TB agents

Question 1

Isonazid

Answer 1

Oral, good cell penetration
liver metabolism via acetylation: fast and slow acetylators
MOA: inhibits the synthesis of mycolic acid
- bacteriostatic
Mode of resistance: KatG, InhA

AE: 
peripheral neuritis (give pyridoxine to prevent) 
hepatotoxicity in G6PD pts
SLE
CNS seizures

Question 2

rifampin

Answer 2

Oral, well absorbed via enterohepatic cycling, metabolites are orange coloured

MOA: inhibits DNA dependant RNA polymerase
- bacteriostatic
mode of resistance: RPOB

AE:

• orange ppl (metabolites)
• light chain proteinuria
• thrombocytopenia, nephritis, liver dysfunction, flu-like sx
• enzyme induct

Question 3

Ethambutal

Answer 3

oral well abosrbed, into CNS, renal elimation dose adjustment needed for renal failure

MOA: inhibits the synthsis of arabinogalactan (cell wall)
- bacteriostatic
MOR: embCAB

AE;
decreased visual acquity (red-green lost), optic neuritis, HA, peripheal neuritis , confusion

Question 4

Pyrazinamide

Answer 4

oral, well absorbed, good tissue penetration, partly metabolized, both metabolite and original drug is excreted in the urine
MOA: unknown
MOR: pncA

SE:
hyperurecemia, non-gouty polyarthralgia, hepatic dysfunction, photosensitivity, myalgia, GI irriation, porphyria, photosensisitvyt

Question 5

Stretomycin

Answer 5

parentaer, limited tissue penetration, renal excretion, does adjustment neccessary for renal failure

MOA: protein synthesis inhibt (30s)
- BACTERIOCIDAL
MOR: adenylation, phosphorylation of drug

AE:
Ototoxicity, nephrotoxicity, neuromuscular blockade, allergic skin rxn