Guanethidine Ephedrine

Other conditions in which ephedra is contraindicated are anxiety disorders, angle-closure glaucoma, prostate adenoma with residual urine volume, pheochromocytoma, and thyrotoxicosis (Gruenwald et al. 1998). Known medications that may interact adversely with ephedrine include heart glycosides, halothane, guanethidine, MAO inhibitors, secale alkaloids, and oxytocin. 

Ephedrine may negate the antihypertensive effects of guanethidine and may potentiate the pressor effects of MAO inhibitors causing hypertensive crisis and intracranial hemorrhage. 

Clinically important, potentially hazardous interactions with alcohol, amiodarone, beta-blockers, cimetidine, donidine, digoxin, diltiazem, disopyramide, ephedrine, epinephrine, ergot alkaloids, guanethidine, halothane, isoprenaline, lidocaine, noradrenaline, NSAIDs, phenylephrine, quinidine, reserpine, verapamil... 

Cyclobenzaprine Decongestants (topical and systemic) Dextromethorphan Dopamine Ephedrine Epinephrine Guanethidine... 

The antihypertensive effects of guanethidine can be reduced or abolished by drugs including dexamfetamine, ephedrine, metam-fetamine and methylphenidate. The blood pressure may even rise higher than before treatment with the antihypertensive. 

When 16 hypertensive patients taking guanethidine 25 to 35 mg daily were given single-doses of dexamfetamine 10 mg orally, ephedrine 90 mg orally, metamfetamine 30 mg intramuseularly or methylphenidate 20 mg orally, the hypotensive efifeets of the guanethidine were eom-... 

D-amphetamine, methamphetamine, ephedrine, phenylephrine, phenteramine, mephenteramine, methylphenidate and diethylpropion all work antagonistically by displacing guanethidine from the binding site. In addition to this the combination with any of these substances carries an increased risk of cardiac arrhythmia (3, 7", 12 , 13, 26 ). 

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