Q. I have been unable to tolerate most medicines without experiencing bad drug side effects. My doctor does not believe me. She prescribes medications with names I don’t recognize and I react badly to them. My mother and daughter have the same problem.
Just to illustrate, children’s cough medicine with codeine put me in the emergency room with a drug overdose. Antihypertensive drugs dropped my blood pressure to 40/30. Prilosec gave me horrible abdominal pain. It seems the list is endless. Is this an actual condition?
A. We are shocked that your physician does not seem to be aware of the reason for your super-sensitivity to codeine. There is a very good likelihood that you metabolize drugs differently than many other people, which would account for the overdose you experienced.
Codeine is converted to morphine in the body, but this requires an enzyme called CYP2D6. Some people are ultra-rapid metabolizers, which means they quickly transform codeine into morphine, which in turn can lead to overdose. This is especially dangerous in vulnerable children and has led to accidental deaths.
The fact that your mother and your daughter are also highly susceptible to drug side effects suggests that you all have a similar genetic profile. Prescribers should take this into account and modify doses accordingly.
Slow Metabolizers May Also Be Super-Sensitive to Drug Side Effects:
Some people have a genetic makeup that makes it hard for them to metabolize many medications. Take caffeine, for example. There is an enzyme in the liver called CYP1A2 that is largely responsible for deactivating caffeine. A “normal” person will quickly absorb caffeine from coffee or tea and begin to experience the stimulant effect within about half an hour or less. It would normally persist for a couple of hours, gradually tapering off.
People who have a modified CYP1A2 gene may experience a greater buzz from caffeine that persists longer because their bodies do not have the ability to metabolize the drug quickly. A slow caffeine metabolizer should limit caffeine consumption.
There are dozens of other enzymes that are responsible for ridding the body of thousands of drugs. Many people have genetic variants of the genes that make those enzymes and hence are far more susceptible to drug side effects than others. If you suspect that you are someone who is super-sensitive to medications, you can ask your physician to run a genetic profile on your enzyme activity. That way she may be better able to tailor a dose to suit your physiology.
