The idea of using beeswax mixed with the more traditional polyethylene-oxide (PEO) coating for medications came from Dr Michael Mucalo, a senior lecturer in chemistry at the University. He wanted to find a better way to deliver drugs used, among other things, for treating mastitis in dairy cows.
"Dosing livestock is stressful for the animal, and expensive and time-consuming for the farmer, so I was looking for a medium that would provide steady delivery of a drug over days or months," he says.
"I'd been trying to find ways of slowing release from PEO and I'd trialled many types of additives with no success. And then I recalled seeing beeswax on the shelf of a lab in a local company where I'd spent a sabbatical, and thought I’d give it a go."
The next step was to get into the lab and do some experiments. Dr Mucalo's Summer Research Scholarship student Ho Ying Yuen was tasked with creating some samples of different beeswax-PEO mixes containing an aspirin-like drug. She then tested them to see how long it took for the drug to be released into a medium that mimicked biological membranes.
"At first we had problems making the sample disks," says Ms Yuen, who is partway through a Bachelor of Science (Technology) degree. "We tried using lids as moulds, but we couldn't release the samples. Michael came up with the idea of using a silicone muffin tray, and then it was easy."
The test results showed beeswax slowed down the drug release considerably compared to PEO alone. "It took almost a week for the entire drug to be released from the disks made with beeswax," says Ms Yuen. "By comparison, we found 60-80% of the drug in the PEO disks was released in the first four hours, and within 48 hours it had all been released."
Dr Mucalo says these findings are a useful first step towards developing more user-friendly veterinary medicines. "Adding more PEO to the beeswax mix increased the rate of drug release, which means it would be easy to tailor the release rate for different drugs."