A venomous lizard usually found in the wilds of Mexico and Arizona has given researchers fresh inspiration for a treatment that can counterbalance one of the main side effects of antipsychotics. The saliva of the Gila (pronounced hee-la) Monster contains a protein that has been found to reduce blood glucose levels. Second generation antipsychotics such as olanzapine and clozapine often cause the unwanted side effects of hyperglycaemia (high blood sugar) and Type II diabetes, however it has been found that the lizard’s protein can help to control these issues.
Remarkably, this protein is very similar to a hormone already found in the human body that helps to regulate levels of insulin and glucagon (a hormone that increases the level of blood glucose). A synthetic replication of the Gila Monster’s protein, called liraglutide, has since been created and approved for therapeutic use as an anti-diabetic drug in the US, Europe and now Australia.
The efficacy of liraglutide in stabilising glucose levels and promoting weight loss caused our researchers, led by Dr Katrina Green, to investigate whether the drug could be used as a co-treatment with current antipsychotics such as olanzapine and clozapine. Results of an initial study, which was supported by funds raised via the SunCorp Brighter Futures program, have revealed that using liraglutide as a co-treatment alleviated olanzapine-induced glucose dysfunction, but not the hyperglycaemia caused by clozapine.
“This tells us that liraglutide is effective at clearing glucose from the blood,” explains Dr Green, “which may prevent diabetes, a common side effect associated with olanzapine, in the long term. We still need further studies to investigate other potential metabolic benefits of liraglutide co-treatment, such as weight loss and cardiovascular protection, however the results are looking very promising so far.”
Diabetes has also been shown to exacerbate cognitive deficits in people with schizophrenia, so there is hope that using liraglutide as an adjunct treatment can also improve impairments in attention and memory. “This is something we really want to focus our future studies on,” says Dr Green. “We’re keen to start looking into the potential long term cognitive effects that liraglutide may bring.”