Digitalis INDEX

Because digitoxin has a very low therapeutic index, toxicity occurs rather routinely and can be fatal patients must be monitored closely. Moderate overdoses can be picked up by GI or CNS complaints however, more serious toxicity on cardiac rhythm is more difficult to distinguish from the effects of heart disease. Digitalis antibody fragments are available for serious toxicity, i.e., when cardiac arrest is imminent. The fragments bind the drug and are excreted by the kidneys. 

If we consider the mode of action of digitalis, what would we expect the therapeutic index of the dmg to be Large or rather smaller Complete receptor saturation will completely knock out the NaVK -ATP ase and thereby terminate the life of the target cell. Thus, it is quite obvious that we will have to walk a fine line in determining the right dosage. Therefore, we will have to consider very carefully the pharmacokinetic properties of the dmgs, and the kidney and/or liver functions of the patient. 

Other inotropic drugs are necessary not to replace digitalis as much as to supplement in cases of severe heart failure refractory to the glycosides, and in situations where their efficacy is insufficient and the therapeutic index is too low. The clinical goal is to improve the symptoms of cardiac failure by improving left ventricular function or by reducing resistance to the heart s output against the peripheral circulation—or even better—to achieve both. 

In another retrospective population-based case-control study, data from the National Health Insurance Research Database were scrutinized in a search for patients with heart failure newly treated with digoxin between January 2001 and December 2004 who were hospitalized for digitalis toxicity they were compared with the matched controls for use of clarithromycin [5 ]. Prescription of clarithromycin before the index date was associated with increased risk of hospitalization for digoxin intoxication the relative risks were 4.36 at 7 days (95% Cl = 1.28,15), 5.07 at 14 days (95% Cl = 2.36, 11), and 2.98 at 30 days (95% Cl = 1.59, 5.63). The effect was dose related. 

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