I was just looking it up and found an article about Diltiazem precautions: http://heart-disease.emedtv.com/diltiazem/diltiazem-precautions-and-warnings.html
I was searching for this because I haven't been told about any possible side effects by my CRS nor is there any literature with the ointment so I felt pretty much "in the dark" about the does and donts associated with it. After reading i'm glad I haven't got hypotension instead of hypertension or I wouldn't be able to use the ointment!