Microwaves enable co-crystallisation to improve properties of drugs

Microwave radiation could provide a faster more and environmentally-friendly way to manufacture drugs, according to researchers at Bradford University.

Published in the Royal Society of Chemistry journal, CrystEngComm, the research is the first to show that microwave radiation can be effectively used for co-crystallisation, a process which creates single crystals constructed from two compounds.

According to the university, drugs manufactured from these co-crystals can have improved properties such as longer shelf-life, improved solubility and easier absorption into a patient’s bloodstream.

Using caffeine and maleic acid as example compounds, the researchers achieved 100 per cent crystallisation in one minute using very little solvent.

Prof Paradkar, director of Bradford University’s Centre for Pharmaceutical Engineering, said, ‘We chose caffeine and maleic acid as these compounds have different levels of solubility which is a common problem in pharmaceutical manufacturing.

‘Conventional methods of co-crystallisation aren’t effective when you’re working with two compounds that dissolve differently, but we found that by using microwave radiation we could still get excellent results.’

The team worked with five different solvents, of which water and methanol produced the best results. These two solvents were able to transmit the heat from microwave radiation more effectively than the others tested: acetone, ethyl acetate and toluene.

The experiments have only, to date, been carried out at laboratory scale, but Prof Paradkar believes that, if the process can be scaled up, it could offer significant benefits to the pharmaceutical industry:

‘Other methods of co-crystallisation, such as solvent crystallisation, grinding or ultrasound, all have associated problems, for example increased use of solvents or lack of purity in the resulting co-crystals,’ he said in a statement. ‘Our research shows that microwave radiation is a very promising alternative for producing pure co-crystals quickly, with limited use of solvents.’