CIALIS

Expert Opin Pharmacother. 2005 Jan;6(1):75-84.
Comparison of clinical trials with sildenafil, vardenafil and tadalafil in erectile dysfunction.
Doggrell SA.
Doggrell Biomedical Communications, 47 Caronia Crescent, Lynfield, Auckland, New Zealand.

Erectile dysfunction (ED) affects up to 50% of men, between 40 and 70years of age. In the first major trial of sildenafil in ED, at 24weeks, improved erections were reported by 77 and 84% of men taking sildenafil 50 and 100mg, respectively. Subsequently, sildenafil has been reported to be effective in men with ED associated with diabetes and prostate cancer, and in psychogenic ED. Sildenafil is safe in men with coronary artery disease, provided it is not used with the nitrates (a contraindication). The most commonly reported adverse effects with sildenafil are headache, flushing and dyspepsia. Vardena-fil is more potent and more selective than sildenafil at inhibiting phosphodiesterase-5. Vardenafil is similarly effective to sildenafil in the treatment of ED. The only advantage that vardenafil has over sildenafil is that it does not inhibit phosphodiesterase-6 to alter colour perception, a rare side effect which sometimes occurs with sildenafil. Tadalafil has a longer duration of action than sildenafil and vardenafil. Tadalafil is similarly effective as sildena-fil in the treatment of ED. In comparison studies, tadalafil is preferred to sildenafil (50/100mg) by men with ED, possibly because of its longer duration of action. Of the phosphodiesterase inhibitors, tadalafil may displace sild-enafil as the drug of choice among men with ED.

Stroke. 2005 Mar;36(3):557-60. Epub 2005 Feb 03.
Effects of high altitude exposure on cerebral hemodynamics in normal subjects.
Van Osta A, Moraine JJ, Melot C, Mairbaurl H, Maggiorini M, Naeije R.
Laboratory of Physiology, Faculty of Medicine, Free University of Brussels, Belgium.

BACKGROUND AND PURPOSE: Acute mountain sickness (AMS) may be an early stage of high altitude cerebral edema. If so, AMS could result from an alteration of dynamic autoregulation of cerebral blood flow resulting in overperfusion of capillaries and vasogenic cerebral edema. METHODS: We measured middle cerebral artery blood flow velocity (Vmca) by transcranial Doppler and arterial blood pressure by finger plethysmography at 490 m and 20 hours after arrival at 4559 m in 35 volunteers who had been randomized to tadalafil, dexamethasone, or placebo in a study on the pharmacological prevention of high altitude pulmonary edema. A dynamic cerebral autoregulation index (ARI) was calculated from continuous recordings of Vmca and blood pressure during transiently induced hypotension. RESULTS: Altitude was associated with an increase in a cerebral-sensible AMS (AMS-C) score (P<0.001) and with a decrease in arterial oxygen saturation (Sao2), whereas average Vmca or ARI did not change. However, at altitude, the subjects with the lowest ARI combined with the lowest Sao2 presented with the highest AMS-C score (P<0.03). In addition, a stepwise multiple linear regression analysis on arterial Pco2, Sao2, and baseline or altitude ARI identified altitude ARI as the only significant predictor of the AMS-C score (P=0.01). The AMS-C score was lower in dexamethasone-treated subjects compared with high altitude pulmonary edema-susceptible untreated subjects. Neither tadalafil nor dexamethasone had any significant effect on Vmca or ARI. CONCLUSIONS: High altitude hypoxia is associated with impairment in the regulation of the cerebral circulation that might play a role in AMS pathogenesis.

GENERIC NAME: tadalafil
BRAND NAME: Cialis

DRUG CLASS AND MECHANISM: Tadalafil is an oral drug that is used to treat impotence (the inability to attain or maintain a penile erection.). It is a phosphodiesterase inhibitor that is similar to sildenafil (Viagra) and vardenafil (Levitra).

Penile erection is caused by the engorgement of the penis with blood. This engorgement occurs when the blood vessels delivering blood to the penis increase in size and increase the delivery of blood to the penis. At the same time, the blood vessels carrying blood away from the penis decrease in size and decrease the removal of blood from the penis. Sexual stimulation that leads to the engorgement and erection causes the production and release of nitric oxide in the penis. Nitric oxide then activates the enzyme, guanylate cyclase to produce cyclic guanosine monophosphate (cGMP). The cGMP is primarily responsible for increasing and decreasing the size of the blood vessels carrying blood to and from the penis, respectively. Tadalafil prevents an enzyme called phosphodiesterase-5 from destroying cGMP so that cGMP persists longer. The longer cGMP persists, the more prolonged the engorgement of the penis. Tadalafil was approved by the FDA in November, 2003.

PREPARATIONS: Tablets: 5, 10, and 20 mg.

STORAGE: Store at room temperature between 15-30°C (59-86°F).

PRESCRIBED FOR: Tadalafil is used for the treatment of impotence.

DOSING: For most individuals, the recommended starting dose of tadalafil is 10 mg per day taken before sexual activity. Depending on the adequacy of the response or side effects, the dose may be increased to 20 mg or decreased to 5 mg a day. The effect of tadalafil may last up to 36 hours. Individuals who are taking medications that increase the blood levels of tadalafil should not exceed 10 mg in 72 hours (See drug interactions.)

DRUG INTERACTIONS: The breakdown and elimination of tadalafil from the body may be decreased by erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), indinavir (Crixivan) and ritonavir (Norvir). Therefore, these drugs may increase the concentration of tadalafil in the blood. If these drugs are being used at the same time as tadalafil, the dose of tadalafil should be reduced in order to avoid side effects from high levels of tadalafil. Tadalafil increases the heart rate and also exaggerates the blood pressure lowering effects of nitrates (e.g., nitroglycerin). In patients who take nitrates for chest pain (angina), tadalafil could cause chest pain by increasing heart rate and lowering blood pressure. Therefore, patients with angina should not use tadalafil. Tadalafil also exaggerates the blood pressure lowering effects of some alpha-blocking drugs e.g., terazosin (Hytrin). Individuals who take these alpha-blockers should not use tadalafil.

PREGNANCY: Tadalafil is not approved for use in pregnant women.

NURSING MOTHERS: Tadalafil has not been evaluated in women who are breastfeeding.

SIDE EFFECTS: The most common side effects of tadalafil are facial flushing (reddening), headaches, stomach upset, diarrhea, flu-like symptoms and nausea. Tadalafil also may cause chest pain, low blood pressure, blurred vision and changes in color vision, abnormal ejaculation and priapism (prolonged and painful erection).

Caution! Before starting to take this medicine, it is vital that you should consult your doctor! Do not use it on your own initiative, without medical advice.