Vardenafil

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Vardenafil (Brand names: Levitra, Vivanza) is a medecine taken by mouth for the treatment of erectile dysfunction (ED). ED is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection.

Vardenafil works only with sexual stimulation and does not increase sexual desire. Vardenafil allows an erection to last long enough to have a satisfactorily complete sexual activity.

Contents

[edit] BRAND NAMES

[edit] STRUCTURE

Vardenafil.jpg

[edit] MECHANISM OF ACTION

The physiological mechanism responsible for erection of the penis involves the release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. Nitric oxide then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood.

Phosphodiesterase type 5 (PDE5) is the enzyme responsible for degradation of cGMP

Vardenafil, is an inhibitor of phosphodiesterase type 5 (PDE5). When sexual stimulation causes local release of NO, inhibition of PDE5 by Vardenafil causes increased levels of cGMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum. Vardenafil at recommended doses has no effect in the absence of sexual stimulation.

Vardenafil is rapidly absorbed (Tmax approximately 40 min) and acts in about 30 min and the effects last for about 5 hours; it has a short plasma half-life of approximately 4 hours.

[edit] INDICATIONS

  • Vardenafil is indicated in adult men with erectile dysfunction, which is the inability to achieve or maintain a penile erection sufficient for satisfactory sexual performance.

[edit] DOSAGE

The starting dose of Vardenafil is 10 mg taken as needed about 30-60 minutes before sexual activity. The dose may be increased to a maximum of 20 mg or decreased to 5 mg depending on the effectiveness and side effects.

Patients with liver problems and patients ≥ 65 years of age should start treatment with the 5 mg dose.

The maximum recommended dosing frequency is one tablet per day.

[edit] CONTRAINDICATIONS

  • Vardenafil potentiate the hypotensive effects of nitrates and its administration in patients who use nitric oxide donors or nitrates (often used to control chest pain, also known as angina) in any form is therefore contraindicated.
  • Patients who have loss of vision in one eye because of non-arteritic anterior ischaemic optic neuropathy (NAION)
  • In men for whom sexual activity is inadvisable (e.g.Patients with severe cardiovascular disorders such as unstable angina or severe cardiac failure)
  • Severe hepatic impairment
  • Hypotension (blood pressure <90/50 mmHg),
  • Recent history of stroke or myocardial infarction

[edit] PRECAUTIONS

  • Vardenafil has systemic vasodilatory properties and may augment the blood pressure lowering effect of anti-hypertensive medications.
  • Seek emergency treatment for prolonged erections greater than 4 hours and priapism
  • Patients should seek medical attention and stop taking Vardenafil in case of sudden loss of vision in one or both eyes ( increased risk of non-arteritic anterior ischemic optic neuropathy)
  • Patients should seek medical attention and stop taking Vardenafil in case of sudden decrease or loss in hearing
  • Patients with congenital QT syndrome or taking antiarrhythmics class IA or antiarrhythmics class III, should avoid using Vardenafil

[edit] INTERACTIONS

  • CYP3A4 inhibitors: For concomitant use with potent CYP3A4 inhibitors (e.g. Ritonavir, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, saquinavir, ketoconazole, telithromycin), dose adjustment may be needed. (Potent CYP3A4 inhibitors increase Vardenafil plasma levels)
  • Alpha-blockers: Caution is advised when Phosphodiesterase Type 5 (PDE5) inhibitors are co-administered with alpha-blockers e.g. Hytrin® (terazosin HCl), Flomax® (tamsulosin HCl), Cardura® (doxazosin mesylate), Minipress® (prazosin HCl) or Uroxatral® (alfuzosin HCl). Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. In some patients, concomitant use of these two drug classes can lower blood pressure significantly leading to symptomatic hypotension. Patients should be stable on alpha-blocker therapy prior to initiating and should initiate Vardenafil with 5 mg daily dosage.
  • Vardenafil may augment the blood pressure lowering effect of anti-hypertensive medications.

[edit] PREGNANCY AND LACTATION

Pregnancy Category B (US). Vardenafil is not indicated for use in women.

[edit] SIDE EFFECTS

Most common adverse reactions reported ( ≥ 2% of patients) are headache, flushing, nasal congestion, dyspepsia, sinusitis, flu syndrome, dizziness, increased creatine kinase, nausea and back pain.

[edit] RELATED LINKS

Patient Information about LEVITRA
Erectile Dysfunction (ED) - Causes, symptoms and treatment

[edit] BIBLIOGRAPHY

[edit] REFERENCES

Sexual dysfunction pharmacotherapies
PDE5 inhibitors Avanafil   Sildenafil   Tadalafil   Vardenafil
Prostaglandins (Erectile dysfunction) Alprostadil
Premature ejaculation Dapoxetine