Unfortunately, there is very little clinical research exploring the specific interactions between CBD and pharmaceutical drugs. That being said, it is thought that CBD is quite safe to use in conjunction with most medicines and does in fact have synergistic benefits with some. There are some pharmaceuticals that will interact with CBD, as they are often processed by the same enzymes, such as CYP450.
NSAIDs
Using CBD alongside NSAID's is generally safe. In fact, studies show that co-administration can actually boost the analgesic effects of traditional pain medications like NSAID's.
NSAIDs and CBD are both processed primarily by the liver. If your dog suffers from chronic liver disease, it is a good idea to administer the two at different times; at least 2 hours apart is best.
You may find by adding the CBD into their regimen, you can ease off on the NSAIDs for pain and inflammation.
STEROIDS
It is best to avoid taking steroids alongside cannabis medicine or at least stagger their use by 2-3 hours.
According to our veterinary advisors, CBD can prolong the half life of steroids, increasing their blood concentration over time. This may have deleterious side effects.
VETORYL
There is limited clinical research regarding the use of Vetoryl and CBD.
Our veterinary advisors agree that there is minimal risk of co-administering Vetoryl or trilostane alongside CBD. We have numerous clients who are successfully using the two together. Make sure your vet is aware of your CBD use so they can monitor your dog for any changes. It is also a good idea to leave a window of between 2-3 hours between administering the two if you can.
If you are concerned about the potential interactions of a drug with CBD, it's best to speak with a medical professional who understands how those drugs work. Unfortunately, many vets are not familiar with cannabis and CBD, so they may not be able to advise on the administration of these therapies.