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

Comments

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