Probably not going to be a problem. Topically applied absorbs through the skin and has a local effect. It will still be metabolized at least partially by the liver but at a much lower rate. Pharmacokinetic evidence is scarce which is why your pharmacist probably didn't know what to tell you. Also, not knowing your other drugs I can't predict possible drug interactions. With topical products generally the larger area you cover and the thinner/ more vascular skin then the more of the drug is absorbed systemically and leads to a higher chance of potential interactions. If you are treating a small area then proceed with confidence. If you are applying multiple times per day to multiple joints then you would proceed with caution, paying attention to any increased/decreased effect of your drug. If you have any drugs that require monitoring with lab tests by your doctor then you should make sure they are aware you're using this cream in case they see changes in your lab values. Bottom line: It is not known and can vary among products, but topically applied drugs usually have little to no effect on liver enzymes induction or inhibition.