Cialis DRUG CLASS AND MECHANISM: Tadalafil is an effective oral drug used to treat impotence (the inability to achieve or maintain an erection) and benign prostatic hyperplasia (BPH). It is included in a class of drugs called phosphodiesterase inhibitors that also includes sildenafil (Viagra) and vardenafil (Levitra. Errection depends on the blood rate of blood circulation in the blood vessels in the penis. It happens with the increase in size the blood vessels which bring blood towards the penis and decrease the blood vessels which carry blood away from the penis. Sexual arousal leading to an erection causes the production and release of nitric oxide in the penis. Nitric oxide in the penis causes the enzyme guanylate cyclase to produce cyclic guanosine monophosphate (cGMP). The cGMP is basic element which is responsible for the increasing and decreasing the size of the blood vessels that carry blood to and away from the penis, respectively, causing an erection. When another enzyme, phosphodiesterase-5 destroys cGMP, the blood vessels return to their original size and the blood leaves the penis and an erection ends. Tadalafil saves the cGMP from destroying by phosphodiesterase-5 to make its stay longer. The longer stay of cGMP leads to a longer lasting bump of the penis with blood. The mechanism of improvement of BPH symptoms by tadalafil is not understandable, but phosphodiesterase-5 is also present in the muscles of bladder and the prostate and relaxation of these muscles is supposed to make the passage of urine easy. Tadalafil characteristics and effects: Tadalafil was approved by FDA in November 2003. Tablets: 2.5, 5, 10 and 20mg Storage: Tadalafil should be stored at room temperature 15-30 c (59-86 F). Proper Dose Generally, the most recommended starting dose is 10mg /day and it’s taken before the sexual activity. Keeping yourself in safe limit about the side effects and response, the dose may be increased to 20 mg or decreased to 5mg/day. The effect of tadafil may last up to 36 hours. The individuals who are taking medications for increasing their blood levels; they should not exceed the 10mg dose of tadalafil in 72 hours. For the daily use without regard to sexual activity, it’s recommended to use 2.5-5mg, but for BPH, or BPH and ED, the recommended dose is 5mg/day. The food does not affect the intestinal absorption, so it can be taken with or without food. DRUG INTERACTIONS: The use of erythromycin, ketoconazole, itraconazole (sporanox etc, may make the body reduce the break down and elimination of tadalafil and these medicines consequently increase the levels of tadalafil in the blood. If these drugs are used at the same time, side effects of high level dose of tadalafil can be avoided. 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 levels 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. Increases in heart rate by tadalafil and lowering of blood pressure is caused by the nitrates like nitroglycerin, isosorbide dinitrate (isordil), isosorbide monnitrate (Imdur, Ismo, Monoket), nitroglycerin (Nitro-Dur, Transderm-Nitro) that are used primarily for treating heart pain (angina). The use of nitrates by the heart patients along with tadalafil may prove fatal and even it may lead to severe heart attack. Therefore the nitrates and tadalafil should never be used at the same time.