TYPICAL USAGE: Erectile dysfunction.
SIDE EFFECTS: Nausea, stomach upset, skin rash, acute toxicity.
DRUG INTERACTION: The breakdown and elimination of Tazzle 10mg 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 Tazzle 10mg.
MECHANISM OF ACTION: Tazzle 10mg is an oral drug that is used for treating impotence (the inability to attain or maintain a penile erection) andbenign prostatic hyperplasia (BPH). It is in a class of drugs called phosphodiesterase inhibitors that also includes sildenafil (Viagra) andvardenafil (Levitra). Erection of the penis is caused by the filling of the penis with blood. Filling occurs because the blood vessels that bring blood to the penis increase in size and deliver more blood to the penis, and, at the same time, the blood vessels that take blood away from the penis decrease in size and remove less blood from the penis. Sexual stimulation that leads to an erection causes the production and release of nitric oxide in the penis. The nitric oxide causes an enzyme, guanylate cyclase, to produce cyclic guanosine monophosphate (cGMP). It is cGMP that is primarily responsible for increasing and decreasing the size of blood vessels carrying blood to and from the penis, respectively, and causing an erection. When the cGMP is destroyed by another enzyme, phosphodiesterase-5, the blood vessels return to their normal size, blood leaves the penis, and the erection ends. Tazzle 10mg prevents phosphodiesterase-5 from destroying cGMP so that cGMP stays around longer. The persistence of cGMP leads to a more prolonged engorgement of the penis with blood.The mechanism whereby tadalafil improves the symtoms of BPH is not clear, but phosphodiesterase-5 also is present in the muscles of the bladder and the prostate, and it has been suggested that the relaxation of these muscles may make the passage of urine less difficult, for example, by reducing the pressure in the muscle surrounding the opening to the urethra that controls the flow of urine from the bladder. Tazzle 10mg was approved by the FDA in November 2003.