Our laboratory doesn’t just study medicines in Australian marsupials, we also undertake studies to look at medicines in many species including cats, dogs and sheep.
The other major study we are undertaking currently in our pharmacology laboratory is to see if the medication mefloquine may potentially be a treatment for feline infectious peritonitis (FIP). FIP is a viral infection that can affect younger cats. FIP as a disease is not that common, but veterinarians looking after pet cats would unfortunately, see several cases a year. A diagnosis of FIP is not good news for the patient and devastating for the owners. It is difficult to prevent this disease and the current approach to treatment of FIP relies on the use of immunosuppressive agents to dampen clinical signs temporarily. Yet, there are no viable treatments that address the underlying problem of viral replication.
Our veterinary pharmacology laboratory has teamed with colleague Associate Professor Jacqui Norris as she and her previous research student Dr Phillip McDonagh found that mefloquine will inhibit the FIP virus in the ‘test-tube’.
Mefloquine is a medicine that has been administered to people to prevent malaria. It has been in the news over the past year as it was given to the Australian Defence Forces personnel to prevent malaria and has reportedly resulted on some adverse side effects.
So before mefloquine is given to sick cats with FIP, the aim of our project is to obtain as much information as possible on how the feline body is likely to deal with ‘mefloquine’. Although we won’t get all the answers we need to tell us how cats deal with mefloquine dosing; we can get some information to help us predict what is likely to happen. We know mefloquine is ‘metabolized’ by the liver in people. So we can compare the rate that mefloquine is metabolized in people (because this information is reported in the scientific literature) with the rate that mefloquine is metabolized by feline enzymes that occur in the liver. (Feline metabolism enzymes can be purchased and that is how we have acquired them).
The cat is known to have trouble metabolizing some medicines, so this project is to investigate if the cat will take longer to metabolize the mefloquine than people or dogs. If the cat is taking longer to metabolize the mefloquine than other species, then we need to know this and reduce the dosage accordingly if clinical trials go ahead.
This project commenced during 2016. The project is being undertaken by PhD candidate Aaron Izes. He is doing a fantastic job. He has completed developing the assay for measuring the mefloquine concentration in feline blood. Metabolism that takes place in the liver has two phases. The two phases are defined by different chemical breakdown pathways. Aaron is in the process of completing looking at the difference in the rate of Phase I metabolism in cat verses dog microsomes. After the phase I study we will be looking at whether there are differences in phase II metabolism between these species. Our laboratory has not done studies in Phase II metabolism before, nor does it seem have many other veterinary researchers. So we are looking forward to developing the Phase II assay.
This is an exciting study for our laboratory and potentially will be very helpful to develop methods to look at medicine metabolism in many animal species without the need to administer the medicine to the live animal.
We are very grateful for the financial support of this project by the Winn Feline Foundation, Australian Companion Animal Health Foundation and the Feline Health Research Fund.