Impotence drugs may help carry cancer-fighting drugs through the brain to treat malignant tumours, US researchers reported.
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.
Test results very positive
"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. – (Reuters Health)
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