section name header

Pronunciation

var-DEN-a-fil

Classifications

Therapeutic Classification: erectile dysfunction agents

Pharmacologic Classification: phosphodiesterase type 5 inhibitors

Indications

REMS


Action

  • Increases cyclic guanosine monophosphate (cGMP) levels by inhibiting phosphodiesterase type 5, an enzyme responsible for the breakdown of cGMP. cGMP produces smooth muscle relaxation of the corpus cavernosum, which in turn promotes increased blood flow and subsequent erection.
Therapeutic effects:
  • Enhanced blood flow to the corpus cavernosum and erection sufficient to allow sexual intercourse.
  • Requires sexual stimulation.

Pharmacokinetics

Absorption: 15% absorbed following oral administration; absorption is rapid.

Distribution: Extensive tissue distribution; penetrates semen.

Protein Binding: 95%.

Metabolism/Excretion: Mostly metabolized by the liver via the CYP3A4 isoenzyme and to a lesser extent by the CYP2C isoenzyme. M1 metabolite has anti-erectile dysfunction activity. Parent drug and metabolites are mostly excreted in feces. 2–6% renally eliminated.

Half-Life: 4–6 hr.

Time/Action Profile

ROUTEONSETPEAKDURATION
POrapid0.5–2 hr4 hr





Contraind./Precautions

Contraindicated in:

Use Cautiously in:

Adv. Reactions/Side Effects

Derm: flushing

EENT: HEARING LOSS, rhinitis, sinusitis, VISION LOSS

GI: dyspepsia, nausea

GU: priapism

Neuro: headache, amnesia, dizziness

Misc: flu syndrome

Interactions

Drug-drug:

Route/Dosage

Tablets

Orally Disintegrating Tablets

Hepatic Impairment

Availability

(Generic available)

Assessment

Implementation

Patient/Family Teaching

Evaluation/Desired Outcomes

Canadian Brand Names

Levitra, Staxyn