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terazosin (Hytrin, Hydracin, Hytrinex, Vasocard)
Tradename: Hytrin.
Indications:
- hypertension
- benign prostatic hypertrophy (BPH)
- adjunctive agent in the management of congestive heart failure (CHF)
- urinary calculus [6]
Dosage:
1) start 1 mg PO QHS, max 20 mg/day
2) give 1st dose QHS (1st dose syncope)
3) do NOT withdraw therapy abruptly; taper dose
Tabs: 1, 2, 5, 10 mg.
Caution:
- QHS dosing; postural hypotension & syncope may occur with the 1st dose
Pharmacokinetics:
1) oral bioavailability is 90%
2) 90-94% bound to plasma proteins
3) extensively metabolized in the liver
4) excreted in feces & urine
5) onset of action is within 15 minutes
6) peak effects are seen in 2 hours
7) duration of action 24 hours
8) elimination 1/2life is 13 hours
9) pharmacokinetics are not altered by uremia, CHF or aging
10) maximal response for BPH is 4-6 weeks
Adverse effects:
1) common (> 10%)
- orthostatic hypotension, dizziness, lightheadedness, headache, malaise
2) less common (1-10%)
- edema, palpitations, urinary incontinence, dry mouth, fatigue, nervousness
3) uncommon (< 1%)
- angina, dyspnea, priapism, nausea, urinary frequency, nasal congestion, nightmares, rash, sexual dysfunction, hypothermia
4) other
- 1st dose syncope
- fatigue
- drowsiness
Drug interactions:
1) beta blockers enhance postural hypotension reactions
2) clonidine: decreased antihypertensive effect
Laboratory:
- terazosin in blood
- terazosin in serum/plasma
Mechanism of action:
1) alpha-1 adrenergic receptor antagonist
2) reduces total peripheral resistance through both arterial & venous dilation
3) little or no change in heart rate or cardiac output
4) increases urine flow in BPH by relaxing smooth muscle tone in the bladder neck of the prostate
5) relaxes internal urethral sphincter [5]
6) increases HDL cholesterol
7) enhances glycolysis [7]
- may improve glucose tolerance with long-term therapy
8) may lower risk of Parkinson's disease (RR=0.88) [7]
9) may reduce left ventricular hypertrophy with long-term therapy
Interactions
drug interactions
drug adverse effects (more general classes)
General
alpha-1 adrenergic receptor antagonist; prostate-selective alpha blocker
piperazinyl quinazoline
Properties
MISC-INFO: elimination route LIVER
KIDNEY
protein-binding 90-94%
1/2life 13 HOURS
pregnancy-category C
safety in lactation ?
Database Correlations
PUBCHEM correlations
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Geriatrics Review Syllabus, American Geriatrics Society,
5th edition, 2002-2004
- Deprecated Reference
- Simmering JE, Welsh MJ, Liu L et al
Association of Glycolysis-Enhancing alpha-1 Blockers With Risk
of Developing Parkinson Disease.
JAMA Neurol. 2021;78(4):407-413. Feb 1.
PMID: 33523098 PMCID: PMC7851758 Free PMC article
https://jamanetwork.com/journals/jamaneurology/fullarticle/2775976