Glycosides toxicity

Lldoc ine. Lidocaine hydrochloride, an anilide, was originally introduced as a local anesthetic in 1943 and found to be a potent antiarrhythmic in 1960. The compound is a reverse amide of procainamide. Lidocaine is generally considered to be the dmg of choice in the treatment of ventricular arrhythmias and those originating from digitalis glycoside toxicity (1,2,15—17). 

The answer is b. (Hardman, pp 703-704J Low K stores due to the effects of thiazide diuretics such as hydrochlorothiazide increase susceptibility to cardiac glycoside toxicity... 

I will extend this argument to encompass the diversification of such systems in lineages of plants in an effort to correlate enzyme-mediated glycoside toxicity with the evolution of host plant specificity and the coevolution of plants and insects. 

Magnesium sulfate Sustained ventricular arrhythmias Torsades de pointes of magnesium depletion or glycoside toxicity... 

Wisteria sinensis (Sims) Sweet Zi Teng (Chinese wisteria) (seed, bark) Toxic glycosides, toxic resin.60 This herb is toxic. Diuretic. 

The most common cardiac manifestations of glycoside toxicity include atrioventricular junctional rhythm, premature ventricular depolarizations, bigeminal rhythm, and second-degree atrioventricular blockade. However, it is claimed that digitalis can cause virtually every variety of arrhythmia. 

The prevalence of digitalis intoxication is from 16% to 20%. Color vision disturbances are especially common and may occur before, simultaneously with, or after the onset of cardiac toxicity. Although color vision disturbances are associated with cardiac glycoside toxicity decreased visual acuity without the accompanying classic symptom of xanthopsia is also common. 

The electrocardiographic effects of cardiac glycoside toxicity in 688 patients have been reviewed in the context of three cases of digoxin toxicity (49). The three cases featured bidirectional tachycardia in a 50-year-old man with a plasma digoxin concentration of 3.7 ng/ml, junctional tachycardia in a 59-year-old man with a plasma digoxin concentration of 4.3 ng/ml, and complete heart block in a 90-year-old woman whose postmortem digoxin concentration was 5.0 ng/ml. 

Glycosides include digoxin (Lanoxin), inamrinone lactate (Inocor) and milrinone lactate (Primacor), and positive inotropic bipyridines. The antidote for glycoside toxicity is digoxin immune Fab (Ovine, Digibind). 

They antagonize the positive inotropic and chronotropic effects of catecholamines. Cardiac arrhythmias associated with excessive adrenergic stimulus, released endogenous catecholamines or sensitization of the heart by anes-thetics or cardiac glycosides may effectively be treated by 6-blockade. Some B-blockers also possess membrane or local anesthetic action and are effective against arrhythmias due to ischemia or cardiac glycoside toxicity as well. This membrane action was shown to be independent of 6-blockade since resolved isomers of B-blockers possessed equal antiarrhythmic potency but unequal B-blocking action. 

Dilantin reversal of cardiac glycoside toxicity was well documented. Woodbury has shown that dilantin augments the active transport of Na and K" " in the brain, skeletal and cardiac muscle. Its ability to reverse digitalis toxicity has been attributed to a direct action on Na,K-ATPase . 

Depending on the amount of amygdalin present and the manner in which food is prepared from plants containing cyanogenic glycosides, toxic levels of hydrogen cyanide can result. 

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