What is Tamsulosin?
Tamsulosin (rINN) ( /tæmˈsuːlɵsɨn/ or /tæmsʉˈloʊsɨn/)
is an ¦Á1a-selective alpha blocker used in the
symptomatic treatment of benign prostatic hyperplasia (BPH).
Tamsulosin was developed by Yamanouchi Pharmaceuticals
(now part of Astellas Pharma) and was first marketed in
1996 under the trade name Flomax. It is now marketed by
various companies under licence, including
Boehringer-Ingelheim and CSL.
Tamsulosin hydrochloride extended-release capsules are
marketed under the trade names Flomax, Flomaxtra,
Contiflo XL and Urimax, although generic,
non-modified-release capsules are still approved and
marketed in many countries (such as Canada). In Mexico
it is marketed as Secotex and as Harnal D in Japan and
Indonesia. In Egypt, Italy and Iceland, it is marketed
under the trade name Omnic by Astellas Pharma Europe.
Mechanism
Main article: Alpha blocker
Tamsulosin is a selective ¦Á1 receptor antagonist that
has preferential selectivity for the ¦Á1A receptor in the
prostate versus the ¦Á1B receptor in the blood vessels.
Clinical uses
Tamsulosin is primarily used for benign prostatic
hyperplasia, but is sometimes used for the passage of
kidney stones by the same mechanism of smooth muscle
relaxation via alpha antagonism.
Adverse effects
Two ADRs (Adverse Drug Reactions) have been reported:
Immunologic: It contains a sulfa moiety, thus
causing typical reactions to sulfa drugs.
Ophthalmologic: Patients taking tamsulosin are
prone to a complication known as floppy iris syndrome
during cataract surgery. Adverse outcomes of the surgery
are greatly reduced by the surgeon's prior knowledge of
the patient's history with this drug, and thus having
the option of alternative techniques.
Tamsulosin has also affected the sexual function in men.
Tamsulosin can cause males to experience retrograde
ejaculation. In males, retrograde ejaculation occurs
when the fluid to be ejaculated, which would normally
exit the body via the urethra, is redirected to the
urinary bladder. Normally, the sphincter of the bladder
contracts and the ejaculate goes to the urethra, the
area of least pressure. In retrograde ejaculation, this
sphincter does not function properly.
Occasionally, tamsulosin can cause a drop in blood
pressure, rarely resulting in dizziness or fainting.
Other reported side effects include headache, dizziness,
nasal congestion, and palpitations.
Clinical comparison
Although prostate specific, it does not have the
prostate apoptotic effects of other alpha-blockers such
as doxazosin and terazosin.
Use in combination therapy
The results of the CombAT (Combination of Avodart and
Tamsulosin) trial in 2008 demonstrated that treatment
with the combination of dutasteride (Avodart) and
tamsulosin provides greater symptom benefits compared to
monotherapy with either agent alone for treatment of
benign prostatic hyperplasia.
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Chemical Structure
Molecular Formula C20H28N2O5S
