Impotence drugs help treat brain tumours

Impotence drugs help treat brain tumours
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28/07/2008

Impotence drugs may help carry cancer-fighting drugs through the brain to
treat malignant tumours, U.S. researchers reported on Monday.

Tests in rats showed two erectile dysfunction drugs -- Schering-Plough's
Levitra and Pfizer's Viagra -- helped carry a chemotherapy drug past the
blood-brain barrier, the team at Cedars-Sinai Medical Centre in Los
Angeles said.

Rats with brain tumours lived 42 days when injected with the cancer drug
adriamycin. But when they also got Levitra, known generically as
vardenafil, the rats survived an average of 53 days. Levitra appeared to
be more effective, the researchers reported in the journal Brain Research.

Levitra and Viagra, known generically as sildenafil, are in a class of
drugs known as PDE5 inhibitors. They were originally tested as heart drugs
because they increase blood flow in small vessels.

"We chose adriamycin for this study because it is one of the most
effective drugs against brain tumour cell lines in the laboratory but it
has very little effect in animals and humans because it is unable to cross
the blood-brain tumour barrier," neurosurgeon Dr. Keith Black, who led the
study, said in a statement.

"The combination of vardenafil and adriamycin resulted in longer survival
and smaller tumour size," Black said.

The blood-brain barrier is a molecular mechanism that keeps harmful agents
out of the brain. Brain tumours grow little blood vessels to supply
themselves with nutrients and these also have a barrier, called the
blood-brain tumour barrier.

Black said the impotence drugs appear to affect the tumour blood-brain
barrier but not the larger blood-brain barrier, which may help doctors use
chemotherapy drugs to kill off brain tumours without damaging healthy
brain tissue, he said.