Tamsulosin
JFDA label: Omnic Ocas
Mechanism of Action
Tamsulosin is an antagonist of alpha1A-adrenoreceptors in the prostate. Smooth muscle tone in the prostate is mediated by alpha1A-adrenoreceptors; blocking them leads to relaxation of smooth muscle in the bladder neck and prostate causing an improvement of urine flow and decreased symptoms of BPH. Approximately 75% of the alpha1-receptors in the prostate are of the alpha1A subtype.
Indications
Approved
- Benign prostatic hyperplasia
Off-label
- Bladder outlet obstruction symptoms
- Ureteral calculi (distal)
Contraindications
Source: Lexicomp
- Additional contraindications (not in US labeling): Concomitant use with strong CYP3A4 inhibitors (including ketoconazole) Absolute
- Hypersensitivity (eg, angioedema, rash, urticaria, pruritus, respiratory symptoms) to tamsulosin or any component of the formulation Absolute
Adverse Reactions
Cardiac disorders (1)
Very Common Orthostatic hypotension Central nervous system: Headache, dizziness
Nervous system disorders (3)
Common Drowsiness · insomnia · vertigo
Renal and urinary disorders (1)
Very Common Ejaculation failure
Metabolism and nutrition disorders (1)
Common Loss of libido
Gastrointestinal disorders (2)
Common Diarrhea · nausea
Musculoskeletal and connective tissue disorders (2)
Common back pain · Weakness
Eye disorders (1)
Common Blurred vision
Infections and infestations (1)
Very Common Infection
Respiratory, thoracic and mediastinal disorders (4)
Very Common Rhinitis
Common cough · Pharyngitis · sinusitis
Dosing
Source: Lexicomp
Warnings & Precautions
Source: Lexicomp
Angina
Discontinue if symptoms of angina occur or worsen.
Floppy iris syndrome
Intraoperative floppy iris syndrome (IFIS) is characterized by a combination of flaccid iris that billows with intraoperative currents, progressive intraoperative miosis despite dilation, and potential iris prolapse. IFIS has been observed in cataract and glaucoma surgery patients who were on or were previously treated with alpha1-blockers, particularly with tamsulosin use (Abdel-Aziz, 2009); in some cases, patients had discontinued the alpha1-blocker 5 weeks to 9 months prior to the surgery. The benefit of discontinuing alpha-blocker therapy prior to cataract or glaucoma surgery has not been established. IFIS may increase the risk of ocular complications during and after surgery. May require modifications to surgical technique; instruct patients to inform ophthalmologist of current or previous alpha1-blocker use when considering eye surgery. Initiation of tamsulosin therapy in patients with planned cataract or glaucoma surgery is not recommended.
Orthostatic hypotension/syncope
May cause significant orthostatic hypotension and syncope, especially with first dose; anticipate a similar effect if therapy is interrupted for a few days, if dosage is rapidly increased, or if another antihypertensive drug (particularly vasodilators) or a PDE-5 inhibitor (eg, sildenafil, tadalafil, vardenafil) is introduced. “First-dose” orthostatic hypotension may occur 4-8 hours after dosing; may be dose related. Patients should be cautioned about performing hazardous tasks, driving, or operating heavy machinery when starting new therapy or adjusting dosage upward.
Priapism
Priapism has been associated with use (rarely).
Sulfonamide allergy
Rarely, patients with a sulfa allergy have also developed an allergic reaction to tamsulosin; avoid use when previous reaction has been severe or life-threatening. Disease-related concerns:
Heart failure
In a scientific statement from the American Heart Association, tamsulosin has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: moderate) (AHA [Page 2016]).
Prostate cancer
It is recommended to rule out prostatic carcinoma with screening before beginning therapy and then screen at regular intervals. Concurrent drug therapy issues:
Limitation of use
Not intended for use as an antihypertensive drug.
Pregnancy & Lactation
Pregnancy
Adverse events were not observed in animal reproduction studies. For pregnant women with kidney stones, other treatments such as stents or ureteroscopy, are recommended if stone removal is needed (Preminger, 2007; Tan, 2013).
Lactation
If tamsulosin is required by the mother, it is not a reason to discontinue breastfeeding.
Monitoring
| Clinical pearl | Blood pressure; urinary symptoms |
|---|
Chemistry & Properties
| Formula | C20H28N2O5S |
|---|---|
| Molecular weight | 408.52 g/mol |
| IUPAC name | 5-[(2R)-2-[2-(2-ethoxyphenoxy)ethylamino]propyl]-2-methoxybenzenesulfonamide |
| CAS | 106133-20-4 |
| PubChem CID | 129211 |
| InChIKey | DRHKJLXJIQTDTD-OAHLLOKOSA-N |
| logP | 2.34 (XLogP 2.7) |
| Polar surface area | 99.88 Ų |
| H-bond acceptors / donors | 6 / 2 |
| Drug-likeness (QED) | 0.55 |
| Lipinski violations | 0 |
SMILES
CCOc1ccccc1OCCN[C@H](C)Cc1ccc(OC)c(S(N)(=O)=O)c1Biology & Pharmacokinetics
Pharmacokinetics
| BBB penetrant | No |
|---|
Enzyme interactions
| Enzyme | Role | Detail |
|---|---|---|
| CYP1A2 | Inhibitor | — |
| CYP2B6 | Inhibitor | — |
| CYP2C8 | Inhibitor | — |
| CYP2D6 | Inhibitor | — |
| CYP2D6 | Substrate | — |
| CYP3A4 | Substrate | — |
Receptor binding (top 5)
| Target | Action | Affinity |
|---|---|---|
| alpha1A | Binding | pKi 10.2 |
| adrenergic Alpha1A (ADRA1A) | Binding | pKi 9.9 |
| alpha1B | Binding | pKi 9.9 |
| adrenergic Alpha1D (ADRA1D) | Binding | pKi 9.8 |
| adrenergic Alpha1B (ADRA1B) | Binding | pKi 8.8 |
Transporters
BCRP (Inhibitor)BSEP (Inhibitor)MRP1 (Inhibitor)OATP1B1 (Inhibitor)OATP1B3 (Inhibitor)P-gp (Inhibitor)MDR1 (Substrate)P-gp (Substrate)
Drug–drug interactions (73, DDInter)
| Interacting drug | Severity | Management |
|---|---|---|
| Ceritinib | major | |
| Clarithromycin | major | |
| Cobicistat | major | |
| Idelalisib | major | |
| Ketoconazole | major | |
| Abiraterone | moderate | |
| Alimemazine | moderate | |
| Amifostine | moderate | |
| Apalutamide | moderate | |
| Aprepitant | moderate | |
| Brimonidine (ophthalmic) | moderate | |
| Brimonidine (topical) | moderate | |
| Bupropion | moderate | |
| Canagliflozin | moderate | |
| Celecoxib | moderate | |
| Chlorphenesin | moderate | |
| Cimetidine | moderate | |
| Cinacalcet | moderate | |
| Clotrimazole | moderate | |
| Codeine | moderate | |
| Crizotinib | moderate | |
| Dabrafenib | moderate | |
| Dacomitinib | moderate | |
| Dapagliflozin | moderate | |
| Dexfenfluramine | moderate | |
| Diphenhydramine | moderate | |
| Doxepin | moderate | |
| Doxepin (topical) | moderate | |
| Dronabinol | moderate | |
| Eliglustat | moderate | |
| Empagliflozin | moderate | |
| Enzalutamide | moderate | |
| Epoprostenol | moderate | |
| Ertugliflozin | moderate | |
| Erythromycin | moderate | |
| Ethanol | moderate | |
| Fedratinib | moderate | |
| Fenfluramine | moderate | |
| Fluconazole | moderate | |
| Fostamatinib | moderate |
Showing 40 of 73.
Registered Products (11)
| Brand | Form / strength | Pack | Agent | Citizen (JOD) |
|---|---|---|---|---|
| Tamucas PR 0.4 mg Prolonged Release Film Coated Tablets | Film-Coated Tablet 0.4 mg | 30 tab | Sukhtian Group | 6.980 |
| Prostanic XR | Tablet 0.4 mg | 30 tab pack varies | AL-TAQADDOM PHARMACEUTICAL INDUSTRIES/JORDAN | 7.060 |
| Tamsin | Tablet 0.4 mg | 30 tab | Hikma Pharmaceuticals Co.Ltd/Jordan | 7.200 |
| Eziflo | Tablet 0.4 mg | 30 tab | UNITED PHARM.MFG.CO.LTD(UPM)/JORDAN | 9.080 |
| Tamzoman 0.4 mg F.C.Tablet | Film-Coated Tablet 0.4 mg | 30 tab | SAVVY PHARMA/JORDAN | 9.260 |
| Gamcet 0.4mg F.C Tab | Film-Coated Tablet 0.4 mg | 30 tab | Dar Al Dawa Development and Investment Co Ltd/Jordan | 9.510 |
| Prostanic | Tablet 0.4 mg | 30 tab pack varies | Al-Taqqadom Pharmaceutical Industries | 9.550 |
| Uriflo | Tablet 0.4 mg | 30 tab | pharma international | 9.670 |
| Omnic Ocas | Tablet 0.4 mg | 30 tab | Ibn Rushd Drug Store | 10.990 |
| Prostanic Plus | Capsule 0.4 mg, 0.5 mg | 30 cap | Altaqadom Pharmaceutical Industries | 19.530 |
| Gamcet Duo Capsules | Capsule 0.4 mg, 0.5 mg | 30 cap | / Dar Al Dawa Development and Investment Co Ltd/Jordan / General | 20.960 |