Dutasteride is a synthetic 4-azasteroid compound that is a selective inhibitor of both the type 1 and type 2 isoforms of steroid 5 alpha-reductase (5AR), intracellular enzymes that convert testosterone to 5 alpha-dihydrotestosterone (DHT). Type I 5a-reductase is predominant in the sebaceous glands of most regions of skin, including scalp, and liver. Type I 5a-reductase is responsible for approximately one-third of circulating DHT. The Type II 5a-reductase isozyme is primarily found in prostate, seminal vesicles, epididymides, and hair follicles as well as liver, and is responsible for two-thirds of circulating DHT. Dutasteride inhibits the conversion of testosterone to 5 alpha-dihydrotestosterone (DHT), which is the androgen primarily responsible for the initial development and subsequent enlargement of the prostate gland. Testosterone is converted to DHT by the enzyme 5 alpha-reductase, which exists as 2 isoforms, type 1 and type 2. Dutasteride is a competitive and specific inhibitor of both type 1 and type 2 5 alpha-reductase isoenzymes, with which it forms a stable enzyme complex. Dissociation from this complex has been evaluated under in vitro and in vivo conditions and is extremely slow. Used for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate gland to improve symptoms, and reduce the risk of acute urinary retention and the need for surgery. Marketed under the brand name Avodart.

Sildenafil (Viagra, Revatio) is a PDE5 inhibitor which was approved by FDA for the treatment of erectile disfunction and adults with pulmonary arterial hypertension. Upon administration sildenafil inhibits PDE5 and results in elevated level of cyclic guanosine monophosphate and smooth muscle relaxation.

Tolterodine is competitive muscarinic receptors M3 and M2 antagonist. It was sold under trade names detrol for the treatment of overactive bladder with symptoms of urge urinary incontinence. Both urinary bladder contraction and salivation are mediated via cholinergic muscarinic receptors. After oral administration, tolterodine is metabolized in the liver, resulting in the formation of the 5-hydroxymethyl derivative, a major pharmacologically active metabolite. The 5-hydroxymethyl metabolite, which exhibits an antimuscarinic activity similar to that of tolterodine, contributes significantly to the therapeutic effect. Both tolterodine and the 5-hydroxymethyl metabolite exhibit a high specificity for muscarinic receptors, since both show negligible activity and affinity for other neurotransmitter receptors and other potential cellular targets, such as calcium channels. Tolterodine has a pronounced effect on bladder function. The main effects of tolterodine at 1 and 5 hours were an increase in residual urine, reflecting an incomplete emptying of the bladder, and a decrease in detrusor pressure. These findings are consistent with an antimuscarinic action on the lower urinary tract.

Tamsulosin, a sulfamoylphenethylamine-derivative alpha-adrenoceptor blocker with enhanced specificity for the alpha-adrenoceptors of the prostate, is commonly used to treat benign prostatic hyperplasia (BPH). The drug is commercially available in a racemic mixture of 2 isomers, and is pharmacologically related to doxazocin, prazosin, and terazosin. However, unlike these drugs, tamsulosin has a higher affinity for the alpha-1A- adrenergic receptors, which are located in vascular smooth muscle. Studies show that tamsulosin has about 12 times greater affinity for alpha-1 adrenergic receptors in the prostate than those in the aorta, which may result in a reduced incidence of adverse cardiovascular effects. Tamsulosin is sold under the trade name Flomax.

Finasteride is a synthetic 4-azasteroid compound. This drug is a competitive and specific inhibitor of Type II 5a-reductase, an intracellular enzyme that converts the androgen testosterone into 5α-dihydrotestosterone (DHT). Two distinct isozymes are found in mice, rats, monkeys, and humans: Type I and II. Each of these isozymes is differentially expressed in tissues and developmental stages. In humans, Type I 5a-reductase is predominant in the sebaceous glands of most regions of skin, including scalp, and liver. Type I 5a-reductase is responsible for approximately one-third of circulating DHT. The Type II 5a-reductase isozyme is primarily found in prostate, seminal vesicles, epididymides, and hair follicles as well as liver, and is responsible for two-thirds of circulating DHT. Although finasteride is 100-fold more selective for type II 5a-reductase than for the type I isoenzyme, chronic treatment with this drug may have some effect on type I 5a-reductase. Finasteride is used for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to: Improve symptoms, reduce the risk of acute urinary retention, reduce the risk of the need for surgery including transurethral resection of the prostate. Also used for the stimulation of regrowth of hair in men with mild to moderate androgenetic alopecia (male pattern alopecia, hereditary alopecia, common male baldness). Finasteride is sold under the brand names Proscar and Propecia among others.

Tiopronin is a prescription thiol drug used primarily in the treatment of severe homozygous cystinuria. Patients with cystinuria excrete high levels of cystine in their urine and are at risk for kidney stone formation. Tiopronin is used as a second-line therapy to control the rate of cystine precipitation and excretion, and prevent kidney stone formation. It is used after a failure of the non-pharmacological first line treatment consisting of increased fluid intake, restriction of sodium and protein, and urinary alkalinization. As cystinuria is a relatively rare disease, tiopronin is classified as an orphan drug and is not patented in the United States. It is similar to d-penicillamine in use and efficacy, but offers the advantage of far less adverse effects. Tiopronin is dosed on an individual basis using close monitoring of urinary cystine concentrations and urinary output. Tiopronin is a chelating agent. It works by removing extra cystine (the cause of kidney stones) from the urine, which keeps the kidney stones from forming. It works by reacting with urinary cysteine to form a more soluble, disulfide linked, tiopronin-cysteine complex.

Terazosin (marketed as Hytrin or Zayasel) is a selective alpha1-antagonist used for treatment of symptoms of benign prostatic hyperplasia (BPH). It also acts to lower blood pressure, so it is a drug of choice for men with hypertension and prostate enlargement. All three receptor subtypes appear to be involved in maintaining vascular tone. The α1A-receptor maintains basal vascular tone while the α1B-receptor mediates the vasocontrictory effects of exogenous α1-agonists. Activation of α1-receptors activates Gq-proteins, which results in intracellular stimulation of phospholipases C, A2, and D. This results in mobilization of Ca2+ from intracellular stores, activation of mitogen-activated kinase and PI3 kinase pathways and subsequent vasoconstriction.

Acetohydroxamic acid (also known as AHA or by the trade name Lithostat) is a synthetic drug derived from hydroxylamine and ethyl acetate, is similar in structure to urea. In the urine, it acts as an antagonist of the bacterial enzyme urease. Acetohydroxamic acid is used to lower the level of ammonia in the urine, which may help with some types of urinary infections. Acetohydroxamic Acid has no direct antimicrobial action and does not acidify urine directly. It is used, in addition to antibiotics or medical procedures, to treat chronic urea-splitting urinary infections. In 1983 the US Food and Drug Administration approved acetohydroxamic acid (AHA) as an orphan drug for "prevention of so-called struvite stones" under the newly enacted Orphan Drug Act of 1983.

Ecraprost [AS 013, Circulase] is a prodrug of prostaglandin E(1) within lipid microspheres that is being developed in Japan by Mitsubishi Pharma Corporation and Asahi Glass. It was originally in development with Welfide Corporation. On 1 October 2001, Welfide Corporation (formerly Yoshitomi) merged with Mitsubishi-Tokyo Pharmaceuticals to form Mitsubishi Pharma Corporation. The new company is a subsidiary of Mitsubishi Chemical. Taisho and Seikagaku Corporation had been involved in the development of ecraprost but discontinued their licences to do so. The effects of ecraprost on reperfusion injury, in preclinical studies, had been reported by Taisho. Ecraprost is in phase II in Japan and was in phase II in Europe for the treatment of peripheral arterial disease. It was also in a phase II study in the treatment of diabetic neuropathies. However, this is no longer an active indication. A phase III trial using a lipid emulsion of ecraprost [Circulase] is underway with Mitsubishi Pharma Corporation in the US, using ecraprost for the treatment of patients with severe peripheral arterial disease, which, because of decreased blood flow to the extremities, can lead to painful ulcers on the legs and feet and subsequent amputation. Alpha Therapeutic Corporation (a former subsidiary of Mitsubishi Pharma) was initially involved in trials of ecraprost in the US, but this responsibility has been taken over by the parent company.

Oxybutynin is an antispasmodic, anticholinergic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. Oxybutynin relaxes bladder smooth muscle. Oxybutynin exhibits only one-fifth of the anticholinergic activity of atropine on the rabbit detrusor muscle, but four to ten times the antispasmodic activity. Antimuscarinic activity resides predominantly in the R-isomer. Oxybutynin exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle. No blocking effects occur at skeletal neuromuscular junctions or autonomic ganglia (antinicotinic effects). By inhibiting particularily the M1 and M2 receptors of the bladder, detrusor activity is markedly decreased.