DRUGS for HEART FAILURE

  DIGITALIS

Digitalis was originally known as the foxglove, on account of the shape of the flowers of the plant. It has had a long history of medical use - having been listed among the herbs used by King Edward III (1327-77). It was given its Latin name - digitalis purpuses - by the German botonist, Leonard Fuchs, in 1542(1).

Digitalis was first used to treat dropsy in the 16th century by Rembert Dudoens, a Dutch doctor(2), but he was ignored, and although, by 1661, digitalis was being used as a treatment for epilesy and as a sedative(3), digitalis was not again mentioned as a treatment for dropsy until 1776, when a medical botonist, William Withering heard about its use. From his clinical studies, Withering concluded that digitalis had some kind of power over the heart(4). Although John Ferrier, in 1799, suggested that the action of digitalis on the pulse rate was more important than increased urinary output, and Thomas Beddowes wrote that digitalis could increase the contractions of the heart muscle fibres, both were to recoomend use of digitalis for pulmonary tuberculosis. Periera stated in his `Elements of Materia Medica and Therapeutics`, in 1855, that theprinciple value of digitalis lay in the treatment of dropsy, without mentioning that this should be of cardiac origin; and Potterin his `Materia Medica and Pharmacy` recommended digitalis as an aphrodisiac(5).

Extensive studies were conducted as to the action of digitalis on the hearts of amphibians and mammals(6) but in 1908, Sir James Mackenzie wrote in the `British Medical Journal` "On the action of digitalis in cardiac disease, the results of animal experiments must be accepted with caution"(7). Obviously giving no credit to animal experiments, Mackenzie used digitalis in clincial cases and reported in 1911 that through these studies of patients with rapid, irregular heart and pulse rates, digitalis could lower the heart rate(8). Following his clinically successful treatment of patients with digitalis, Mackenzie commented "the action of a drug [ie digitalis] on a healthy animal may have different reaction upon an individual affected by the disease... While by means of chemical testing and by experiment upon living animals, the potential of a remedy be accurately measured, it is a totally different matter to measure the susceptibility of the patient to the remedy"(9). Experimental work was also undertaken in London by Arthur Cushny, who included his findings in his book in 1925(10). Meanwhile, in 1908, the `British Medical Journal` commented "Prof Cushny said tht the difficulty of the subject was very great; even in experimental work, with the same dose of digitalis, given in the same way to the same animal, results varied widely from time to time"(11).

In 1943,  Andrew Neil recalled in `Medical World` "Animal experimenters found, as a result of experimentation on animals, that digitalis raised the blood pressure and, as a consequence, it was not used for some years on human beings. The fact that BP [blood pressure] is raised by digitalis was found - clinically - to incorrect in the case of human beings, and it is now freely used in cases in which laboratory experimenters `warned` us it would be dangerous"(12).

refs

1. Sneader,W. drug Discovery. John Wiley & Sons. 1985.

2. Silverman,M. Magic in the Bottle. Macmillan. 1948.

3. Marks,G. beatty,WK. The Medical Garden. Charles Scriber & Sons. 1971.

4. Withering,W. An Account of the Foxglove & Some of its Medicinal Uses. 1785.

5. Sneader,W. Drug Discovery. John Wiley & Sons. 1985.

6. Lewis,T. Clinical Science. Shaw & Son. 1934.

7. Mackenzie,J. British Medical Journal. 4 Jan 1908.

8. Lewis,T. Clinical Science. Shaw & Son. 1934.

9. Mackenzie,J. Diseases of the Heart. 4th ed. Oxford Uni Press. 1925. 

10. Cushny,AR. Action & Use in Medicine of Digitalis. Longmans. 1925.

11. British Medical Journal. 4 Jan 1908.

12. McNeil,AS. Medical World. 5 Feb 1943.