Alpha Adrenergic Antagonist

Aka: Alpha Adrenergic Antagonist, Selective Alpha-1a Antagonist, Prazosin, Minipress, Terazosin, Hytrin, Doxazosin, Cardura, Tamsulosin, Flomax, Alfuzosin, Uroxatral, Silodosin, Rapaflo

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II. Indications

  1. Benign Prostatic Hypertrophy
  2. Hypertension (not Tamsulosin)

III. Mechanism: General

  1. See Alpha Adrenergic Receptor (Alpha-1 antagonist)

IV. Mechanism: Benign Prostatic Hypertrophy

  1. Preparations used in Benign Prostatic Hypertrophy
    1. Terazosin (Hytrin)
    2. Doxazosin (Cardura)
    3. Tamsulosin (Flomax)
    4. Prazosin (Minipress)
  2. Rapid relaxation of smooth muscle tone
    1. Bladder neck
    2. Prostate Capsule
    3. Prostatic Urethra
  3. Relieves symptoms of urinary obstruction
    1. May see full effect within 2 weeks
  4. Does not effect size of Prostate (unlike Proscar)

V. Preparations: Non-Selective Agents

  1. Prazosin (Minipress)
    1. Dose: 1 mg PO bid-tid (Maximum 40 mg/day)
    2. Less expensive but not available for once daily dose
  2. Terazosin (Hytrin)
    1. Dose: 1 mg PO qhs (Maximum 20 mg/day)
  3. Doxazosin (Cardura)
    1. Dose: 1 mg PO qd (Maximum 16 mg/day)
  4. Phenoxybenzamine (Dibenzyline)
    1. Dose: 10 mg PO bid (Maximum 120 mg/day)

VI. Preparations: Selective Alpha-1a Antagonists (Prostate specific agents)

  1. Precautions
    1. Still cause Orthostatic Hypotension, fall risk, Head Trauma and Fractures, despite selective nature
    2. Number needed to harm (NNH): 600 for fall-related hospitalizations, and 1600 for fall-related Fractures
    3. Welk (2015) BMJ 351:h5398 +PMID:26502947 [PubMed]
  2. Alfuzosin (Uroxatral, generic)
    1. Dose: 10 mg once daily
    2. Contraindicated in moderate to severe liver disease (and Exercise caution in renal disease)
  3. Silodosin (Rapaflo)
    1. Dose: 8 mg daily with food (4 mg daily if GFR 30-50 ml/min)
    2. Contraindicated when GFR <30 ml/min or severe liver disease (Child-Pugh Score 10 or more)
  4. Tamsulosin (Flomax, generic)
    1. Dose 0.4 mg orally daily (maximum 0.8 mg/day)

VII. Combination Alpha-Beta Antagonist (Labetalol or Trandate)

  1. Oral: 100 mg PO bid (Maximum: 2400 mg/day)
  2. Intravenous: 20 mg IV q10 minutes (Maximum: 200 mg)

VIII. Adverse effects (Incidence: 7 to 9%)

  1. Dose at bed and slowly titrate to reduce side effects
  2. Cardiovascular adverse effects (also occurs with selective agents, albeit less often)
    1. Dizziness
    2. Postural Hypotension
    3. Associated with fall risk and secondary Fracture risk
  3. Other adverse effects
    1. Fatigue
    2. Asthenia

IX. Precautions

  1. Avoid using as monotherapy for Hypertension
    1. Higher risk of CVA and CHF compared with other agents
    2. (2000) JAMA 283:1967-75 [PubMed]

X. References

  1. Aldridge (1996) Lancet 348:602
    1. http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(05)64801-5/abstract
  2. (1994) Med Lett Drugs Ther 36: 15 [PubMed]
  3. (1997) Med Lett Drugs Ther 39: 1011 [PubMed]
  4. Lee (2000) Ann Pharmacother 34:188-99 [PubMed]

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Related Studies

Cost: Medications

Terazosin (on 6/18/2017 at Walmart.com)
Terazosin 10mg #30 capsules for $4.00 $0.13 each
Terazosin 10mg #90 capsules for $10.00 $0.11 each
Terazosin 1mg #30 capsules for $4.00 $0.13 each
Terazosin 1mg #90 capsules for $10.00 $0.11 each
Terazosin 2mg #30 capsules for $4.00 $0.13 each
Terazosin 2mg #90 capsules for $10.00 $0.11 each
Terazosin 5mg #30 capsules for $4.00 $0.13 each
Terazosin 5mg #90 capsules for $10.00 $0.11 each
prazosin (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
PRAZOSIN 1 MG CAPSULE Generic $0.42 each
PRAZOSIN 2 MG CAPSULE Generic $0.67 each
PRAZOSIN 5 MG CAPSULE Generic $1.04 each
terazosin (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
TERAZOSIN 1 MG CAPSULE Generic $0.06 each
TERAZOSIN 10 MG CAPSULE Generic $0.06 each
TERAZOSIN 2 MG CAPSULE Generic $0.06 each
TERAZOSIN 5 MG CAPSULE Generic $0.06 each
doxazosin (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
DOXAZOSIN MESYLATE 1 MG TAB Generic $0.29 each
DOXAZOSIN MESYLATE 2 MG TAB Generic $0.26 each
DOXAZOSIN MESYLATE 4 MG TAB Generic $0.28 each
DOXAZOSIN MESYLATE 8 MG TAB Generic $0.27 each
cardura (on 6/1/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
CARDURA 2 MG TABLET Generic $0.26 each
CARDURA 4 MG TABLET Generic $0.28 each
CARDURA XL 4 MG TABLET $4.69 each
tamsulosin (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
TAMSULOSIN HCL 0.4 MG CAPSULE Generic $0.14 each
flomax (on 1/4/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
FLOMAX 0.4 MG CAPSULE Generic $0.14 each
alfuzosin (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
ALFUZOSIN HCL ER 10 MG TABLET Generic $0.17 each
uroxatral (on 5/18/2016 at Medicaid.Gov Survey of pharmacy drug pricing)
UROXATRAL 10 MG TABLET Generic $0.17 each
rapaflo (on 2/22/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
RAPAFLO 4 MG CAPSULE $7.30 each
RAPAFLO 8 MG CAPSULE $7.29 each
FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information.

Ontology: Prazosin (C0032912)

Definition (MSH) A selective adrenergic alpha-1 antagonist used in the treatment of HEART FAILURE; HYPERTENSION; PHEOCHROMOCYTOMA; RAYNAUD DISEASE; PROSTATIC HYPERTROPHY; and URINARY RETENTION.
Definition (NCI) A synthetic piperazine derivative and an alpha-1 adrenergic receptor inhibitor used primarily as an anti-hypertensive. Prazosin's effects are most pronounced in the large resistance vessels (i.e. arterioles) and result in a decrease in total systemic vascular resistance (SVR) without a rebound or reflex tachycardia. To a lesser extent, this agent also decreases the tone of the bladder sphincter, thereby allowing the opening of the bladder into the urethra and thus relieving the urinary conditions associated with benign prostatic hypertrophy.
Definition (CSP) 1-(4-amino-6,7-dimethoxy- 2-quinazolinyl) -4-(2-furoyl) piperazine.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D011224
SnomedCT 367555002, 387283005, 387433003, 76058001, 51505001
LNC LP18588-1, MTHU004704
English Furazosin, Prazosin, Piperazine, 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-(2-furanylcarbonyl)-, 2-[4-(2-furoyl)piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline, 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-(2-furanylcarbonyl)piperazine, Prazosin [Chemical/Ingredient], PRAZOSIN, prazosin (medication), Furazosin (product), prazosin, Prazosin (product), Prazosin (substance), Furazosin (substance)
Swedish Prazosin
Czech prazosin
Finnish Pratsosiini
Russian PRAZOZIN, ADVERZUTEN, FURAZOZIN, PRATSIOL, АДВЕРЗУТЕН, ПРАЗОЗИН, ПРАТСИОЛ, ФУРАЗОЗИН
Japanese プラゾシン, 塩酸プラゾシン, フラゾシン
Italian Furazosina, Prazosina
Spanish prazosina (producto), prazosín (producto), furazosín, furazosina, furazosín (producto), furazosina (sustancia), prazosina (sustancia), prazosina, prazosín, Furazosina, Prazosina
Polish Prazosyna
French Prazosine
German Furazosin, Prazosin
Portuguese Furazosin, Prazosina
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Terazosin (C0076107)

Definition (NCI_NCI-GLOSS) A drug used to treat urinary problems caused by an enlarged prostate. It is also used to treat high blood pressure and is being studied in the treatment of other conditions. Terazosin relaxes muscle tissue in blood vessels and in the prostate. It is a type of alpha blocker.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C041226
SnomedCT 349914007, 129484001, 387068008
LNC LP101133-9, MTHU036183
English terazosin, Terazosin, Terazosin [Chemical/Ingredient], terazosine, TERAZOSIN, Terazosin (product), Terazosin (substance)
Spanish terazosina (producto), terazosina (sustancia), terazosina
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Doxazosin (C0114873)

Definition (MSH) A prazosin-related compound that is a selective alpha-1-adrenergic blocker.
Definition (NCI) A quinazoline with antihypertensive and antineoplastic properties. Doxazosin is an alpha-adrenergic antagonist that selectively inhibits alpha-1 adrenergic receptors. Blockages of the alpha-1 adrenergic action on the vascular smooth muscles lead to a decrease in vascular resistance and antihypertensive activity. This agent also shows high affinity to alpha-1c adrenoceptor, the predominant functional type in the prostate, which may partially attribute to its effect in treatment of benign prostatic hyperplasia. Furthermore, doxazosin induces apoptosis in prostate cancer cells mediated through inhibition of protein kinase B (PKB)/Akt-signaling death receptor regulatory pathway.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D017292
SnomedCT 108556006, 372508002
LNC LP171393-4
English Doxazosin, Piperazine, 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-((2,3-dihydro-1,4-benzodioxin-2-yl)carbonyl)-, Doxazosin [Chemical/Ingredient], doxazosin (medication), alpha blockers doxazosin, doxazosin, DOXAZOSIN, Doxazosin (product), Doxazosin (substance)
Swedish Doxazosin
Czech doxazosin
Finnish Doksatsosiini
Russian DOKSAZOZIN, ДОКСАЗОЗИН
Japanese ドキサゾシン, ドキサゾシンメシレート, メシル酸ドキサゾシン
Spanish Doxazosina, Doxazosin, doxazosina (producto), doxazosina (sustancia), doxazosina
Portuguese Doxazossina, Doxazosin, Doxazosina
Polish Doksazosyna, Metylosulfonian doksazosyny
French Doxazosine
German Doxazosin
Italian Dossazosina
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Minipress (C0242447)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D011224
English Pfizer Brand of Prazosin Hydrochloride, minipress, Minipress
Derived from the NIH UMLS (Unified Medical Language System)

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
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Hytrin (C0591628)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C041226
English Abbott Brand of Terazosin Hydrochloride, hytrin, hytrin bph, Hytrin, Hytrin BPH, Deflox, Flotrin, Heitrin, Hytrine
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Flomax (C0662903)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C088482
English Flomax, Abbott laboratories brand of tamsulosin hydrochloride, flomax
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Cardura (C0678136)

Definition (MSH) Trade name in United States.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D017292
English Carduran, cardura, carduran, Cardura, Cardular, Pfizer Brand of Doxazosin Mesylate, Zoxan
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Pharmacology

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