Avanafil is a PDE5 inhibitor approved for erectile dysfunction by FDA and by EMA. Avanafil is known by the trademark names Stendra and Spedra and was developed by Vivus Inc. Avanafil selectively inhibits PDE5, thus inhibiting the degradation of cyclic guanosine monophosphate (cGMP) found in the smooth muscle of the corpus cavernosa of the penis. The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which results in increased levels of cGMP, producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Avanafil has no direct relaxant effect on isolated human corpus cavernosum, but enhances the effect of NO by inhibiting PDE5, which is responsible for degradation of cGMP in the corpus cavernosum. Because sexual stimulation is required to initiate the local release of nitric oxide, the inhibition of PDE5 has noeffect in the absence of sexual stimulation. The advantage of avanafil is that it has very fast onset of action compared with other PDE5 inhibitors. It is absorbed quickly, reaching a maximum concentration in about 30–45 minutes. About two-thirds of the participants were able to engage in sexual activity within 15 minutes.

Mirabegron (trade name Myrbetriq in the US and Betmiga in Europe) is a drug for the treatment of overactive bladder (OAB). It was developed by Astellas Pharma and was approved in the United States in July 2012. Originally developed as a treatment for diabetes, the development of mirabegron was later refocused to OAB. Mirabegron is an orally bioavailable agonist of the human beta-3 adrenergic receptor (ADRB3), with muscle relaxing, neuroprotective and potential antineoplastic activities. Upon oral administration, mirabegron binds to and activates ADRB3, which leads to smooth muscle relaxation. Mirabegron also restores sympathetic stimulation in mesenchymal stem cell (MSC) niches, inhibits JAK2-mutated hematopoietic stem cell (HSC) expansion and blocks the progression of myeloproliferative neoplasms (MPNs). Lack of sympathetic stimulation of the MSC and HSC niche is associated with the development of MPNs.

Fesoterodine (trade name Toviaz) is a prodrug of 5-hydroxymethyl tolterodine, which is also the active metabolite of tolterodine. Fesoterodine and its active metabolites are nonsubtype selective, competitive antagonists of human muscarinic receptors, but 5-hydroxymethyl tolterodine has greater potency than the parent compound. A prodrug approach was necessary for systemic bioavailability of 5-hydroxymethyl tolterodine after oral administration. Fesoterodine was originated by Schwarz Pharma (later a subsidiary of UCB) and is being developed by Pfizer for the treatment of overactive bladder and urinary urge incontinence. The agent is launched in several countries for the treatment of overactive bladder, including the US, Japan, Canada, Europe and Asia.

Silodosin is a selective antagonsit of alpha-1a adrenergic receptor which was developed by Kissei Pharmaceutical. The drug was approved by FDA under the name Rapaflo for the treatment of signs and symptoms associated with benign prostatic hyperplasia.

Darifenacin is a selective muscarinic receptor M3 antagonist which was approved by FDA for the treatment of overactive bladder.

Trospium is an antispasmodic, antimuscarinic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. Receptor assays showed that trospium has negligible affinity for nicotinic receptors as compared to muscarinic receptors at concentrations obtained from therapeutic doses. Trospium antagonizes the effect of acetylcholine on muscarinic receptors in cholinergically innervated organs. Its parasympatholytic action reduces the tonus of smooth muscle in the bladder. Trospium is marketed under the brand name Sancturain the US, Tropez OD in India,Trosec in Canada, Regurin and Flotros in the United Kingdom and Spasmex in Germany, Russia, Turkey, Argentina, Chile and Israel.

Solifenacin is a competitive muscarinic acetylcholine receptor antagonist. The binding of acetylcholine to these receptors, particularly the M3 receptor subtype, plays a critical role in the contraction of smooth muscle. By preventing the binding of acetylcholine to these receptors, solifenacin reduces smooth muscle tone in the bladder, allowing the bladder to retain larger volumes of urine. It is FDA approved for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. Common adverse reactions include constipation, Xerostomia. Inhibitors of CYP3A4 may increase the concentration of Solifenacin. Vice versa, CYP3A4 Inducers decrease concentration.

Alfuzosin is a quinazoline-derivative alpha-adrenergic blocking agent used to treat hypertension and benign prostatic hyperplasia. Alfuzosin is marketed in the United States by Sanofi Aventis under the brand name Uroxatral. UROXATRAL (alfuzosin HCl extended-release tablets) is indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia. UROXATRAL is not indicated for the treatment of hypertension. Alfuzosin is a non-subtype specific alpha(1)-adrenergic blocking agent that exhibits selectivity for alpha(1)-adrenergic receptors in the lower urinary tract. Inhibition of these adrenoreceptors leads to the relaxation of smooth muscle in the bladder neck and prostate, resulting in the improvement in urine flow and a reduction in symptoms in benign prostate hyperplasia. Alfuzosin also inhibits the vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral vasodilation.

Vardenafil (Levitra) is an oral therapy for the treatment of erectile dysfunction. It is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Penile erection is a hemodynamic process initiated by the relaxation of smooth muscle in the corpus cavernosum and its associated arterioles. During sexual stimulation, nitric oxide is released from nerve endings and endothelial cells in the corpus cavernosum. Nitric oxide activates the enzyme guanylate cyclase resulting in increased synthesis of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum. The cGMP in turn triggers smooth muscle relaxation, allowing increased blood flow into the penis, resulting in erection. The tissue concentration of cGMP is regulated by both the rates of synthesis and degradation via phosphodiesterases (PDEs). The most abundant PDE in the human corpus cavernosum is the cGMPspecific phosphodiesterase type 5 (PDE5); therefore, the inhibition of PDE5 enhances erectile function by increasing the amount of cGMP.

Tadalafil is used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Part of the physiological process of erection involves the release of nitric oxide (NO) in the corpus cavernosum. This then activates the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation in the corpus cavernosum, resulting in increased inflow of blood and an erection. Tadalafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum. This means that, with tadalafil on board, normal sexual stimulation leads to increased levels of cGMP in the corpus cavernosum which leads to better erections. Without sexual stimulation and no activation of the NO/cGMP system, tadalafil should not cause an erection.Tadalafil inhibits the cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum located around the penis. Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) by tadalafil enhances erectile function by increasing the amount of cGMP. Tadalafil is used for the treatment of erectile dysfunction.