In 2009, The New England Journal of Medicine reported the case of an otherwise healthy 2-year-old boy in Canada who died after surgery. He had received a codeine dose in the recommended range, but an autopsy revealed that morphine (a product of codeine metabolism) had built up to toxic levels in his blood and likely depressed his breathing. Genetic profiling revealed him to be an “ultrarapid codeine metabolizer,” due to a genetic variation in an enzyme known as CYP2D6, part of the cytochrome P-450 family.
While codeine is no longer used at Boston Children’s Hospital, it’s this kind of genetic profiling that Shannon Manzi, PharmD, would someday like to offer to all patients—before a drug is prescribed.
Not all people respond the same way to drugs. The results of randomized clinical trials—considered the gold standard for drug testing—often produce a dose range that worked for the majority of the patients in the study. They don’t take people’s individuality into account, and that individuality can dramatically affect drug efficacy and toxicity.
Adverse reactions are more common than you might think. …