Outline the genetic variations in the cytochrome P450 2D6 enzyme and discuss the clinical relevance for drugs used in the perioperative period.
This enzyme is responsible for much of the variation in efficacy and toxicity of some commonly used drugs.
This enzyme metabolises tramadol into a more active metabolite TRUE/FALSE
Ondansetron may be ineffective with poor metabolisers TRUE/FALSE
Patients from the middle east are more likely to be ultrarapid metabolisers TRUE/FALSE
Approximately 90% of caucasians are poor metabolisers TRUE/FALSE
This enzyme metabolises codeine into a more active metabolite TRUE/FALSE
Sticking with neuraxial opioids…
Intrathecal fentanyl has fewer adverse effects than intrathecal morphine TRUE/FALSE
Intrathecal morphine produces better postoperative analgesia than intrathecal fentanyl after LSCS TRUE/FALSE
Doses of intrathecal morphine greater than 50mcg have no greater benefits in terms of analgesia but carry a higher incidence of respiratory depression TRUE/FALSE
100 mcg of morphine is 0.1ml of morphine 10mg/ml TRUE/FALSE
extended-release epidural morphine is associated with less respiratory depression than IVPCA morphine TRUE/FALSE
This has been a popular topic in vivas (and the occasional SAQ) for ages. It’s an important and relevant topic that is not always well-covered in the basic texts.
BT_PM 1.18 Describe the pharmacology of opioids deposited in the epidural space or cerebrospinal fluid
With regard to epidural fentanyl (1 mcg.kg-1)
plasma concentrations of fentanyl are similar to the same dose given intramuscularly TRUE/FALSE
the duration of analgesia is 1 hour TRUE/FALSE
the CSF concentrations of fentanyl are maximal at 50 minutes TRUE/FALSE
the incidence of pruritis is greater than following an equi-analgesic dose of epidural morphine TRUE/FALSE
the onset of analgesia is around 2-5 minutes because fentanyl is highly lipid soluble TRUE/FALSE
It’s such fun being able to use so many different routes to administer drugs in our jobs. So many doctors out there don’t get our opportunities.
BT_PM 1.15 Discuss the pharmacokinetic and clinical implications of different routes of administration for commonly used opioids, including the oral, transdermal, subcutaneous, intramuscular and intravenous routes, and with particular reference to fentanyl, morphine, methadone, tramadol and codeine
Fentanyl undergoes significant first pass pulmonary uptake and metabolism. TRUE/FALSE
The cytochrome P450 3A4 (CYP3A4) is predominantly responsible for the metabolism of Alfentanil. TRUE/FALSE
Alfentanil undergoes extensive hepatic metabolism that demonstrates extensive interindividual variability TRUE/FALSE
The bioavailability of sublingual buprenorphine is similar to that of parenteral buprenorphine TRUE/FALSE
Epidural fentanyl undergoes a biphasic absorption pattern TRUE/FALSE
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