Does Pain Medication Affect Men and Women Differently?

I've read that pain medication affects men and women differently, is this true?

There is no gender difference in how pain medications affect men and women. However, you bring up an interesting topic which will be a major issue in the future, which is the difference in how different people metabolize drugs and how this difference determines their responsiveness to drugs.

Many drugs are metabolized in the liver by a process called the cytochrome P450 system. This system has many different subtypes, with different drugs being metabolized by specific subtypes. One issue is the interactions which can occur when two drugs using the same metabolic system subtype are given to a patient. A second issue involves the variations which exist within any subtype. One person might breakdown a pain medication into inactive by products very quickly. Such a person would have little of the active drug present and would get no effect from the medication. Another person might be unable, because of the genetic variation, to metabolize the drug at all and would be at risk for overdosing. One of the exciting new frontiers of medicine will be the ability to determine, which genetic variant of a cytochrome P450 subtype any given person has and then, from that, determine how they would respond to a specific drug or combination of drugs.