostly fecal

Mechanism of Action

• Inhibits cGMP specific phosphodiesterase type-5 (PDE5) in smooth muscle--> less cGMP breakdown--> more cGMP within vascular smooth muscle--> vascular smooth muscle relaxation--> vasodilation

See Also

• Pulmonary hypertension