tamsulosin hydrochloride
Meaning of tamsulosin hydrochloride: It does not shrink the prostate at all; it slackens the muscle wrapped around the outlet, so any relief arrives within days.
Definition of tamsulosin hydrochloride
Tamsulosin hydrochloride is a drug that relaxes the smooth muscle of the prostate, the bladder neck and the tube running through the gland, widening the outlet so urine flows more freely. It is used for the urinary symptoms of an enlarged prostate. It belongs to the alpha blocker group and acts selectively on a receptor concentrated in those tissues rather than in blood vessel walls.
Why does relaxing muscle help?
An enlarged prostate obstructs in two ways. Part of the problem is bulk, the gland pressing physically on the tube it surrounds. The other part is tone: smooth muscle within the gland and around the bladder outlet is held partly contracted by nerve signals, and that tension narrows the channel further. Tamsulosin acts on the second component only. Blocking the receptor that maintains the tension lets the muscle slacken, so the channel widens while the size of the gland stays exactly as it was.
How does it compare with the other drugs used?
| Group | What it does | Time to effect |
|---|---|---|
| Alpha blockers | Relax muscle at the outlet | Days |
| 5-alpha-reductase inhibitors | Shrink the gland by lowering a hormone | Months |
| The two combined | Both effects together | Days, with further gain later |
Because the groups address different components, they are often used together where the prostate is large. Neither reverses the underlying enlargement.
What follows from the selectivity?
Older alpha blockers acted on receptors in blood vessel walls as well, lowering blood pressure and causing dizziness on standing. Tamsulosin favors the subtype found in the urinary tract, so that effect is reduced though not abolished, particularly with the first few doses. A different consequence is common: the same slackening at the bladder neck lets semen pass backward into the bladder at orgasm instead of outward, which is harmless and reverses when the drug is stopped.
Why does eye surgery come into it?
The iris carries the same receptor. In people who have taken the drug the iris can turn floppy and billow during cataract surgery, narrowing the pupil unexpectedly and complicating the operation. The effect persists long after the last dose, which is why the drug history rather than only current use is recorded before the procedure.
Also known as
Used in a sentence
Tamsulosin hydrochloride was started for moderate lower urinary tract symptoms.
Good to know
The receptor tamsulosin blocks is also present in the iris, and intraoperative floppy iris syndrome can complicate cataract surgery in people who have taken the drug, including those who stopped it long beforehand.