Phenobarbital and CBD are known to both use the Cytochrome P450 system for hepatic metabolism therefore it stands to reason that co-administration could result in altered metabolism of one or both of these drugs.

In a recent study by Doran et al (https://doi.org/10.2460/ajvr.21.08.0120), changes in CBD pharmacokinetics (PK) were discussed, in reference to phenobarbital. Interestingly, no apparent changes in PK of phenobarbital or CBD were noted when each drug was given ONCE (not chronic dosing).

Significant changes in serum ALP were noted during chronic (3 week) CBD dosing at 10 and 20 mg/kg/d. More dogs had a chance in serum ALP concentration at the higher dose, but the sample sizes were very small so it is difficult to extract too much information from that finding.

Also interesting, the maximal concentration of CBD was higher in fed animals, than in those fasted at the time of CBD administration. Food for thought...

What is the take away?
1. CBD alone can cause elevated ALP in dogs. Significance? Not addressed in this study.
2. We don't know how phenobarbital serum concentrations are affected by chronic or single dose exposure to CBD, because this wasn't studied as a separate question.
3. This study didn't tell us anything about dose escalations so if you are using CBD oil in your practice, please look elsewhere for dosing recommendations for efficacy!

**Disclaimer: the State of Wisconsin forbids prescribing or recommending CBD containing products by veterinarians. Please consider this TidBit informative and not a recommendation for treatment with CBD containing products for pets.**

Short and sweet this week! Have a great week and I hope to work with you soon!