2. Antimycobacterial drugs Flashcards
1
Q
1st line Tuberculosis treatment
A
**“RIPE” - “4 FOR 2 AND 2 FOR 4”
R**
ifampin
Isoniazide
Pyrazinamide
Ethambutol
2
Q
Rifampin
A
- rifampin activated CYP P450
- rifampin bind to bacterial DNA dependent RNA polymerase deactivates it - this is where resistance will develop if used alone.
- Rifampin prophylactic monotherapy in close contacts of H. FLU and N. Meningitides
- Hepatotoxic in RIPE therapy
- Rifampin may produce orange body fluids
3
Q
Isoniazide
A
- INH inhibits cytochrome P450
- primary TB (often presents as middle lobe cavity)
- INH can be used alone to treat latent TB infections
- administration of INH and pyridoxine (vitB6) prevents peripheral neuropathy
-INH is activated by catalase-peroxidase (KatG)
(tail makes a G Shape)
- resistance to INH by downregulating KatG
- INH works at the bacterial cell wall inhibiting mycolic acid production
4
Q
Isoniazide
side effects
A
- INH promotes excretion of Vit B6 causing peripheral Neuropathy is caused by a Vit B6 deficiency
- INH may cause seizures
- hepatotoxicity associated with all RIPE therapy drugs
- INH causes an asymptomatic rise in aminotransferases
- INH may cause drug induced lupus
- INH may cause anion gap metabolic acidosis
- INH metabolized by the liver enzyme N acetyltransferase – slow acetylators have higher risk of side effects
5
Q
Ethambutol
A
- blocks arabinosyl transferase, inhibiting carbohydrate formation at the cell wall
- ethambutol is bacteriostatic
- optic neuritis (red -green blindness)
6
Q
Pyrazinamide
A
- moa same as Isoniazide
- pyrazinamide may cause hyperuricemia and needle shaped uric acid crystal formation
Yell ball on toe: pyrazinamide may precipitate gout attacks
- can be hepatotoxic
7
Q
2nd line treatment
A
**“C-PEARL” (F)
C**
ycloserine
- *P**as ( para amino salicylic acid)
- *E**thionamide
- *A**mikacin
- *R**ifabutin
- *L**inezolid
Fluoroquinolones
8
Q
Mycobacterium avium treatment
A
- a macrolide (azithromycin or clarithromycin) combined with ethambutol for MAC infections
- MAC is a common cause of disseminated disease in AIDS patients
- macrolide prophylaxis for MAC when CD4 <50
-Rifabutin
(may be added as a third agent to combat MAC infections)
- rifampin and rifabutin activate CYP450
9
Q
Mycobacterium Leprae - LEPROSY
A
Dapsone
Rifampin
Clofazamine
——————————————————————————-
- agranulocytosis
- hemolytic anemia in G6PD deficiency
- bite cells and Heinz bodies seen in RBC’s
- leonine facies seen in lepromatous leprosy