Cardiac glycosides preparations

The cardiac glycoside preparations that have been used range from powdered digitalis leaf to... 

All cardiac glycosides preparations have the potential to cause toxicity. Because the minimal toxic dose of the glycosides is only two- to threefold the therapeutic dose, intoxication is quite common. In mild to moderate toxicity, the common symptoms are anorexia, nausea and vomiting, muscular weakness, bradycardia, and ventricular premature contractions. The nausea is a result of excitation of the chemoreceptor trigger zone in the medulla. In severe toxicity, the common symptoms are blurred vision, disorientation, diarrhea, ventricular tachycardia, and AV block, which may progress into ventricular fibrillation. It generally is accepted that the toxicity of the cardiac glycosides results from inhibition of the Na /K -ATPase pump, which results in increased intracellular levels of Ca ". Hypokalemia (decreased potassium), which can be induced by coadministration of... 

Cyclic carbonic esters were also prepared, for example, from the cardiac glycoside proscillaridine[257] (where besides CDI the benzyloxycarbonylimidazole was successfully used), ingenol, 2581 the macrolide antibiotic tylosine,[259] and an erythromycin A derivative.12601... 

The net result of the action of therapeutic concentrations of a cardiac glycoside is a distinctive increase in cardiac contractility (Figure 13-5, bottom trace). In isolated myocardial preparations, the rate of development of tension and of relaxation are both increased, with little or no change in time to peak tension. This effect occurs in both normal and failing myocardium, but in the intact patient the responses are modified by cardiovascular reflexes and the pathophysiology of heart failure. 

Crude leaf preparations of Digitalis have been in medical use since 1785. Pure cardiac glycosides are now available. These preparations in injectable tinctures or powdered leaf tablets are used extensively for the treatment of congestive heart failure. They increase the force of the heart muscle and the power of systolic contraction, apparently by inhibiting the active transport of K and Na ions through cell membranes. 

In recent years the chemistry of 2-desoxysugars generally, has been considerably broadened. In particular, new methods of synthesis have been developed for the preparation of many of the didesoxysugars known as the 2-desoxyhexomethyloses which occur naturally as components of the cardiac glycosides. The formation, structure, and stability of various 0- and iV-glycosides of sugars of this class have been examined in... 

Using the various methods described for the preparation of 2-desoxy-sugars, Reichstein and his colleagues have synthesized the 2-desoxyhexo-methyloses and 3-methyl-2-desoxyhexomethyloses which occur naturally as carbohydrate components of the cardiac glycosides. The present account refers briefly only to those researches reported since 1945 (see ref. 1). 

Multiple ingredients in product (the presence of a cardiac glycoside has been found in Chinese herbal preparation)... 

A number of reports of the characterization of the structure of impurities contained in pharmaceutical preparations also appeared in 1999 beginning with the isolation and characterization of two biologically active isomers of the cardiac glycoside dihydroouabain isolated from a commercial preparation.102... 

D-Digitoxose, a component of cardiac glycosides found in Digitalis purpurea and other higher plants, can be prepared following a similar method starting from ethyl (7 )-lactate and (7 )-HYTRA [83] (Scheme 13.41). 

K)-108 is isolated in 42% overall yield and > 99% ee. This compound has been converted into 109 by iodolactonization. It is a precursor of all kinds of 2-deoxyfuranosides [246], D-Digitoxose, a component of cardiac glycosides found in Digitalis purpurea and other higher plants, can be prepared following a similar method starting from ethyl (i )-lactate (111) and (i )-HYTRA (O Scheme 50) [247],... 

Legal reagent Solution I—0,5% of a recently prepared sodium nitroprussiate in water solution II—0.2 TV NaOH. Dissolve 2 mg of sample into pyndine (two to three drops), add one drop solution I, and four drops solution II (one at a time). A deep red color will be observed for cardiac glycosides and pink for a,p-unsatur-ated lactones and some p-,Y-lactones. (These should be kept under controlled pH since they may isomerize in alkaline solution.)... 

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