Chemical formula: C₂₀H₂₈N₂O₅S Molecular mass: 408.512 g/mol PubChem compound: 129211
Tamsulosin interacts in the following cases:
Concomitant administration of tamsulosin hydrochloride with strong inhibitors of CYP3A4 may lead to increased exposure to tamsulosin hydrochloride. Concomitant administration with ketoconazole (a known strong CYP3A4 inhibitor) resulted in an increase in AUC and Cmax of tamsulosin hydrochloride by a factor of 2.8 and 2.2, respectively.
Tamsulosin hydrochloride should not be given in combination with strong inhibitors of CYP3A4 in patients with poor metaboliser CYP2D6 phenotype.
Tamsulosin hydrochloride should be used with caution in combination with strong and moderate inhibitors of CYP3A4.
Tamsulosin hydrochloride should be used with caution in combination with strong and moderate inhibitors of CYP3A4.
Concomitant administration of tamsulosin hydrochloride with paroxetine, a strong inhibitor of CYP2D6, resulted in a Cmax and AUC of tamsulosin that had increased by a factor of 1.3 and 1.6, respectively, but these increases are not considered clinically relevant.
Concurrent administration of other α1-adrenoceptor antagonists with tamsulosin could lead to hypotensive effects.
Concomitant cimetidine brings about a rise in plasma levels of tamsulosin, but as levels remain within the normal range posology need not be adjusted.
Diclofenac may increase the elimination rate of tamsulosin.
Concomitant furosemide brings about a fall in plasma levels of tamsulosin, but as levels remain within the normal range posology need not be adjusted.
Warfarin may increase the elimination rate of tamsulosin.
The ‘Intraoperative Floppy Iris Syndrome’ (IFIS, a variant of small pupil syndrome) has been observed during cataract surgery in some patients on or previously treated with tamsulosin hydrochloride. IFIS may increase the risk of eye complications during and after the operation.
Discontinuing tamsulosin hydrochloride 1–2 weeks prior to cataract surgery is anecdotally considered helpful, but the benefit of treatment discontinuation has not yet been established. IFIS has also been reported in patients who had discontinued tamsulosin for a longer period prior to cataract surgery.
The initiation of therapy with tamsulosin hydrochloride in patients for whom cataract surgery is scheduled is not recommended. During pre-operative assessment, cataract surgeons and ophthalmic teams should consider whether patients scheduled for cataract surgery are being or have been treated with tamsulosin in order to ensure that appropriate measures will be in place to manage the IFIS during surgery.
Tamsulosin is not indicated for use in women.
Tamsulosin is not indicated for use in women.
No data is available on whether tamsulosin adversely affects the ability to drive or operate machines. However, in this respect patients should be aware of the fact that drowsiness, blurred vision, dizziness and syncope can occur.
The adverse reactions are described according to the MedDRA system organ class in the table below.
| MedDRA System Organ Class | Common (≥1/100 to <1/10) | Uncommon (≥1/1,000 to <1/100) | Rare (≥1/10,000 to <1/1,000) | Very rare (<1/10,000) | Not known (cannot be estimated from the available data) |
|---|---|---|---|---|---|
| Nervous system disorders | Dizziness (1.3%) | Headache | Syncope | ||
| Eye disorders | Vision blurred*, Visual impairment* | ||||
| Cardiac disorders | Palpitations | ||||
| Vascular disorders | Orthostatic hypotension | ||||
| Respiratory, thoracic and mediastinal disorders | Rhinitis | Epistaxis* | |||
| Gastrointestinal disorders | Constipation, Diarrhoea, Nausea, Vomiting | Dry mouth* | |||
| Skin and subcutaneous tissue disorders | Rash, Pruritus, Urticaria | Angioedema | Stevens-Johnson syndrome | Erythema multiforme*, Dermatitis exfoliative* | |
| Reproductive system and breast disorders | Ejaculation disorders including retrograde ejaculation and ejaculation failure | Priapism | |||
| General disorders and administration site conditions | Asthenia |
* observed post-marketing
As with other alpha-blockers, drowsiness, blurred vision or oedema can occur.
During cataract and glaucoma surgery a small pupil situation, known as Intraoperative Floppy Iris Syndrome (IFIS), has been associated with therapy of tamsulosin during post-marketing surveillance.
In addition to the adverse events listed above, atrial fibrillation, arrhythmia, tachycardia and dyspnoea have been reported in association with tamsulosin use. Because these spontaneously reported events are from the worldwide post-marketing experience, the frequency of events and the role of tamsulosin in their causation cannot be reliably determined.
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