Sildenafil Dosage

Usual Adult Dose for Erectile Dysfunction

Initial (oral): 50 mg orally administered as needed 1 hour prior to anticipated sexual activity. A maximum of one dose per day is recommended.
Maintenance (oral): 25 to 100 mg orally as needed 30 minutes to 4 hours prior to anticipated sexual activity. A maximum of one dose per day is recommended.

Usual Adult Dose for Pulmonary Hypertension

20 mg orally three times a day taken at least 4 to 6 hours apart
or
10 mg (corresponding to 12.5 mL) administered as an intravenous bolus injection three times a day. A 10 mg dose of the injection is predicted to provide pharmacological effect of sildenafil and its N-desmethyl metabolite equivalent to that of a 20 mg oral dose. The injection is for the continued treatment of patients with pulmonary arterial hypertension (PAH) who are currently prescribed oral sildenafil and who are temporarily unable to take oral medication.

Usual Geriatric Dose for Erectile Dysfunction

25 mg orally as needed 1 hour prior to anticipated sexual activity.

Usual Pediatric Dose for Pulmonary Hypertension

Safety and effectiveness of sildenafil in pediatric pulmonary hypertension patients have not been established. Limited pediatric information exists; most pediatric literature consists of case reports or small studies; further studies are needed.

Neonates: Note: A wide range of doses and interpatient variability has been reported; careful dose titration is necessary.

Pulmonary hypertension: Reported range: 0.5 to 3 mg/kg/dose orally every 6 to 12 hours; the largest study was a double-blind, randomized, placebo-controlled trial and used an initial dose of 3 mg/kg/dose every 6 hours in 31 patients; earlier studies used 0.3 to 2 mg/kg/dose every 6-24 hours; duration not established.

Pulmonary hypertension, facilitation of inhaled nitric oxide wean: 0.3 mg/kg/dose orally given once 70 to 90 minutes prior to inhaled nitric oxide discontinuation was used in three patients. Multiple dose therapy in neonates and infants has been reported consisting of 0.22 to 0.47 mg/kg/dose every 6 hours (average duration: 28 days) to facilitate weaning from inhaled nitric oxide in patients who previously failed; duration not established.

Older than 1 yr:
Pulmonary hypertension:
Initial dose: 0.25 to 0.5 mg/kg orally every 4 to 8 hours, increase if needed and if tolerated to 1 mg/kg/dose every 4 to 8 hours; doses as high as 2 mg/kg/dose every 4 hours have been used in several case reports; a wide range of doses has been reported, duration not established. A retrospective trial of 25 patients with chronic lung disease reported treatment duration of 28 to 950 days (median: 241 days).

Pulmonary hypertension, facilitation of inhaled nitric oxide wean (in patients who have not previously failed inhaled nitric oxide wean): Single dose: 0.4 mg/kg/dose (range: 0.3 to 0.5 mg/kg/dose) given once 60 minutes prior to inhaled nitric oxide discontinuation was used in 15 patients (median age: 5.6 months).

Renal Dose Adjustments

Erectile dysfunction:
CrCl less than 30 mL/min: 25 mg orally as needed 1 hour prior to anticipated sexual activity.

Pulmonary arterial hypertension:
No dose adjustments are required for renal impaired patients (including severe renal impairment with creatinine clearance less than 30 mL/min).

Liver Dose Adjustments

Erectile dysfunction:
25 mg orally as needed 1 hour prior to anticipated sexual activity.

Pulmonary arterial hypertension:
No dose adjustments are required for hepatic impaired patients (Child Pugh class A and B).

Dialysis

Erectile dysfunction:
25 to 50 mg orally following hemodialysis 1 hour prior to anticipated sexual activity as needed.

Pulmonary arterial hypertension: Give doses after hemodialysis.

Other Comments

Sildenafil at recommended doses has no effect in the absence of sexual stimulation.

Sildenafil potentiates the hypotensive effect of concurrently administered nitrates, therefore patients receiving nitrate therapy should be advised to use an alternate treatment for erectile dysfunction.

Some patients receiving sildenafil may experience a transient visual disturbance which makes objects appear to have a blue tint or hue. While the efficacy of sildenafil in treating erectile dysfunction is associated with its competitive inhibition of phosphodiesterase type 5 causing the release of nitric oxide in the blood vessels of the corpus cavernosum, higher doses may cause a transient inhibition of phosphodiesterase 6 located in the retina, resulting in altered blue/green color discrimination.

Sildenafil is metabolized in the liver by the cytochrome P450 enzyme system, therefore, drugs which are inhibitors or inducers of this system should be expected to alter levels of sildenafil when given concomitantly.

Caution should be exercised when prescribing sildenafil to patients with underlying cardiovascular disease.

See also...