Case 1.
YT and DM both underwent elective orthopedic procedures and are experiencing acute pain. Using a standardized postoperative management plan on Day
#1, both patients received low doses of IV hydromorphone (0.5mg, q4h, PRN) and PO acetaminophen with adequate pain relieve. On Day
#2 IV hydromorphone was discontinued and a new regimen of acetaminophen 1000mg q8h, tramadol 75mg q6h and codeine 60mg q4h was started. DM had adequate pain control but after a few doses developed nausea and vomiting; YT had very poor pain relief, limiting their participation in physical therapy. Based on the information provided, what is the best explanation this drug regimen should be changed?

a. YT is an ultra-rapid metabolizer of CYP2D6, while DM is a poor metabolizer of this sub-family.
b. YT is a poor metabolizer of CYP2D6 while DM is an ultra-rapid metabolizer of this sub-family.
c. YT is a poor metabolizer of C219 and codeine and tramadol are both pro-drugs.
d. YT and DM response to the drugs are not influenced by genotype, but reflect their individual pain experiences.