Tracing digitalis (and digitalis toxicity) back to an 18th century physician
Before 1785, treating shortness of breath or edema – diagnoses then described as “suffocative catarrh” and “dropsy”– typically involved purgatives, blistering, garlic, “medicinal” use of wine or ale, and draining fluid from the abdomen.
There was little sense of the heart’s role in these ailments, and the treatments tended to prove ineffective – until, that is, an English physician uncovered new medicinal purposes for a purple wildflower called Foxglove and the digitalis found within.
William Withering’s exploration of Foxglove
William Withering, pictured below with a Foxglove plant in hand, had the perfect combination of skills to discover its healing properties. Though a physician by trade, his wife (and former patient), Helena Cooke, was an artist who specialized in botanical arrangements. Her interest in botany sparked his own and led to the publication of his first and most successful book, with the catchy title, A Botanical Arrangement of All the Vegetables Naturally Growing in Great Britain with Descriptions of the Genera and Species According to Linnaeus.
It was only years later, during his travels to see patients in the countryside, that Withering discovered – from an old woman in Shropshire who had long kept the recipe secret – that an herbal tea made from Foxglove could be an effective treatment for dropsy. Later, he wrote a book about Foxglove and gestured towards digitalis’ effect on the heart. Withering found the plant to be most useful in treating patients with what we would know today as advanced heart failure or atrial fibrillation, and said digitalis had “a power over the motion of the heart to a degree yet unobserved in any other medicine and that this power may be converted to salutary ends.”
Though Withering was not the first to use Foxglove for medical purposes – it’s mentioned in writings as early as 1250 – his research proved foundational in the development of therapies related to the heart, including more recent discoveries of digoxin and other cardiac glycosides for atrial fibrillation still used today.
Understanding the limits – and side effects – of digitalis
Even back in 1785, Withering understood the limits of digitalis – especially when given in large and oft-repeated doses. For instance, he wrote:
The Foxglove when given in very large and quickly repeated doses, occasions sickness, vomiting, purging, giddiness, confused vision, objects appearing green or yellow; increased secretion of urine, with frequent motions to part with it, and sometimes in ability to retain it; slow pulse, even as slow as 35 in a minute, cold sweats, convulsions, syncope, death.
When given in a less violent manner, it produces most of these effects in a lower degree; and it is curious to observe, that the sickness, with a certain dose of the medicine, does not take place for many hours after its exhibition has been discontinued.
Let the medicine therefore be given in the doses, and at the intervals mentioned above…
Though much of what Withering discovered in in 1785 was still in its initial phases (as he himself admitted), on this point he was certainly on the right track. Today clinicians identify potentially life-threatening digoxin toxicity from specific clinical signs, including:
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