Pronunciation

(tam SOO loe sin)

Index Terms

• Tamsulosin HCl
• Tamsulosin Hydrochloride

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Capsule, Oral, as hydrochloride:

Flomax: 0.4 mg [contains fd&c blue #2 (indigotine)]

Generic: 0.4 mg

Brand Names: U.S.

• Flomax

Pharmacologic Category

• Alpha₁ Blocker

Pharmacology

Tamsulosin is an antagonist of alpha_1A-adrenoreceptors in the prostate. Smooth muscle tone in the prostate is mediated by alpha_1A-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 alpha_1A subtype.

Absorption

>90%

Distribution

V_d: 16 L

Metabolism

Hepatic (extensive) via CYP3A4 and 2D6; metabolites undergo extensive conjugation to glucuronide or sulfate

Excretion

Urine (76%, <10% as unchanged drug); feces (21%)

Time to Peak

Fasting: 4-5 hours; With food: 6-7 hours

Steady-state: By the fifth day of once daily dosing

Half-Life Elimination

Healthy volunteers: 9-13 hours; Target population: 14-15 hours

Protein Binding

94% to 99%, primarily to alpha₁ acid glycoprotein (AAG)

Special Populations: Elderly

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

Use: Labeled Indications

Benign prostatic hyperplasia: Treatment of signs and symptoms of benign prostatic hyperplasia (BPH)

Limitations of use: Not indicated for the treatment of hypertension.

Off Label Uses

Bladder outlet obstruction symptoms

Data from a retrospective nonrandomized study in patients with urinary tract symptoms suggestive of bladder outlet obstruction who received treatment with alpha blockers suggests that tamsulosin may be an effective treatment option for managing symptoms suggestive of lower urinary tract obstruction ^{[Rossi 2001]}. Additional trials may be necessary to further define the role of tamsulosin in this condition.

Ureteral calculi (distal)

Use of alpha-1 blockers, including tamsulosin, for treating ureteral calculi is recommended by US and European guidelines and is supported by data from meta-analyses as well as numerous controlled trials. Tamsulosin has been shown to be effective in facilitating expulsion of ureteral stones (less than 10 mm) as medical therapy alone or as an adjunct to shock wave lithotripsy and ureteroscopy. Some trials indicate a class effect of alpha-1 adrenergic blockers, with tamsulosin reported to be equally effective as terazosin, doxazosin, and alfuzosin.

Contraindications

Hypersensitivity to tamsulosin or any component of the formulation

Dosing: Adult

Benign prostatic hyperplasia (BPH): Males: Oral: 0.4 mg once daily ~30 minutes after the same meal each day; dose may be increased after 2 to 4 weeks to 0.8 mg once daily in patients who fail to respond. If therapy is discontinued or interrupted for several days, restart with 0.4 mg once daily.

Bladder outlet obstruction symptoms (off-label use): Oral: 0.4 mg once daily (Rossi, 2001)

Ureteral calculi (distal) expulsion (off-label use): Oral: 0.4 mg once daily, discontinue after successful expulsion (average time to expulsion was 1 to 2 weeks) (Agrawal, 2009; Ahmed, 2010). Note: Patients with stones >10 mm were excluded from studies.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

CrCl ≥10 mL/minute: No dosage adjustment necessary.

CrCl <10 mL/minute: There are no dosage adjustments provided in the manufacturer’s labeling (has not been studied).

Dosing: Hepatic Impairment

Mild-to-moderate impairment: No dosage adjustment is necessary.

Severe impairment: There are no dosage adjustments provided in the manufacturer’s labeling (has not been studied).

Administration

Administer 30 minutes after the same mealtime each day. Capsules should be swallowed whole; do not crush, chew, or open.

Storage

Store at 25°C (77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F).

Drug Interactions

Alpha-/Beta-Agonists: Alpha1-Blockers may diminish the vasoconstricting effect of Alpha-/Beta-Agonists. Similarly, Alpha-/Beta-Agonists may antagonize Alpha1-Blocker vasodilation. Monitor therapy

Alpha1-Agonists: Alpha1-Blockers may diminish the vasoconstricting effect of Alpha1-Agonists. Similarly, Alpha1-Agonists may antagonize Alpha1-Blocker vasodilation. Monitor therapy

Alpha1-Blockers: May enhance the antihypertensive effect of other Alpha1-Blockers. Avoid combination

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. Consider therapy modification

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Aprepitant: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Benperidol: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Beta-Blockers: May enhance the orthostatic hypotensive effect of Alpha1-Blockers. The risk associated with ophthalmic products is probably less than systemic products. Exceptions: Levobunolol; Metipranolol. Monitor therapy

Blood Pressure Lowering Agents: May enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Bosentan: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Calcium Channel Blockers: Alpha1-Blockers may enhance the hypotensive effect of Calcium Channel Blockers. Monitor therapy

Cimetidine: May increase the serum concentration of Tamsulosin. Monitor therapy

Conivaptan: May increase the serum concentration of CYP3A4 Substrates. Avoid combination

CYP2D6 Inhibitors (Strong): May increase the serum concentration of Tamsulosin. Monitor therapy

CYP3A4 Inducers (Moderate): May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

CYP3A4 Inducers (Strong): May increase the metabolism of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

CYP3A4 Inhibitors (Moderate): May decrease the metabolism of CYP3A4 Substrates. Monitor therapy

CYP3A4 Inhibitors (Strong): May increase the serum concentration of Tamsulosin. Avoid combination

Dabrafenib: May decrease the serum concentration of CYP3A4 Substrates. Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification

Dapoxetine: May enhance the orthostatic hypotensive effect of Alpha1-Blockers. Monitor therapy

Dasatinib: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Deferasirox: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Enzalutamide: May decrease the serum concentration of CYP3A4 Substrates. Management: Concurrent use of enzalutamide with CYP3A4 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP3A4 substrate should be performed with caution and close monitoring. Consider therapy modification

Fosaprepitant: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Fusidic Acid (Systemic): May increase the serum concentration of CYP3A4 Substrates. Avoid combination

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Idelalisib: May increase the serum concentration of CYP3A4 Substrates. Avoid combination

Levodopa: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa. Monitor therapy

Lormetazepam: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Mitotane: May decrease the serum concentration of CYP3A4 Substrates. Management: Doses of CYP3A4 substrates may need to be adjusted substantially when used in patients being treated with mitotane. Consider therapy modification

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Netupitant: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nitroprusside: Blood Pressure Lowering Agents may enhance the hypotensive effect of Nitroprusside. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

Palbociclib: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Pholcodine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Pholcodine. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Alpha1-Blockers. Management: Ensure patient is stable on one agent prior to initiating the other, and always initiate combination using the lowest possible dose of the drug being added. When tadalafil is used for treatment of BPH, concurrent alpha 1-blockers are not recommended. Consider therapy modification

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Rilmenidine: Alpha1-Blockers may enhance the hypotensive effect of Rilmenidine. Monitor therapy

Sarilumab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Siltuximab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Simeprevir: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

St John's Wort: May decrease the serum concentration of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

Stiripentol: May increase the serum concentration of CYP3A4 Substrates. Management: Use of stiripentol with CYP3A4 substrates that are considered to have a narrow therapeutic index should be avoided due to the increased risk for adverse effects and toxicity. Any CYP3A4 substrate used with stiripentol requires closer monitoring. Consider therapy modification

Tocilizumab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Adverse Reactions

>10%:

Cardiovascular: Orthostatic hypotension (first dose: 6% to 19%; symptomatic orthostatic hypotension (chronic therapy) <1%)

Central nervous system: Headache (19% to 21%), dizziness (15% to 17%)

Genitourinary: Ejaculation failure (8% to 18%)

Infection: Infection (9% to 11%)

Respiratory: Rhinitis (13% to 18%)

1% to 10%:

Central nervous system: Drowsiness (3% to 4%), insomnia (1% to 2%), vertigo (≤1%)

Endocrine & metabolic: Loss of libido (2%)

Gastrointestinal: Diarrhea (6%), nausea (4%)

Neuromuscular & skeletal: Weakness (8% to 9%), back pain (7% to 8%)

Ophthalmic: Blurred vision (≤2%)

Respiratory: Pharyngitis (6%), cough (3% to 5%), sinusitis (4%)

<1% (Limited to important or life-threatening): Epistaxis, exfoliative dermatitis, hypersensitivity reaction, hypotension, intraoperative floppy iris syndrome, palpitations, priapism, syncope

Warnings/Precautions

Concerns related to adverse effects:

• 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:

• Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Other warnings/precautions:

• Limitation of use: Not intended for use as an antihypertensive drug.

Monitoring Parameters

Blood pressure; urinary symptoms

Pregnancy Risk Factor

B

Pregnancy Considerations

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).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience headache, sexual dysfunction, back pain, cough, diarrhea, rhinitis, rhinorrhea, or loss of strength and energy. Have patient report immediately to prescriber severe dizziness, passing out, blurred vision, angina, tachycardia, arrhythmia, chills, pharyngitis, shortness of breath, or priapism (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.