5 (Student Presentation) - Anti tuberculosis: Ethionamide

Question 1

Pharmacokinetics of Ethionamide

Answer 1

Absorption: Not subjected to first pass metabolism in GIT, bioavailability ~100%

Distribution: 30% bound to proteins, with rapid and wide distribution

Metabolism: Metabolized extensively in the liver (Active metabolite: Ethionamide sulphoxide)

Excretion: <1% in urine as ethionamide

Question 2

MoA of Ethionamide

Answer 2

EthA catalyze NADPH- and O2 dependent monooxygenat ion of ETH –> ETH activated into thioamide S-oxide (ETH-SO) –> ETH-SO binds to NAD-, then forms ETH-NAD adduct –> Competitive inhibition of InhA –> Disruption of mycolic acid synthesis –> Cell lysis

Question 3

Common side effects of Ethionamide

Answer 3

GIT disturbances (nausea, vomiting, diarrhea, stomach pain, loss of appetite), metallic taste in mouth, headache, dizziness, ulcers in mouth, trouble swallowing, drowsiness