Heart drug may help treat stroke

[Guest guest]

Heart drug may help treat stroke

US researchers have discovered a group of plant extracts that may have

benefits in early treatment of stroke.

Cardiac glycosides, compounds which include heart drug digoxin, were found to

protect rat brain tissue against the lack of blood which occurs in stroke.

The study published in the National Academy of Sciences may help scientists

develop new treatments.

Many drugs thought to have protective effects after stroke have been tested

but as yet none have been effective.

 

The researchers from Duke University Medical Center in North Carolina

screened a large number of small compounds for neuroprotective activity by

testing

them on slices of rat brain deprived of oxygen and glucose.

 

" It was surprising because this is a class that is generally toxic "

Dr Donald Lo, lead researcher

 

Using the test - which is designed to mimic stroke in the brain - a compound

called neriifolin which comes from the yellow oleander was found to be

significantly protective against neurons in the brain that otherwise would have

died.

Neriifolin appeared to show neuroprotective properties even if given several

hours after the brain tissue was starved of oxygen and glucose.

Although they hadn't initially been identified in the screening test, the

researchers hypothesised that several other compounds related to neriifolin

would also protect brain tissue against ischaemic injury.

They tested digoxin and digitoxin - which come from the foxglove and have

both been used for several decades in the treatment of congestive heart failure

and arrhythmia - and ouabain in a mouse model.

Although not as potent as neriifolin, all of the plant extracts had a

neuroprotective effect.

Clinical trials

The researchers said as cardiac glycosides are already in use, it could speed

up the process towards clinical trials.

Dr Donald Lo, Director of the Center for Drug Discovery, at Duke University,

said: " It's always a helpful stroke of luck when you find something that

already has clinical usage because we know many things about dosage and

side-effects. "

He added that finding the activity of the compounds in the rat model was the

very first step.

" The aim of this study was to survey as many different drug targets as

possible because the last 50 to 100 that have been tested have not fared well in

clinical trials. "

He added: " It was surprising because this is a class that is generally

toxic. "

A spokesperson for the Stroke Association said: " The researchers are correct

in identifying the failure of many compounds that have shown the potential to

protect neurons between the stage of animal model testing and clinical

trials, and it is welcome to have other compounds to investigate.

" The advantage of this group of compounds is that they have been in clinical

use for other conditions over many years, and we therefore know a great deal

about the possible doses and side effects.

" The negative side is that these drugs have effects on the heart that will

certainly limit the doses that could be given, and it has been the case with

other neuroprotectant drugs in the past that cardiac side effects have meant

that insufficient amounts of drug to protect the brain cold be given safely.

" [This model] might be useful as a means of identifying candidate drugs in

the future.

" However, the difficulty usually arises not in identification of possible

neuroprotectant molecules but in their successful translation into clinical

trials, and our track record speaks for itself.

" Over the past 15 years there have been dozens of molecules that have gone as

far as clinical trials involving tens of thousands of patients after showing

great promise in animal studies, yet we still have no drug of this class

that is effective. "

Story from BBC NEWS:

http://news.bbc.co.uk/go/pr/fr/-/1/hi/health/5095596.stm

 

Published: 2006/06/24 22:55:40 GMT

 

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