Vardenafil, also known under the brand name Levitra, is used to treat erectile dysfunction. While the initial vardenafil dosage typically recommended is 10 mg, taken one hour before sexual activity, a number of factors can raise or lower that dose. Variables like the age, medical conditions, and other medications of the patient may require that the dose be reduced, as may the incidence of disagreeable side-effects. If the effects of a low initial varedenafil dosage are unsatisfactory, the dosage may need to adjusted upward. According to the manufacturer of vardenafil, dosage frequency should be no more than one per day.
Vardenafil is extremely similar in both its activity and chemical structure to sildenafil citrate, the drug sold under the brand name Viagra®. Both vardenafil and sildenafil citrate are members of a class of drug known as phosphodiesterase type 5 (PDE5) inhibitors. The risks of vardenafil are much the same as those of other drugs in this family, including side-effects like nausea and, infrequently, photosensitivity, back pain, abdominal pain, blurry vision, facial edema, eye pain, racing heart, low blood pressure, rash, itch, muscle and joint pain or a painful erection lasting more than four hours. Serious, but rare side-effects include sudden deafness or heart attack. Since a higher vardenafil dosage may increase the incidence and seriousness of these side-effects, it is preferable to use a low dose when beginning a course of treatment.
Patients taking other medications should discuss possible drug interactions with their doctor before taking vardenafil, as many interactions have the potential to be serious or fatal. Drug interactions between nitrates and the drug can result in a potentially fatal drop in blood pressure. The alpha blockers alfuzosin, doxazosin, prazosin, tamsulosin and terazosin, sometimes used in the treatment of high blood pressure or benign prostatic hyperplasia, have also been observed to exacerbate the blood pressure, lowering effects of vardenafil. A number of prescription anti-fungal medications may increase the level of the medication in the bloodstream, making it necessary to adjust the vardenafil dosage downward. If the patient is taking the heart arrhythmia medications quinidine, procainamide, amiodarone or sotalol, other treatments for erectile dysfunction should be used, as the combination of these drugs with vardenafil may result in an extremely dangerous heart condition known as QT prolongation.
If administering vardenafil to a patient who is taking medications that affect the liver enzyme cytochrome P450, it may be necessary to adjust the dose to compensate. Due to the role of this liver enzyme in the metabolism of the drug, a lower initial vardenafil dosage should be used in patients with diminished liver function. In many of these patients, an initial dose as low as 2.5 mg may be sufficient.