This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
The dried leaves of Digitalis purpurea. Digitalis contains a number of glucosidal principles, the most important of which are digitoxin, digitalin and digitalein, the actions of which are essentially similar. A number of preparations of these glucosids are on the market, but many are of uncertain composition, and since they have not yet demonstrated any superiority over good preparations of the whole drug, the latter are to be preferred. Digitalis is a fairly stable drug, and those preparations that are made with high percentages of alcohol retain their full activity with little alteration for several years. Aqueous solutions deteriorate very rapidly.
Action and Uses: Digitalis, either in substance, or as one of the preparations referred to hereafter, is a cardiac tonic and diuretic. (See the preceding.)
Digitalis is useful whenever the systole of the heart is insufficient on account of incomplete exertion of its muscular power. It causes the heart to empty itself more completely and prevents it from dilating excessively during diastole. It is useful in decompensated valvular disease, in dropsy from weak heart-action and in constantly irregular pulse, which is due to fibrillation of the auricle.
Dosage: 0.065 gm. or 1 grain, in powder or pill. Digitalis is a drug of variable strength, and hence a physiologically standardized preparation should be used. No perceptible effect is to be expected in less than twenty-four hours after oral administration. A slowing of the pulse indicates the beginning of its physiologic action; nausea and vomiting coming on during the administration of the drug are usually due to a commencing toxic action. If the vomiting is due to other causes, the administration of the digitalis may be continued best by a different channel, such as the rectum or the veins, or by hypodermic injection. For hypodermic and intravenous injections special preparations must be used, for which N. N. R. should be consulted.
Overdosage: As an overdose of digitalis or cumulative effects are most readily detected by a study of the pulse and heart-action, a patient who has been given digitalis should be kept under close observation. As a rule, the conditions which require digitalis also require that the patient stay in bed.
Symptoms of digitalis poisoning are shown by nausea and vomiting, sometimes great gastro-intestinal irritation, with pain and diarrhea, a very slow pulse, followed by a rapid and feeble one, or heart-block and marked prostration. The heart may become irregular and sudden changes in position may result in great aggravation of the condition and sometimes in sudden death. On the occurrence of any of these symptoms, the administration should be suspended.
Aside from its use in powder or pills, digitalis is used largely as:
One hundred c.c. represent the water-soluble constituents of 1.5 gm digitalis partially preserved by alcohol (10 per cent.). It should be freshly prepared.
Dosage: 8 c.c. or 2 fluidrams.
One hundred c.c. represent 10 gm. digitalis in diluted alcohol.
Dosage: 1 C.c. Or 15 Minims.
See Serum Antidiphthericum.