A collaboration between the French National Centre for Scientific Research (CNRS), University of Toulouse and fine chemicals firm Isochem, has resulted in the development of a novel synthetic process for biodegradable polymers that could be used in drug delivery in place of conventional tablets, capsules or syrups.
The advantage of these biodegradable polymers for use in drug delivery is that they can be readily broken down by water in the body, thus releasing the drug treatment into the body. Depending on the particular biodegradable excipient, this can occur over a period of a week, a month or as much as six months, removing the necessity of repeated injections or tablets.
Some biodegradable polymers (such as polyesters) are already used as pharmacological excipients, but their use is restricted due to the limited number of active substances they can be combined with. The research team sought to expand the range of potential active substances that can be delivered by controlled-release systems by increasing the diversity and accessibility of polymers.
The team succeeded in producing a wide variety of polymers that could be applied for use in controlled release drug delivery by developing a synthetic process involving O-carboxy anhydrides, which are much more reactive than the monomers traditionally used (lactide and glycolide).
Traditional methods of polymer preparation also involve several hours' reaction time at high temperatures (140°C-160°C), whereas this new method requires only a few minutes at 25°C.
A wider choice of available biodegradable polymers increases the chances that an appropriate biodegradable excipient can be found for a given active substance, including much more complex drug formulations which would not have been possible previously.
In addition to this, by avoiding the oral route and administering the treatment as an injection, less of the drug would be required as there would be no need to account for its partial destruction as it passes through the digestive tract.
Dr Didier Bourissou, who led the group over three years of research, believes the study could have real implications for the future of drug delivery:
"Such things were not available [previously] because the structural diversity was not there," Dr Bourissou told In-PharmaTechnologist.com.
"Polymeric excipients should now be able to play a more sophisticated role than they used to, we can take all the advantages of excipients and improve them."
He hopes that these polymers, or 'smart excipients', may themselves eventually carry out some form of biological activity.
Two patents have jointly been taken out by all three parties, covering the methodology involved in the new synthetic process as well as the structural diversity of the resulting polymers.
"The next step is to apply the method to a few cases to assess limitations and potential - we need to apply it to a given formulation problem," said Bourissou. The active substances that are likely to be involved in the next stage of research are anti-cancer drugs and human growth hormone, both of which can be used with existing biodegradable polymers.
The group are currently in discussions with an undisclosed chemical company regarding applying the process on a 1Kg scale, but remained tight-lipped on any further details.