III. Dosing

  1. Start 0.4 mg orally daily
  2. Maximum 0.8 mg/day

IV. Adverse Effects

  1. See Selective Alpha-1a Antagonist
  2. Rare Sulfa Allergy cross-reactivity
  3. Postural Hypotension (esp. when combined with Antihypertensives)
  4. Floppy Iris Syndrome
  5. Ejaculatory Dysfunction (class effect)

V. Drug Interactions

  1. Avoid all Selective Alpha-1a Antagonists with strong CYP3A4 inhibitors (e.g. Ketoconazole, Clarithromycin, Itraconazole, Ritonavir)
  2. Avoid Tamsulosin with strong CYP2D6 Inhibitors (e.g. Fluoxetine)

VII. References

  1. Hamilton (2020) Tarascon Pharmacopoeia, Jones and Bartlett, Boston
  2. Nachawati (2022) Alpha Blockers, StatPearls, Treasure Island, FL, accessed 12/25/2022
    1. https://www.ncbi.nlm.nih.gov/books/NBK556066/

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Related Studies

Cost: Medications

tamsulosin (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
TAMSULOSIN HCL 0.4 MG CAPSULE Generic $0.06 each

Ontology: tamsulosin (C0257343)

Definition (NCI_NCI-GLOSS) A drug used to treat urinary problems caused by an enlarged prostate. Tamsulosin relaxes the muscles of the prostate and bladder, which helps the flow of urine. It is a type of alpha blocker.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C088482
SnomedCT 108559004, 372509005
LNC LP171642-4
English 5-(2-((2-(2-ethoxyphenoxy)ethyl)amino)propyl)-2-methoxybenzenesulfonamide, tamsulosin, 5-((2R)-2-(2-(2-ethoxyphenoxy)ethylamino)propyl)-2-methoxy-benzenesulfonamide, tamsulosin [Chemical/Ingredient], TAMSULOSIN, Tamsulosin, Tamsulosin (product), Tamsulosin (substance)
Spanish tamsulosina (producto), tamsulosina (sustancia), tamsulosina

Ontology: Flomax (C0662903)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C088482
English Flomax, Abbott laboratories brand of tamsulosin hydrochloride, flomax