tamsulosin (Flomax, Urolosin)
Jump to navigation
Jump to search
Introduction
Tradename: Flomax. FDA-approved generic March 3, 2010
Indications
- benign prostatic hypertrophy
- easing passage of urinary calculus[6]
Contraindications
- concurrent use of other alpha-adrenergic antagonists
Dosage
start 0.4 mg PO QHS; maximum 0.8 mg QHS
Capsules: 0.4 mg, 0.8 mg (Do Not crush) {NOT suitable for G-tube}
No dosage adjustment with renal insufficiency.
Pharmacokinetics
- > 90% absorption of oral dose (fasting)
- maximum serum concentration reached 4-5 hours after oral dose (fasting)
- food somewhat impairs & delays absorption (30%)
- 90-94% bound to serum protein, primarily alpha-1 acid glycoprotein
- extensively metabolized by cytochrome P450
- metabolites conjugated prior to elimination in the urine (76%)
- 21% eliminated in the feces
- < 10% excreted unchanged in the urine
- linear elimination kinetics
- t1/2 9-15 hours
- steady-state concentrations reached after 5th day of QD dosing
- maximal response for BPH in 1-2 weeks
- clinical improvement may be seen in 8 hours
elimination via liver
protein binding = 95 %
elimination by hemodialysis = -
1/2life = 9-15 hours
Adverse effects
- orthostatic hypotension* (0.2-0.4%)
- 2 fold risk of severe hypotension
- risk especially high early in treatment[10]
- up to 8 weeks into treatment
- restarting tamsulosin also associated with risk of severe hypotension[10]
- somnolence
- insomnia
- rhinitis
- retrograde ejaculation#
- dizziness
- cough
- sinusitis
- asthenia
- back pain
- chest pain
- amblyopia
- Intraoperative Floppy Iris Syndrome (IFIS) during phacoemulsification cataract surgery[7][8]
- do not initiate tamsulosin therapy prior to scheduled cataract surgery[11]
* least likely to cause orthostatic hypotension among alpha-1 blockers[5]
# most common among alpha-1 blockers used for BPH
- drug adverse effects of alpha-1 adrenergic receptor antagonists
- drug adverse effects of antihypertensive agents
Drug interactions
- other alpha-adrenergic receptor antagonists
- cimetidine diminishes clearance of tamsulosin
- studies of interaction with warfarin are inconclusive Test interaction:
- none known
- no effect on PSA
- drug interaction(s) of phosphodiesterase-5-inhibitors with alpha-1-adrenergic receptor antagonists
- drug interaction(s) of loop diuretics with alpha-1 adrenergic receptor antagonist
- drug interaction(s) of NSAIDs & antihypertensives
Mechanism of action
- alpha-1A adrenergic receptor antagonist[3]
- 70% of alpha-1 receptors in the prostate are alpha-1A receptors
- relaxation of smooth muscle in the neck of the bladder & prostate
- NOT an anti-hypertensive agent[3]
More general terms
Additional terms
Component of
References
- ↑ www.flomax.bph.com
- ↑ Physician's Desk Reference (PDR) 54th edition, Medical Economics, 2000
- ↑ 3.0 3.1 3.2 Aronson W. in: UCLA Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001
- ↑ Geriatric Dosage Handbook, 6th edition, Selma et al eds, Lexi-Comp, Cleveland, 2001
- ↑ 5.0 5.1 Prescriber's Letter 10(9):53 2003
- ↑ 6.0 6.1 Prescriber's Letter 11(9): 2004 Use of Nifedipine or Tamsulosin for Kidney Stones Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=200911&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ 7.0 7.1 FDA Medwatch http://www.fda.gov/medwatch/safety/2005/safety05.htm#Flomax
- ↑ 8.0 8.1 Bell CM et al Association Between Tamsulosin and Serious Ophthalmic Adverse Events in Older Men Following Cataract Surgery JAMA. 2009;301(19):1991-1996. <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/19454637 <Internet> http://jama.ama-assn.org/cgi/content/full/301/19/1991
Friedman AH Tamsulosin and the Intraoperative Floppy Iris Syndrome JAMA. 2009;301(19):2044-2045. <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/19454645 <Internet> http://jama.ama-assn.org/cgi/content/extract/301/19/2044 - ↑ FDA NEWS RELEASE: March 2, 2010 FDA Approves First Generic Tamsulosin to Treat Enlarged Prostate Gland http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm202728.htm
- ↑ 10.0 10.1 10.2 Bird ST et al Tamsulosin treatment for benign prostatic hyperplasia and risk of severe hypotension in men aged 40-85 years in the United States: risk window analyses using between and within patient methodology. BMJ 2013;347:f6320 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/24192967 <Internet> http://www.bmj.com/content/347/bmj.f6320
- ↑ 11.0 11.1 Geriatric Review Syllabus, 9th edition (GRS9) Medinal-Walpole A, Pacala JT, Porter JF (eds) American Geriatrics Society, 2016