Amantadine and kidney issues

Hi, I have a 17-year-old cat who has arthritis. He is taking Metacam, gabapentin and amantadine for pain relief. The amantadine was just added a few weeks ago. He has never had any kidney issues previously, but his blood test this week shows elevated markers. I know Metacam has been linked with kidney issues, but I was wondering if there was any chance the amantadine could cause this? The elevated markers have only started since he took the amantadine. Any information would be much appreciated. Thanks!

Hello and thank you for this interesting question- Im sorry for the delay in answering it. Amantadine is a pain killer specifically for neuropathic pain, which is pain originating from the nervous system and not from the muscles ("neuromuscular pain" eg in arthritis, treated by NSAIDs).  It is frequently used alongside Metacam.  Side effects are usually gasterointestinal in nature eg vomiting, diarrhoea etc and I know of no concerns around the kidneys.  Your vet could double check this for you. However, there are known concerns regarding damaged kidneys and long term Meloxicam use; vets often perform regular kidney tests when pets are on Meloxicam for this reason.  It may therefore be a case that corrolation (the pattern being spotted at the same time) is not the same as causation ( what caused the problem). Has your vet conducted a drug review?