Designing liposomes to avoid chemotherapy side effects
17 February 2006
Katharine Sanderson/St Louis, US
The side effects of a common chemotherapy agent, cisplatin, can be avoided if the molecule is encapsulated in a finely tuned liposome, claim Danish biophysicists.
Ole Mouritsen at the University of Southern Denmark and colleagues have encapsulated cisplatin molecules in liposomes. The encapsulated drug can be delivered straight to the centre of a tumour, said Mouritsen.
The lipid-bilayer that surrounds the liposomes breaks open in the unique environment of the tumour, he said. The drug is then released at a rate sufficient to kill the tumour but too low to poison surrounding tissue. This controlled drug release eliminates side effects, such as kidney damage, nerve damage, nausea, hearing loss and hair loss.
Liposomes have been investigated as drug-delivery capsules before, but are not in common use because of problems releasing the drug from the shell. Mouritsen says that getting the drug out of the capsule is not a problem if the liposome is properly designed.
Understanding the physical chemistry of liposomes is essential, he said. 'If you can control making the capsule, the basic physical chemistry gives you the tools,' Mouritsen told the American Association for the Advancement of Science.
Mouritsen studied changes in the lipid bilayers under different temperatures and in different environments. This provided the information needed to design a liposome that will only open up and release the drug once it hits the tumour.
The drug-laden liposomes are injected intravenously. They penetrate the spongy blood-vessel system developed by tumours, and accumulate in the tumour before they break open.
The capsules are being developed with Danish biotech firm LiPlasome. They are undergoing toxicology trials now and are expected to enter clinical trial by the end of the year.