Question: A patient (5-foot-2, 120 pounds) is prescribed an acetaminophen-codeine product to treat pain following a surgery. Two days later, they return, requesting a "stronger" painkiller, claiming that taking two or even three tablets did not have any effect. You don't know this person very well and you wonder why the medication might not have worked. Consider the liver's metabolism of codeine; could there be a pharmacokinetic reason why two or three acetaminophen-codeine tablets did not have any effect on this patient's pain?