A drug used to treat erectile dysfunction is emerging as an unlikely medication for people at risk of heart failure.
In a paper soon to be published in the journal Scientific Reports – and available on the pre-print site bioRxiv – researchers led by Andrew Trafford from the UK’s University of Manchester describe the life-saving effect of Tadalafil, which is similar to Viagra, on sheep at risk of heart failure.
Heart failure (HF) is a serious condition with a high fatality rate. It arises when the heart’s muscles are no longer strong enough to pump blood through the body. Onset can be sudden or chronic, and contributing causes include coronary artery disease and high blood pressure.
The condition, wrote a team of researchers headed by Wolfram Doeher from the Berlin Centre for Stroke Research, Germany, in 2017, “is a complex clinical syndrome with multiple interactions between the failing myocardium and cerebral (dys‐)functions”.
“Moreover,” they continued, “neuro‐cardiac feedback signals significantly promote aggravation and further progression of HF and are causal in the poor prognosis of HF.”
Not surprisingly, available treatment options for people with heart failure are few.
Now, however, Trafford and colleagues have demonstrated that Tadalafil – a drug already widely used, albeit overwhelmingly by men – may represent a new and efficient treatment option.
The drug targets an enzyme called Phosphodiesterase 5 (PDE5S), which regulates how tissue responds to hormones such as adrenaline. Heart failure is characterised by a signalling cascade – a series of increasingly damaging chemical reactions, each catalysed by the one that precedes it. It starts with the inability to respond to adrenaline.
Trafford’s team found that blocking PDE5S changed the cascade by restoring the heart’s ability to interact with adrenaline. It also – in an outcome not wholly dissimilar to that achieved through its main advertised use – tightens the heart muscles up a bit and makes them pump more effectively.
The researchers made the discovery by using sheep fitted with pacemakers. The little machines were used to induce heart failure, after which the ailing animals were pumped full of the drug. In a very short period of time the progressive effects of HF abated, and even the early symptoms went into reverse.
Trafford says he is pleased with the results but cautioned against people deliberately taking Tadalafil as an HF prophylactic – at least until a lot more research has been done.
“This is a widely used and very safe drug with minimal side effects,” he says.
“However, we would not advise the public to treat themselves with the drug and should always speaking to their doctor if they have any concerns or questions.”
The heart-restoring effects of the drug are not wholly surprising to scientists in the field.
Commenting on the study, Metin Avkiran of the British Heart Foundation says it’s a case of history repeating itself.
“Viagra-type drugs were initially developed as potential treatments for heart disease before they were found to have unexpected benefits in the treatment of erectile dysfunction,” he notes.
“We seem to have gone full-circle, with findings from recent studies suggesting that they may be effective in the treatment of some forms of heart disease – in this case, heart failure.”
Andrew Masterson is a former editor of Cosmos.
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