Ephedrine tachycardia caused

Sympathomimetic syndromes include tachycardia, hypertension, hyperthermia, sweating, mydriasis, hyperreflexia, agitation, delusions, paranoia, seizures and cardiac arrhythmias. These are commonly caused by amphetamine and its derivatives, cocaine, proprietary decongestants, e.g. ephedrine, and theophylline (in the latter case, excluding psychiatric effects). 

An article in the Canadian Adverse Reaction Newsletter published their reporting of adverse effects caused by products containing C. aurantium from January 1, 1998 to February 28, 2004 (46). The article lists 16 reports of synephrine associated with cardiovascular events including tachycardia, cardiac arrest, ventricular fibrillation, transient collapse, and blackout. In one case, bitter orange was the sole suspected culprit. In seven others the products also contained caffeine, and in eight cases the product contained both caffeine and ephedrine. Health Canada has issued an advisory stating that synephrine may have effects similar to ephedrine and caution should be used if taking it (47). 

Alkalinisation of the urine (e.g. by sodium bicarbonate) causes retention of ephedrine and pseudoephedrine by the kidneys, leading to the possible development of toxicity (tremors, anxiety, insomnia, tachycardia). Acidification of the urine (e.g. with ammonium chloride) has the opposite effect. 

Ephedrine is a sympathomimetic or central nervous system stimulant. It is a potent stimulator of a, pi and p2 adrenergic receptors. The effects include vasoconstriction, raised blood pressure and pulse, bronchodilation and diuresis. Ephedrine-based drugs are used as nasal decongestants, bronchodilators and in anaphylactic shock. In excess they cause insomnia, tachycardia and dizziness. 

By the mechanisms mentioned above, it is possible to correlate the clinical effects observed with the use of ephedrine, as well as to establish the possible effects before the consumption. The use of ephedrine in therapeutic doses raises the blood pressure by increasing cardiac output and also by inducing peripheral vasoconstriction. It may cause tachycardia. Its action on p- adrenergic receptors in the heart produces a positive ionotropic effect. Ephedrine has a stimulant action on the respiratory center. It also causes bronchodilatation, reduces intestinal tone and motility, and usually reduces the activity of the uterus. Its effects on a-adrenergic receptors results in vasoconstriction in the skin and mucous membranes [12], leading to hypertension, which may produce cerebral hemorrhage and pulmonary edema. 

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