This condition may require prompt medical treatment to prevent serious and permanent damage to your penis. Sildenafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. Just take it half an hour before you a go mash a work have sex and you good. By controlling the enzyme, sildenafil helps to maintain an erection after the penis is stroked. In some patients, the use of VIAGRA with alpha-blockers can lead to a drop in blood pressure or to fainting medicines called HIV protease inhibitors, such as ritonavir Norvir , indinavir sulfate Crixivan , saquinavir Fortovase or Invirase , or atazanavir sulfate Reyataz some types of oral antifungal medicines, such as ketoconazole Nizoral and itraconazole Sporanox some types of antibiotics, such as clarithromycin Biaxin , telithromycin Ketek , or erythromycin other medicines that treat high blood pressure other medicines or treatments for ED VIAGRA contains sildenafil, which is the same medicine found in another drug called REVATIO. Who may not be able to take sildenafil Sildenafil is not suitable for some people.Viagra, trade name of the first oral drug for male impotence, introduced by the pharmaceutical company Pfizer, Inc., in Also known by the chemical name sildenafil citrate, it is one of a category of drugs known as phosphodiesterase-5 inhibitors. See also PDE Keep in mind that all the meds that can be found in the drug stores abroad are not necessarily going to be available in Jamaica. I have gone to pick up prescriptions on . Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is mg. Don’t take sildenafil (Viagra) more than once daily (at any dose). Written by Brian Leonard, PharmD, BCACP, BCGP.