BOF: 43
A 36-year-old female is known to have migraine. She is
usually able to get relief by using paracetamol. She had given up smoking for
years but has begun to smoke 20 cigarettes a day and now complains that
paracetamol no longer relieves her headaches.
This is because:
a)
Smoking reduces cerebral blood flow
b)
Nicotine is a competitive inhibitor of paracetamol
c)
Smoking induces liver enzymes
d)
Smoking reduces blood flow to the intestine and thereby reduces
absorption of paracetamol
e)
Smoking increases renal clearance of paracetamol
Answer:
c)
Cigarette smoking reduces the efficacy of certain drugs or
makes drug therapy unpredictable. Pharmacokinetic interactions that cause
smokers to require a larger dosage of certain drugs are:
§
An increase in plasma clearance
§
A decrease in absorption
§
An induction of cytochrome P450 enzymes
§
A combination of these factors
Last Updated: 24/04/06
