Tamsulosin is a medicine used for the symptoms of an enlarged prostate (benign prostatic hyperplasia), such as difficulty urinating or a weak stream. It relaxes the muscles of the prostate and bladder, making urination easier.
Also known as: Omnic, Flomax
Combining sildenafil with tamsulosin can lower blood pressure and cause dizziness or fainting, especially on standing.
Co-administration of PDE5 inhibitors with tamsulosin can cause symptomatic hypotension in some patients, due to the combined vasodilator effect. Although tamsulosin is more selective and has less haemodynamic interaction than other alpha-blockers (doxazosin, for example, showed a greater additive effect in studies), the tamsulosin label advises caution.
PDE5 + tamsulosin: risk of symptomatic hypotension documented in labels. Tamsulosin has less haemodynamic interaction than other alpha-blockers, but caution remains; stabilise and use a low starting dose.
Additive vasodilator effect (PDE5 + alpha-1 antagonist).
Orthostatic blood pressure and symptoms when starting the combination.
Dizziness on standing, syncope.
Stabilise tamsulosin before starting the PDE5; start low and assess tolerability.
DailyMed/FDA (NIH/NLM) — approved Tamsulosin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5ed219aa-cf65-457f-8570-d26b48edb240 ; PubMed — https://pubmed.ncbi.nlm.nih.gov/16387566/ ; Prontuário Terapêutico do INFARMED (11th ed., 2012)
Combining tadalafil with tamsulosin can lower blood pressure and cause dizziness or fainting, especially on standing.
Combining tadalafil with alpha-blockers can cause symptomatic hypotension. The tadalafil label does not recommend combining with alpha-blockers for BPH treatment (efficacy not studied and risk of blood pressure lowering) and advises caution when used for erectile dysfunction. In a study, tadalafil had little haemodynamic interaction with tamsulosin, but caution remains.
PDE5 + tamsulosin: the tadalafil label advises against the combination for BPH and advises caution in erectile dysfunction; a study showed little haemodynamic interaction with tamsulosin.
Additive vasodilator effect (PDE5 + alpha-1 antagonist).
Orthostatic blood pressure when starting the combination.
Dizziness on standing, syncope.
Use with caution; consider a low starting dose; monitor orthostatic symptoms.
DailyMed/FDA (NIH/NLM) — approved Tadalafil label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895 ; PubMed — https://pubmed.ncbi.nlm.nih.gov/15540759/ ; Prontuário Terapêutico do INFARMED (11th ed., 2012)
Ketoconazole raises tamsulosin blood levels (up to ~2.8-fold), with a higher risk of hypotension and dizziness.
Tamsulosin is metabolised by CYP3A4 and CYP2D6. Ketoconazole (400 mg/day) increased tamsulosin Cmax 2.2-fold and AUC 2.8-fold. Combining with strong CYP3A4 inhibitors should be avoided in CYP2D6 poor metabolisers and used with caution in others, due to the risk of hypotension and adverse effects.
CYP3A4: ketoconazole increased tamsulosin AUC ~2.8-fold. Do not use with strong CYP3A4 inhibitors in CYP2D6 poor metabolisers; use with caution in others.
CYP3A4 inhibition, reducing tamsulosin clearance.
Orthostatic blood pressure and tamsulosin adverse effects.
Dizziness, symptomatic hypotension, syncope.
Avoid the combination in CYP2D6 poor metabolisers; in others, use with caution and watch for hypotension.
DailyMed/FDA (NIH/NLM) — approved Tamsulosin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5ed219aa-cf65-457f-8570-d26b48edb240 ; approved Ketoconazole label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f162e616-21b4-49b1-b437-15e21001a6f0 ; EMC-UK (MHRA) — approved Tamsulosin SmPC: https://www.medicines.org.uk/emc/product/102038/smpc ; Prontuário Terapêutico do INFARMED (11th ed., 2012)
Tamsulosin should be taken about 30 minutes after the same meal every day to maintain stable concentrations and reduce exposure variability.
Take the capsule 30 minutes after the same daily meal; do not crush, chew or open the capsule.
DailyMed/FDA (NIH/NLM) — approved Tamsulosin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5ed219aa-cf65-457f-8570-d26b48edb240
Tamsulosin is contraindicated in patients with a history of orthostatic hypotension, due to the risk of syncope.
Do not use; if dizziness or weakness occurs when starting, sit or lie down and contact the doctor.
EMC-UK (MHRA) — approved Tamsulosin SmPC: https://www.medicines.org.uk/emc/product/102038/smpc ; Prontuário Terapêutico do INFARMED (11th ed., 2012)
Tamsulosin is contraindicated in severe hepatic impairment.
Do not use in severe hepatic impairment; in moderate impairment, use with caution.
EMC-UK (MHRA) — approved Tamsulosin SmPC: https://www.medicines.org.uk/emc/product/102038/smpc
Tamsulosin is associated with intraoperative floppy iris syndrome (IFIS) during cataract or glaucoma surgery.
Inform the ophthalmologist before surgery; prior discontinuation may be considered, although the benefit is not established.
DailyMed/FDA (NIH/NLM) — approved Tamsulosin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5ed219aa-cf65-457f-8570-d26b48edb240
Tamsulosin is not indicated for use in women; no pregnancy data are available.
Not indicated in women; no data in pregnancy.
Not indicated in women.
Not applicable (male-only drug).
EMC-UK (MHRA) — approved Tamsulosin SmPC: https://www.medicines.org.uk/emc/product/102038/smpc
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Selective alpha-1 blocker used in benign prostatic hyperplasia symptoms: it improves maximum urinary flow rate and reduces obstructive and irritative symptoms. It is not intended as an antihypertensive.
Selectively blocks alpha-1A adrenergic receptors, predominant in the prostate (about 70% of prostatic alpha-1 receptors), relaxing smooth muscle in the prostate, prostatic capsule, prostatic urethra and bladder neck and reducing bladder outlet obstruction.
Absorption is essentially complete (over 90%) when fasted, with a Tmax of 4 to 5 hours (6 to 7 hours with food). When fasted, bioavailability increases 30% (AUC) and Cmax 40 to 70%. It is 94 to 99% bound to plasma proteins, mainly to alpha-1 acid glycoprotein.
Extensively metabolised in the liver, mainly by CYP3A4 and CYP2D6 (with minor participation of other isoenzymes); less than 10% of the dose is excreted unchanged in urine. The metabolites undergo glucuronide or sulfate conjugation before renal excretion. Urine is the main route (76%) and faeces 21%.
The apparent half-life of tamsulosin capsules is approximately 9 to 13 hours in healthy volunteers and 14 to 15 hours in the target population; with the immediate-release formulation, the half-life is 5 to 7 hours.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
