Tamsulosin Hydrochloride

Pronunciation

Pronunciation: tam-SOO-loe-sin HIGH-droe-KLOR-ide
Class: Alpha-1-adrenergic blocker

Trade Names

Flomax
- Capsules 0.4 mg

Novo-Tamsulosin (Canada)
Sandoz Tamsulosin (Canada)

Pharmacology

Selectively blocks alpha 1 -adrenergic receptors causing relaxation of prostate smooth muscle resulting in an increase in urinary flow rate and a reduction in symptoms of benign prostatic hypertrophy.

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Pharmacokinetics

Absorption

Tamsulosin absorption is greater than 90% (fasting), and T max is 4 to 5 h (fasting) and 6 to 7 h (with food). Taking tamsulosin under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak concentrations.

Distribution

Steady state is achieved by the fifth day of every day dosing. Vd is about 16 L. Tamsulosin is widely distributed to most tissues, including kidney, prostate, liver, gall bladder, heart, aorta, and brown fat. There is minimal distribution to brain, spinal cord, and testes. The drug is 94% to 99% protein bound.

Metabolism

Tamsulosin is extensively metabolized by CYP-450 in the liver.

Elimination

Tamsulosin t ½ is 5 to 7 h. Approximately 10% is excreted unchanged in urine.

Special Populations

Elderly

AUC is 40% higher in subjects 55 to 75 yr of age compared with subjects 20 to 32 yr of age.

Indications and Usage

Treatment of signs and symptoms of benign prostatic hyperplasia.

Contraindications

Standard considerations.

Dosage and Administration

Adults

PO 0.4 mg/day, administered approximately 30 min following the same meal each day. If the patient fails to respond after 2 to 4 wk, the dose may be increased to 0.8 mg/day.

Storage/Stability

Store at controlled room temperature (59° to 86°F). Protect from excessive moisture.

Drug Interactions

Cimetidine

Concomitant use may decrease tamsulosin Cl and increase the AUC. Use with caution.

Laboratory Test Interactions

None well documented.

Adverse Reactions

CNS

Headache (21%); dizziness (17%); somnolence (4%); decreased libido (2%); insomnia (1%).

EENT

Rhinitis (18%); pharyngitis (5%); amblyopia (2%).

GI

Diarrhea (6%); nausea (4%); tooth disorder (2%).

Genitourinary

Abnormal ejaculation (18%).

Respiratory

Increased cough (5%); sinusitis (4%).

Miscellaneous

Infection (11%); asthenia (9%); back pain (8%); chest pain (4%).

Precautions

Pregnancy

Category B .

Lactation

Not indicated for use in women.

Children

Safety and efficacy not established.

Hypertension

Tamsulosin is currently not indicated for the treatment of hypertension.

Priapism

Association is rare; can lead to permanent impotence if not properly treated.

Prostate cancer

Rule out before starting therapy.

Overdosage

Symptoms

Hypotension, severe headache.

Patient Information

  • Advise about the possibility of priapism, which requires immediate medical attention.
  • Advise patient to take prescribed dose every day, about 30 min after the same meal each day.
  • Advise patient not to crush, chew, or open capsule, and to swallow the capsule whole with a full glass of water.
  • Advise patient that dose may be increased after 2 to 4 wk to increase beneficial effects on the prostate gland. Caution patient that if a larger dose is being used and is interrupted for several days to restart therapy with the lower dose.
  • Caution patient to avoid sudden position changes to prevent orthostatic hypotension. If orthostatic hypotension does occur, instruct patient to sit or lie down.
  • Caution patient that drug may cause dizziness or drowsiness and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.
  • Instruct patient to report the following symptoms to the health care provider: dizziness, excessive drowsiness, fainting, sexual dysfunction.
  • Advise patient to contact health care provider if urinary symptoms do not improve or if they worsen while taking this medication.
  • Advise patient to read patient information leaflet before starting therapy and with each refill.

Copyright © 2009 Wolters Kluwer Health.

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