It would appear your product might not be a medical device as you have indicated it has a pharmacological, immunological or metabolic action in the body.
Your product may however, be another sort of therapeutic good regulated in another way. You can find more information at Basics of therapeutic goods regulation.
You can also use the ‘Is my product a therapeutic good?’ decision tool to assist you to determine if your product is another kind of therapeutic good.
If your product is already included in the ARTG as medical device, you should consider cancelling your entry from the ARTG. If you choose not to cancel your product at this time, the TGA may investigate the regulatory status of your product in the future and elect to take action to cancel it from the ARTG.