L2 ( CYP 2C9) Flashcards
True or false?
CYP 2C9 enzyme responsible for metabolism of the following drugs :
1️⃣Anti-diabetic agents (tolbutamide, glimepiride, glipizide, glyburide, nateglinide)
2️⃣Anticoagulant: warfarin
3️⃣Anticonvulsant: Phenytoin
4️⃣NSAIDS (diclofenac, ibuprofen,
indomethacin, naproxen, piroxicam)
5️⃣Antihypertensive drug: losartan
True ✅
True or false?
CYP2C9 also metabolizes endogenous substrates, such as arachidonic acid and linoleic acid.
True ✅
True or false?
CYP2C9 metabolizes narrow therapeutic index drugs such as warfarin, phenytoin.
True ✅
True or false?
Warfarin is a racemic mixture, and the S-isomer, which possesses about three times the anticoagulant effects of the R-isomer.
True ✅
True or false?
S-isomer is metabolized by CYP2C9, whereas R-warfarin is metabolized by CYP1A1, CYP2C19, and CYP3A4.
True ✅
True or false?
CYP2C92 and CYP2C93 are the two most common CYP2C9 variants in whites, and both exhibit single-amino-acid substitutions at positions critical for enzyme activity.
True ✅
Complete the sentence:
90% reduction in S-warfarin clearance was reported in CYP2C93 freaddicity
homozygotes compared with subjects homozygous for the wild-type (1) variant, requiring ……….
dose reduction to 0.5 mg/day in a report of a CYP2C9*3 homozygote initially given usual doses of warfarin.
Complete the sentence:
Patients having a CYP2C9*2 or *3 allele are significantly prone to experience a bleeding event and prolonged hospitalization due to …..
unstable anticoagulation when compared with the wild-type.
True or false?
More recently, the CYP2C9*8 allele was shown to reduce warfarin clearance and dose requirements.
True ✅
True or false?
Ultra rapid CYP2C9-mediated metabolism has also been recently reported resulting in higher dosage requirements of warfarin and phenytoin, and the molecular mechanism is currently under investigation.
True ✅
True or false?
Both CYP2C9 and CYP2C19 metabolize phenytoin, CYP2C9 is responsible for the major pathway of phenytoin metabolism (80–90% of
its elimination).
True ✅
True pr false?
Since phenytoin exhibits a narrow therapeutic range with a concentration-related toxicity, small changes of CYP2C9 activity can lead to nervous system intoxication.
True ✅
Complete the sentence:
Patients carrying at least one variant of defective CYP2C9 allele required …..
a 30% lower phenytoin maintenance dose than the patients carrying CYP2C91/1 genotype.
True or false?
Individuals having CYP2C93/3 exhibited a 3-fold increase in half-life and a 4-fold increase in AUC compared with individuals having
CYP2C91/1.
True ✅
True or false?
The importance of CYP2C9 in the metabolism of phenytoin was
evidenced by several case reports of individuals who had a homozygous mutation for CYP2C9*6 null allele, indicating that these individuals have no active CYP2C9 protein; They were taken to the emergency department with severe phenytoin toxicity.
True ✅
