COMPOSITION

Tamstream™ D
(Tamsulosin 0.4 mg + Dutasteride 0.5 mg Tablet)


Tamsulosin: Refer Tamstream™
CombAT study proved that, combination therapy significantly improved treatment satisfaction among pateints, when compared with either monotherapy. Combined therapy was better than dutasteride monotherapy in men with prostate volumes of ≥30 to < 58 mL, but not in men with a prostate volume of ≥ 58 mL.

Dutasteride

Category: 5-α reductase inhibitor

Mechanism of Action

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-reductaseisoenzymes, with which it forms a stable enzyme complex.

Pharmacokinetics

Absorption
Absolute bioavailability is approximately 60% (range, 40% to 94%). When the drug is administered with food, the maximum serum concentrations were reduced by 10% to 15%. This reduction is of no clinical significance.
Distribution
Oral doses show that dutasteride has a large volume of distribution (300 to 500 L). Dutasteride is highly bound to plasma albumin (99.0%) and alpha-1 acid glycoprotein (96.6%).
Metabolism and Elimination
Dutasteride is extensively metabolized in humans. In human serum unchanged dutasteride, 3 major metabolites (4'-hydroxydutasteride, 1,2-dihydrodutasteride, and 6-hydroxydutasteride), and 2 minor metabolites (6,4' -dihydroxydutasteride and 15-hydroxydutasteride), have been detected.
Dutasteride and its metabolites were excreted mainly in feces. As a percent of dose, there was approximately 5% unchanged dutasteride (~1% to ~15%) and 40% as dutasteride-related metabolites (~2% to ~90%). Only trace amounts of unchanged dutasteride were found in urine (<1%).

Indications

This medication is used in men to treat the symptoms of an enlarged prostate (benign prostatic hyperplasia-BPH). It works by reducing the size of the enlarged prostate. This helps to relieve symptoms of BPH such as difficulty in beginning the flow of urine, weak stream, and the need to urinate frequently or urgently (including during the middle of the night). It may also reduce the need for surgery to treat BPH. Dutasteride is not approved for prevention of prostate cancer. It may slightly increase the risk of developing a very serious form of prostate cancer.

Side Effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

 Difficulty achieving or maintaining an erection (impotence).
 Decreased libido.
 Ejaculation disorders, such as decreased amount of semen produced or decreased sperm count.
 Breast enlargement or tenderness.
 Allergic reactions such as rash, itching or localised swelling.
 Dizziness.
 Hair loss (primarily body hair) or increased hair growth.

Dutasteride Pregnancy Warnings

Dutasteride has been assigned to pregnancy category X by the FDA. There are no controlled data in human pregnancy. Preclinical data have suggested that the suppression of circulating levels of dihydrotestosterone (DHT) may inhibit the development of the external genital organs in a male fetus carried by a woman exposed to dutasteride. Feminization of male fetuses is and expected psychological consequence of inhibition of the conversion of testosterone to DHT. Dutasteride is considered contraindicated for use in women.