Tamsulosin hydrochloride is the first in the class of potent and selective α- 1A
adrenoceptor antagonists introduced for the treatment of dysuria associated with benign
prostatic hypertrophy (BPH). In a clinical study, significant improvement in irritative and
obstructive symptoms has been reported for tamsulosin treated patients with BPH. ln vitro
studies in human penile erectile tissue and vas deferens indicated that tamsulosin may be of
use in treating male sexual dysfunction.
ChEBI: Tamsulosin is a 5-(2-{[2-(2-ethoxyphenoxy)ethyl]amino}propyl)-2-methoxybenzenesulfonamide that has (R)-configuration. A specific alpha1 adrenoceptor antagonist used (generally as its hydrochloride salt, tamsulosin hydrochloride) in the treatment of prostatic hyperplasia, chronic prostatitis, urinary retention, and help with the passage of kidney stones. It has a role as an alpha-adrenergic antagonist and an antineoplastic agent. It is a conjugate base of a tamsulosin(1+). It is an enantiomer of an ent-tamsulosin.
In 1,000 ml of acetonitrile was suspended 17 g of 5-{2-[2-(2-
ethoxyphenoxy)ethylamino]-1-hydroxy-2-methylethyl}-2-
methoxybenzenesulfonamide hydrochloride and while stirring the suspension,
9 g of thionyl chloride was added dropwise to the suspension at room
temperature, whereby the product first dissolved and then began to crystallize
gradually. After stirring the mixture for two days, the crystals formed were
recovered by filtration, washed with chloroform and dried to provide 15 g of
5-{1-chloro-2-[2-(2-ethoxyphenoxy)ethylamino]-2-methylethyl}-2-
methoxybenzenesulfonamide hydrochloride. Melting point: 197°-200°C.
In methanol was dissolved the 5-{1-chloro-2-[2-(2-
ethoxyphenoxy)ethylamino]ethyl}-2-methoxybenzenesulfonamide
hydrochloride and after adding thereto 10% palladium carbon, dechlorination
was performed under hydrogen stream at normal temperature and pressure.
The palladium carbon was filtered away and the filtrate was concentrated
under reduced pressure to provide the 2-methoxy-5-{2-[2-(2-
ethoxyphenoxy)ethylamino]ethyl}benzenesulfonamide hydrochloride, which
was recrystallized from 120 ml of a mixture of methanol and ethanol (1:4 by
volume ratio) to provide the colorless crystals thereof. The melting point of
the 5-{2-[2-(2-ethoxyphenoxy)ethylamino]-2-methylethyl}-2-
methoxybenzenesulfonamide hydrochloride: 254°-256°C.
Tamsulosin (Flomax), a nonquinazoline benzensulfonamide,is the first in the class of subtype selective 1Ablocker.It is many folds more selective for α1A-receptorsthan for the other α1-receptors. This selectivity may favorblockade of α1A-receptors found in the prostate gland overthose found in vascular tissue. Tamsulosin is efficacious inthe treatment of BPH with little effect on blood pressure.Orthostatic hypotension is not as great with this agent aswith the nonselective quinazolines.
