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guanethidine (Ismelin, Santensin)
Tradename: Ismelin.
Indication: treatment of moderate to severe hypertension
Contraindications:
1) pheochromocytoma
2) concurrent administration of MAO inhibitor
Caution:
1) use with caution in the elderly
2) frequent occurrence of orthostatic hypotension
Dosage:
1) adults
a) start 10 mg PO QD
b) increase by 10 mg/day at intervals of 5-7 days
c) usual 25-50 mg/day
2) children
a) start: 0.2 mg/kg/day up to 10 mg
b) increase by 0.2 mg/kg every 1-3 weeks
c) maximum dose: 3 mg/kg/day
Tabs: 10 & 25 mg.
Adverse effects:
1) common (> 10%)
- palpitations, chest pain, peripheral edema, fatigue, headache, faintness, drowsiness, confusion, increased bowel movements, pain from flatulence, constipation, anorexia, weight gain/loss, nocturia, polyuria, retrograde ejaculation, paresthesia, muscle ache (especially leg cramps), backache, arthralgia, visual disturbances, shortness of breath, cough
2) less common (1-10%)
- orthostatic hypotension, psychologic disturbance, depression, sleep disorder, glossitis, nausea/vomiting xerostomia, hematuria
3) uncommon (< 1%)
- syncope, angina
4) other
- fluid retention
- diarrhea
Drug interactions:
1) tricyclic antidepressants (TCA), antihistamines, ephedrine interfere with the action of guanethidine
2) phenothiazines
3) anorexiants
4) haloperidol
5) maprotiline
6) methylphenidate
7) MAO inhibitors
Mechanism of action:
- replaces norepinephrine within secretory granules of adrenergic neurons
Interactions
drug interactions
drug adverse effects of antihypertensive agents
General
adrenergic neuron inhibitor
Properties
MISC-INFO: elimination route LIVER
KIDNEY
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, pg 790
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 474
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
Component-of
guanethidine/hydrochlorothiazide; guanethidine/HCTZ (Esmil)