Digitalis toxicity.

There is a narrow margin between therapeutic and toxic doses and serum levels of digitalis glycosides. Clinicians should therefore be knowledgeable and attentive to early signs and symptoms of toxicity in order to optimize the risk:benefit ratio when using this class of drugs. A number of pharmacokinetic interactions with specific implications for digitalis toxicity have recently been delineated. Serious cardiac rhythm disturbances should initially be treated with lidocaine or phenytoin. Digitalis toxicity resistant to conventional measures may now be treated with digoxin-specific Fab fragments.