Polymer promise for drug delivery

Scientists at Rutgers University have developed a ‘smart’ polymer drug carrier that seeks out diseased cells and a gel ‘medicine cabinet’ injected under the skin to supply drugs to the body.

Scientists from Rutgers, the University of Medicine and Dentistry of New Jersey (UMDNJ) and the Cancer Institute of New Jersey (CINJ) University have developed a ‘smart’ polymer drug carrier that seeks out diseased cells and a gel ‘medicine cabinet’ injected under the skin to supply drugs on an as and when required basis.

The ‘smart’ polymer, taken orally as a pill or injected, can be targeted to release its drugs in specific organs or cells by means of ligands, a variety of compounds that interact only with the receptors on certain types of cells.

‘We attach the drug or drugs to the polymer and then we attach the ligand,’ said Patrick J. Sinko, chairman of the department of pharmaceutics in Rutgers’ College of Pharmacy. ‘The ligand is like the address on a package, making sure the polymer with its drug or package of drugs goes directly to the diseased cell.’ When it reaches its destination, the ligand hooks up to the cell surface and permits the polymer and its drug payload to pass into the cell, the researcher said.

Sinko and his colleagues, Michael Leibowitz and Stanley Stein of UMDNJ-Robert Wood Johnson Medical School, have also shown that without the targeting ligands, the drug-polymers are unable to penetrate cells.

When injected under the skin, the polymer gel drug carrier forms a tiny lump or ‘button’ that serves as a minuscule medicine cabinet, delivering multiple drugs to patients in a controlled fashion over days, weeks or years, said Sinko.

‘The gel is ideal for certain types of patients, such as elderly patients or schizophrenic patients who tend to forget to take their medicines, or for certain kinds of injected drugs where a controlled release significantly improves therapeutic outcomes,’ said Sinko.

When the button is gone, the patient or caregiver knows that it is time to get another injection, Sinko added.

Animal tests have reportedly proven so promising that a company, Theraport Biosciences, has been formed to further develop the technology in co-operation with, and under license to, the universities.

Using polymers to transport drugs has overcome another basic problem of pharmacology in that most drugs are fatty compounds that don’t dissolve in water and are difficult for body tissues to absorb.

Putting them inside a polymer matrix is said to make them water soluble and gives them better pharmaceutical properties, the researchers found.

Sinko noted, until now, camptothecin, a powerful drug designed to fight cancer, has not been marketable because it is virtually insoluble and difficult for the body to absorb. ‘But attaching it to a smart polymer drug carrier not only made it soluble and useable, it made the drug 30 to 50 times more potent’ added Sinko.