Sildenafil, sold under the brand name Viagra, among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. It is unclear if it is effective for treating sexual dysfunction in women. It is taken by mouth or by injection into a vein. Onset is typically within twenty minutes and lasts for about two hours.
Nitric oxide is a colorless gas with the formula NO. It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula. Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding.
A phosphodiesterase (PDE) is an enzyme that breaks a phosphodiester bond. Usually, phosphodiesterase refers to cyclic nucleotide phosphodiesterases, which have great clinical significance and are described below. However, there are many other families of phosphodiesterases, including phospholipases C and D, autotaxin, sphingomyelin phosphodiesterase, DNases, RNases, and restriction endonucleases, as well as numerous less-well-characterized small-molecule phosphodiesterases.
Tadalafil, sold under the brand name Cialis among others, is a medication used to treat erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension. It is taken by mouth. Onset is typically within half an hour and the duration is up to 36 hours.
Cyclic guanosine monophosphate (cGMP) is a cyclic nucleotide derived from guanosine triphosphate (GTP). cGMP acts as a second messenger much like cyclic AMP. Its most likely mechanism of action is activation of intracellular protein kinases in response to the binding of membrane-impermeable peptide hormones to the external cell surface.
Vardenafil is a PDE5 inhibitor used for treating erectile dysfunction that is sold under the brand name Levitra among others.
Yohimbine, also known as quebrachine, is an indole alkaloid derived from the bark of the African tree Pausinystalia johimbe; also from the bark of the unrelated South American tree Aspidosperma quebracho-blanco. Yohimbine is an α2-adrenergic receptor antagonist, and has been used in a variety of research projects. It is a veterinary drug used to reverse sedation in dogs and deer.
Tetrahydrobiopterin (BH4, THB), also known as sapropterin (INN), is a cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and is a cofactor for the production of nitric oxide (NO) by the nitric oxide synthases. Chemically, its structure is that of a (dihydropteridine reductase) reduced pteridine derivative (quinonoid dihydrobiopterin).
A phosphodiesterase type 5 inhibitor is a vasodilating drug that works by blocking the degradative action of cGMP-specific phosphodiesterase type 5 (PDE5) on cyclic GMP in the smooth muscle cells lining the blood vessels supplying various tissues. These drugs dilate the corpora cavernosa of the penis, facilitating erection with sexual stimulation, and are used in the treatment of erectile dysfunction (ED). Sildenafil was the first effective oral treatment available for ED. Because PDE5 is also present in the smooth muscle of the walls of the arterioles within the lungs, two PDE5 inhibitors, sildenafil and tadalafil, are FDA-approved for the treatment of pulmonary hypertension. As of 2019, the wider cardiovascular benefits of PDE5 inhibitors are being appreciated.
Cyclic guanosine monophosphate-specific phosphodiesterase type 5 is an enzyme from the phosphodiesterase class. It is found in various tissues, most prominently the corpus cavernosum and the retina. It has also been recently discovered to play a vital role in the cardiovascular system.
Avanafil is a PDE5 inhibitor approved for erectile dysfunction by the FDA on April 27, 2012 and by EMA on June 21, 2013. Avanafil is sold under the brand names Stendra and Spedra. It was invented at Mitsubishi Tanabe Pharma, formerly known as Tanabe Seiyaku Co., and licensed to Vivus Inc., which partnered with Menarini Group to commercialise Spedra in over forty European countries, Australia, and New Zealand. Metuchen Pharmaceuticals obtained exclusive rights within the United States.
Herbal viagra is a name that can be given to any herbal product advertised as treating erectile dysfunction. There are many different products advertised as herbal viagra, but with varying ingredients. There are no clinical trials or scientific studies that support the effectiveness of any of these ingredients for the treatment of erectile dysfunction and some products have been found to contain drugs and other adulterants, and have been the subject of FDA and FTC warnings and actions to remove them from the market.
Acetildenafil (hongdenafil) is a synthetic drug which acts as a phosphodiesterase inhibitor. It is an analog of sildenafil (Viagra) which has been detected in numerous different brands of supposedly "herbal" aphrodisiac products sold to boost libido and alleviate erectile dysfunction.
A nitrovasodilator is a pharmaceutical agent that causes vasodilation by donation of nitric oxide (NO), and is mostly used for the treatment and prevention of angina pectoris.
Nitric oxide is a molecule and chemical compound with chemical formula of NO. In mammals including humans, nitric oxide is a signaling molecule involved in several physiological and pathological processes. It is a powerful vasodilator with a half-life of a few seconds in the blood. Standard pharmaceuticals such as nitroglycerine and amyl nitrite are precursors to nitric oxide. Low levels of nitric oxide production are typically due to ischemic damage in the liver.
Sulfoaildenafil (thioaildenafil) is a synthetic drug that is a structural analog of sildenafil (Viagra). It was first reported in 2005, and it is not approved by any health regulation agency. Like sildenafil, sulfoaildenafil is a phosphodiesterase type 5 inhibitor.
Aildenafil (methisosildenafil) is a synthetic drug that is a structural analog of sildenafil (Viagra). It was first reported in 2003, and it is not approved by any health regulation agency. Like sildenafil, aildenafil is a phosphodiesterase type 5 inhibitor.
Phosphodiesterases (PDEs) are a superfamily of enzymes. This superfamily is further classified into 11 families, PDE1 - PDE11, on the basis of regulatory properties, amino acid sequences, substrate specificities, pharmacological properties and tissue distribution. Their function is to degrade intracellular second messengers such as cyclic adenine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) which leads to several biological processes like effect on intracellular calcium level by the Ca2+ pathway.
Homosildenafil is a synthetic drug which acts as a phosphodiesterase inhibitor. It is an analog of sildenafil and vardenafil. Homosildenafil was first identified as an adulterant in sex enhancement products in 2003 and was more recently detected in dietary supplements.
Desmethylsibutramine (BTS-54354) is an active metabolite of the anorectic drug sibutramine. It is a more potent monoamine reuptake inhibitor than sibutramine and has been sold as an ingredient in weight loss products sold as dietary supplements, along with related compounds such as the N-ethyl and 3,4-dichloro derivatives.
