Expert: Ronald Levy, M.D. - 7/29/2011

Question
I am scheduled for my first colonoscopy next month. I understand I will be getting IV sedation and pain meds during the procedure. I am worried I might not receive the full benefit of these drugs because I am an intermediate metabolizer for CYP4502D6. I am not scheduled to meet with the doctor in advance of the procedure so cannot convey this info until the day of the test. Even though I am 53 yrs old, I have never had surgery, anesthesia, IV sedation or narcotic pain relievers so I cannot answer any questions about what has worked or not worked in the past. I simply don't know.

To further explain, I have had many years of BAD experience with psych drugs metabolized at CYP4502D6. I am bipolar and OCD. I either usually don't respond to the medications at all, or become sick with side effects even at the smallest dose. Because of this, I take no drugs at all for bipolar, and 60 mg per day of buspar for OCD. I may not have a good understanding of this, but I think the buspar I am currently taking further suppresses 2D6.

My questions are:
Should I be concerned which drugs are given during the colonoscopy procedure? Should I try to meet the doctor ahead of time and explain all this? Will I receive sufficient sedation and pain control during the procedure? Am I making a mountain out of a molehill?

Thank you for your advice and information. I don't want to obsess about this for the next month.

Answer
Generally, this disorder is related to a large class of medications that activate the Cytochrome P450 system. To my knowledge, three of the drugs they would likely use on you (Midazolam, Fentanyl and Propofol) are not metabolized by that pathway, so you should be able to have your procedure without much problem. I would probably recommend having the procedure with an anesthesiologist doing the sedation and not the GI doctor and his nurse (as is common practice most places). I would certainly mention this to your physician and anesthesiologist prior to the procedure.

Hope this helps,

Ronald Levy, MD
Professor of Anesthesiology
UTMB-Galveston