TB

Question 1

MOA of isoniazid

Answer 1

Inhibition of synthesis of mycolic acid of cell wall
Congener of pyridoxine

Not given alone
Bactericidal + bacterostatic
Can penetrate macrophages

Question 2

Pharmacokinetics of isoniazid

Answer 2

Oral 5mg/kg/d
Metabolism in liver: acetylation

Also given as prophylaxis.

Question 3

Toxicity of isoniazid

Answer 3

Insomnia restlessness, muscle twitches: give vit B12. 25-20mg/d
Hepatotoxic:jaundice
Inhibits metabolism of drugs
Hemolysis in G6PD deficiency

Question 4

MOA of rifampin/rifabutin/rifapentin

Answer 4

Oral
ENTEROhepatic recycling ,orange color

Blocks transcription by RNA polymerase

Rifapentin one dose weekly

Question 5

Toxicity of rifampin 10mg/kg/day

Answer 5

Orange fluids
Light chain proteinuria
Skin rash
Thrombocytopenia
Nephritis, liver dysfunction
Less than twice week: flu and anemia
INDUCES DRUG ENZYMES

Question 6

MOA of ethambutol

Answer 6

Inhibits arbinosyltransferases (inhibit synthesis of arabinogalactan)
Oral
Adjust dose in renal patients

Question 7

Toxicity of ethambutol 15mg/kg/day

Answer 7

Visual disturbances reversible
Optic neyritis
Retinal damage
Red green color blindness
Decreased visual activity

Question 8

Pyrazinoamide. 25-30mg/kg/day

Answer 8

Oral
Excreted in urine
Hepatotoxic

Arthralgia
Malaise
GIT upset
Hyperuricemia

Do not give in pregnancy (also streptomycin)