Dosing and uses of Revatio, Viagra (sildenafil)
Adult dosage forms and strengths
tablet (Revatio)
- 20mg
tablet (Viagra)
- 25mg
- 50mg
- 100mg
injectable solution (Revatio)
- 10mg/12.5mL
oral suspension (Revatio)
- 10mg/mL (when reconstituted)
Erectile Dysfunction
Viagra
50 mg PO 1 hour before sexual activity; may be increased to 100 mg or reduced to 25 mg, depending on effectiveness and tolerance; not to exceed 100 mg/day
Pulmonary Arterial Hypertension
Revatio
PO: 5 mg or 20 mg 3 times daily, administered 4-6 hours apart
IV: 2.5-mg or 10-mg bolus 3 times daily if patient is temporarily unable to take PO
Recommended PO/IV dose not to be exceeded
Adding Revatio to bosentan does not have any beneficial effect on exercise capacity
Dosing Modifications
Heaptic impairment or severe renal impairment: Use initial dose of 25 mg
Geriatric Dosing
Erectile Dysfunction
- Viagra
- >65 years: 25 mg PO initially 1 hour before sexual activity
Pulmonary Arterial Hypertension
- Revatio
- PO: 5 mg or 20 mg 3 times daily, administered 4-6 hours apart
- IV: 2.5-mg or 10-mg bolus 3 times daily if patient is temporarily unable to take PO
- Recommended PO/IV dose not to be exceeded
- Adding Revatio to bosentan does not have any beneficial effect on exercise capacity
- Clinical trials found no significant difference in response between elderly patients and younger adults; however, cautious dose selection should be considered in elderly because of greater frequency of decreased hepatic, renal, and cardiac function, as well as comorbid conditions and concomitant pharmacotherapy
- Compared with healthy younger volunteers, healthy elderly volunteers (≥65 years) had reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma concentrations of sildenafil and its active N-desmethyl metabolite, respectively
Pediatric dosage forms and strengths
Not to be prescribed to children (1-17 years) for pulmonary arterial hypertension (PAH); this recommendation against use is based on long-term clinical pediatric trial showing that children taking high doses had higher risk of death than children taking low doses and that low doses were not effective in improving exercise ability (see Cautions)
Revatio, Viagra (sildenafil) adverse (side) effects
>10%
Headache (7-16%)
1-10%
Flushing (4-10%)
Epistaxis (8%)
Dyspepsia (4-8%)
Insomnia (6%)
Erythema (5%)
Diarrhea (4%)
Dizziness (2%)
Skin rash (2%)
Postmarketing Reports
Vaso-occlusive crisis (PAH secondary to sickle-cell anemia)
Warnings
Contraindications
Hypersensitivity
Soluble guanylate cyclase (sGC) stimulators (eg, riociguat); concomitant use can cause hypotension
Coadministration with nitrates
- Coadministration with nitrates (either regularly and/or intermittently) and nitric oxide donors
- Consistent with the effects of PDE5 inhibition on the nitric oxide/cyclic guanosine monophosphate pathway, PDE5 inhibitors may potentiate the hypotensive effects of nitrates
- A suitable time interval following PDE5 dosing for the safe administration of nitrates or nitric oxide donors has not been determined
Cautions
Elicits vasodilatory properties, resulting in mild and transient decreases in blood pressure
Use with caution in patients with anatomic deformation of penis (eg, angulation, cavernosal fibrosis, or Peyronie disease), conditions potentially predisposing to priapism (eg, sickle cell anemia, multiple myeloma, or leukemia), cardiovascular disease, bleeding disorders, active peptic ulcer disease, liver disease, renal impairment, multidrug antihypertensive regimens, retinitis pigmentosa, concomitant use of CYP3A4 inhibitors
Pulmonary vasodilators may significantly worsen cardiovascular status of patients with pulmonary veno-occlusive disease
Patient taking alpha blocker should be stabilized before starting phosphodiesterase (PDE)-5 inhibitor, which should be initiated at lowest dose; if patient is already taking optimized dose of PDE-5 inhibitor, alpha blocker should be initated at lowest dose to avoid hypotension
Not to be taken with other PDE-5 inhibitors
Sudden decrease or loss of hearing, which may be accompanied by tinnitus and dizziness
Viagra: Patients should stop sildenafil and seek medical care if a sudden loss of vision occurs in 1 or both eyes, which could be a sign of nonarteritic anterior ischemic optic neuropathy (NAION); use with caution, and only when the anticipated benefits outweigh the risks, in patients with a history of NAION; patients with a ”crowded” optic disc may also be at an increased risk of NAIOn
Viagra: Potential for cardiac risk with sexual activity in patients with preexisting cardiovascular disease; therefore, treatment for erectile dysfunction generally should not be instituted in men for whom sexual activity is inadvisable because of their underlying cardiovascular status
May cause dose-related impairment of color discrimination; use caution in patients with retinitis pigmentosa
Evaluate underlying causes of erectile dysfunction or BPH before initiating therapy
Revatio: In small, prematurely terminated study of patients with PAH secondary to sickle-cell disease, vaso-occlusive crises requiring hospitalization were more commonly reported by patients who received sildenafil than by those randomized to placebo; effectiveness of sildenafil in PAH secondary to sickle-cell anemia has not been established; the clinical relevance to men treated for erectile dysfunction with sildenafil is not known
Revatio: Not for use in children with PAH; increased mortality with increasing doses (hazard ratio 3.5) was observed in randomized, double-blind, placebo-controlled clinical trial of 234 children (1-17 years) with PAH who had mild-to-moderate symptoms at baseline
Revatio: Epistaxis occurred in 13% of patients with PAH secondary to connective tissue disease (eg, scleroderma); this effect was not seen in idiopathic PAH; incidence was also higher in those receiving concomitant PO vitamin K antagonist therapy (9%) than in those not receiving such therapy (2%)
Pregnancy and lactation
Pregnancy category: B
Lactation: Unknown whether drug is distributed into breast milk
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Revatio, Viagra (sildenafil)
Mechanism of action
Inhibits PDE-5, increasing cyclic guanosine monophosphate cGMP to allow smooth-muscle relaxation
Absorption
Bioavailability: 40%
Peak plasma time: 30-120 min
Metabolism
Metabolized in liver by CYP3A4 and (in minor amounts) CYP2C9
Metabolites: N-desmethyl metabolite (active; possesses 50% of sildenafil's PDE-5-inhibiting activity)
Elimination
Half-life: Parent drug, 3-4 hr; active metabolite, 10-70 min
Excretion: Feces (80%), urine (13%)
Administration
IV Administration
Revatio: Administer as an IV bolus
Oral Administration
Viagra
- May take with or without food
- Take as needed, about 1 hr before sexual activity; however, may be taken anywhere from 30 minutes to 4 hr before sexual activity
- The maximum recommended dosing frequency is once daily
Revatio
- Tablets or oral suspension: Administer doses 4-6 hr apart
Storage
Revatio tablets or IV solution
- Store at controlled room temperature 20-25°C (68-77°F)
- Excursions permitted to 15-30°C (59-86°F)
Revatio reconstituted oral suspension
- Store <30°C (86°F) or in a refrigerator between 2-8°C (36-46°F)
- Do not freeze
- Discard unused oral suspension after 60 days
