QuestionSBA
QuestionChoice
This should never be the first diagnosis for a patient complaining of inadequate analgesia. A range of analgesia should be trialled, and a thorough drug and social history relating to opiate drug use and previous presentations to medical services should be taken prior to considering drug-seeking as a diagnosis. Also, this patient has already been diagnosed with appendicitis - so will be in considerable pain, making it completely reasonable for him to require additional analgesia.
10000690
e
Drug-seeking behaviour
QuestionChoice
Codeine is metabolised by the enzyme CYP2D6, not by CYP450. Also, this patient's lack of response to codeine would be caused by CYP2D6 polymorphism with poor metaboliser effect, not ultra-rapid metaboliser effect.
10000688
c
CYP450 polymorphism with ultra-rapid metaboliser effect
QuestionChoice
Codeine is metabolised by the enzyme CYP2D6, not by CYP450.
10000689
d
CYP450 polymorphism with poor metaboliser effect
QuestionChoice
Codeine is metabolised by the enzyme CYP2D6 in the liver, which converts codeine into morphine - its active metabolite. CYP2D6 polymorphism with ultra-rapid metaboliser effect, meaning two copies of the CYP2D6 gene with increased activity, would cause Codeine to be rapidly broken down into Morphine, leading to an exaggerated response to Codeine and possible opiate toxicity. This is the opposite to this patient's findings, meaning that he has CYP2D6 polymorphism with poor metaboliser effect, rather than an ultra-rapid effect.
10000687
b
CYP2D6 polymorphism with ultra-rapid metaboliser effect
QuestionChoice
Codeine is metabolised by the enzyme CYP2D6 in the liver, which converts codeine into morphine - its active metabolite. This patient likely has CYP2D6 polymorphism with poor metaboliser effect, meaning that he has two inactive copies of CYP2D6. This means that pain relief is inadequate with codeine as it is unable to be converted into morphine.
10000686
a
CYP2D6 polymorphism with poor metaboliser effect
Concept
Chapter
2693
3808
Cytochrome P450 enzymes
Topic
166
General pharmacological concepts
12684
A 32-year-old male presents with appendicitis. Whilst waiting for surgery, he is given 60mg of codeine for pain relief. One hour later, he is still complaining of the same level of pain, and says that the codeine has not helped at all.

Which of the following is the most likely explanation for this?
a