Tamsulosin Hydrochloride + Dutasteride interactions

Food & lifestyle

• alcohol

  Moderate

  Synergy

  The concurrent use of ethanol and alpha-1 adrenergic blockers may cause increased hypotensive effects. Patients with aldehyde dehydrogenase deficiencies (primarily Asians) may be at a higher risk of this interaction. The mechanism has not been determined. Data exist for prazosin and other alpha adrenergic blockers are expected to interact also. In addition, any patients taking alpha adrenergic blockers may experience excessive orthostatic hypotension with ethanol ingestion, due to ethanol's unopposed vasodilatory effects in the presence of alpha adrenergic blockade.

  What to do: Patients who develop a flushing reaction after ethanol ingestion (indicates a possible aldehyde dehydrogenase deficiency) should be advised to avoid ethanol or limit their intake. All patients should be warned about the possibility of orthostatic hypotension with concurrent ethanol use.

  2 sources

  1. Kawano Y, Abe H, Kojima S, Takishita S, Omae T "Interaction of alcohol and an a1-blocker on ambulatory blood pressure in patients with essential hypertension." Am J Hypertens 13 (2000): 307-12
  2. "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo Canada Inc (2002):

• high-fat foods

  Moderate

  Absorption

  Food may delay the gastrointestinal absorption of tamsulosin. The time to maximum plasma concentration (Tmax) is reached by 4 to 5 hours under fasted conditions and by 6 to 7 hours when tamsulosin is administered with food. The delay in Tmax has the desirable effect of smoothing the tamsulosin plasma concentration profile, thereby reducing fluctuation of the plasma peak and trough concentrations with multiple dosing. Food may also affect the extent of absorption of tamsulosin. It has been reported that taking tamsulosin under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak plasma concentration (Cmax) compared to fed conditions. The effects of food on the pharmacokinetics of tamsulosin are consistent regardless of whether tamsulosin is taken with a light meal or a high-fat meal.

  What to do: To ensure uniformity of absorption, tamsulosin should be administered approximately one-half hour following the same meal each day.

  1 source

  1. "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim (2001):

Conditions

Conditions in which Tamsulosin Hydrochloride + Dutasteride needs care, as documented in this source.

• Glaucoma

  Major

  Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract and glaucoma surgery in some patients on or previously treated with alpha 1 blockers, including tamsulosin. The initiation of therapy with tamsulosin in patients for whom cataract or glaucoma surgery is scheduled is not recommended. The patient's ophthalmologist should be aware if the patient is receiving treatment with this drug and should be prepared for possible modifications to the surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances.

  1 source

  1. "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim (2001):

• Hypotension

  Moderate

  Peripheral alpha 1- adrenergic receptor blocking agents (aka alpha 1- blockers) cause vasodilation and can produce marked hypotension, especially orthostatic hypotension with syncope or other postural symptoms such as dizziness, lightheadedness, and palpitations. Orthostatic effects are most common during initiation of therapy and often occur within 90 minutes after the first dose. However, they can also occur following a dosage increase or resumption of therapy after an interruption of more than a few days. Agents with alpha 1a specificity, such as tamsulosin, act primarily on the prostate but are not devoid of hypotensive effects. Therapy with peripheral alpha-1 blockers should be administered cautiously in patients with or predisposed to hypotensive or syncopal episodes. Caution is also advised in patients who are dehydrated (e.g., due to severe or prolonged diarrhea or vomiting), since they may be more sensitive to the hypotensive effect of the drugs. Therapy should be initiated with the lowest dosage possible and titrated gradually based on patient response and tolerance in accordance with the individual product package labeling. During initiation or reinstitution of therapy and following an increase in dosage, patients should be advised not to rise abruptly from a sitting or recumbent position and to avoid situations where injury could result if syncope occur. Concomitant use of alcohol, extensive periods of standing, prolonged or intense exercise, and exposure to heat can also precipitate orthostatic hypotension and should be minimized. If dizziness, lightheadedness or palpitations occur, the patient should sit or lie down, and seek medical attention if symptoms are recurrent or bothersome.

  16 sources

  1. Grunstein JA "The problem of postural hypotension." Gerontol Clin (Basel) 16 (1974): 171-4
  2. Glass AR, Ballou R "Pheochromocytoma, prazosin, and hypotension." Ann Intern Med 97 (1982): 455
  3. Melkild A "Prazosin (peripress): a long-term study." Curr Med Res Opin 9 (1984): 219-28
  4. Graham RM, Thornell IR, Gain JM, Bagnoli C, Oates HF, Stokes GS "Prazosin: the first-dose phenomenon." Br Med J 2 (1976): 1293-4
  5. "Prazosin (Minipress) for hypertension." Med Lett Drugs Ther 19 (1977): 1-2
  6. Salim SS, Mtui EP, Makene WJ "An open evaluation of the efficacy and toleration of prazosin in patients with hypertension." East Afr Med J 54 (1977): 429-33
  7. "Product Information. Cardura (doxazosin)." Pfizer U.S. Pharmaceuticals (2001):
  8. "Product Information. Hytrin (terazosin)." Abbott Pharmaceutical (2001):

  Show all 16 sourcesShow fewer sources

  9. Troffa C, Manunta P, Dessifulgheri P, Pazzola A, Sabino G, Patteri G, Tonolo G, Pupita G, Glorioso N, Gitti M, Rappelli A "Efficacy and tolerability of doxazosin alone or in combination with chlorthalidone in essential hypertension." Curr Ther Res Clin Exp 55 (1994): 22-31
  10. Ahaneku JE, Taylor OG, Walker D, Agbedana OE, Salako LA "Blood pressure and biochemical changes during doxazosin monotherapy in nigerian hypertensive patients." Curr Ther Res Clin Exp 55 (1994): 1067-74
  11. Takata Y, Yoshizumi T, Ito Y, Hirota Y, Fujishima M "Effect of administration and withdrawal of doxazosin on ambulatory blood pressure in patients with essential hypertension." Angiology 46 (1995): 11-8
  12. Limbird LE eds., Gilman AG, Hardman JG "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: McGraw-Hill (1995):
  13. Roehrborn CG, Siegel RL "Safety and efficacy of doxazosin in benign prostatic hyperplasia: a pooled analysis of three double-blind, placebo-controlled studies." Urology 48 (1996): 406-15
  14. "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim (2001):
  15. "Product Information. Uroxatral (alfuzosin)." sanofi-aventis (2003):
  16. "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals (2008):

• Kidney Failure, Chronic

  Moderate

  Patients with renal impairment do not require an adjustment in tamsulosin dosing. However, patients with end-stage renal disease (Clcr <10 mL/min) have not been studied.

  1 source

  1. "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim (2001):

• Liver Diseases

  Moderate

  Finasteride and dutasteride are extensively metabolized by the liver. Therapy with these drugs should be administered cautiously in patients with liver disease as exposure could be higher.

  2 sources

  1. "Product Information. Proscar (finasteride)." Merck & Co., Inc (2002):
  2. "Product Information. Duagen (dutasteride)." GlaxoSmithKline Healthcare (2002):

• Liver Failure

  Moderate

  Patients with moderate hepatic impairment do not require any adjustment in tamsulosin dosage. Tamsulosin has not been studied in patients with severe hepatic impairment.

  1 source

  1. "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim (2001):