(7) Antimicrobials: Antimicrobacterials (3.1-3.2) Flashcards
What drug regimen is most commonly used to treat active tuberculosis?
(1) Rifampin
(2) Isoniazid
(3) Pyrazinamide
(4) Ethambutol
* (And Vitamin B6)*
What are the two phases of treatment for tuberculosis?
(1) 4 drugs for 2 months
(2) 2 drugs for 4 months
What antibiotic can be used alone to treat latent tuberculosis infections?
Isoniazid
(“Remember, Isoniazid can be used isolated”)
MOA: Isoniazid
Inhibits the synthesis of mycolic acid
(Note: Pyrazinamide has the same MOA, but acts immediately upstream of INH)
What antibiotic is activated by catalase-peroxidase?
Isoniazid
Resistance: Isoniazid
Downregulation of Kat G
(Kat G ≡ catalase-peroxidase)
Adverse Effects (6) : Isoniazid
(1) Vitamin B6 Excretion
(2) ⇒ Peripheral neuropathy
(3) Seizures
(4) Hepatotoxicity
(5) Drug-induced lupus
(6) Inhibits CYP450
* (INH = Injury to Nerves and Hepatocytes)*
* (Note: All antimycobacterial agents can cause hepatotoxicity)*
Which antimycobacterial agent is metabolized by the liver enzyme N-acetyltransferase?
Isoniazid
(Slow acetylators ⇒ ↑ [INH]. There is a similar relationship with Procainamide, acetylation rates, and drug-induced lupus)
How do you prevent Isoniazid induced peripheral neuropathy?
Co-administer Vitamin B6
What abnormal lab value is expected after administering Isoniazid?
Increased aminotransferases
(Asymptomatic)
Which antimycobacterial drug can cause anion gap metabolic acidosis?
Isoniazid
Which antimycobacterial agent is a potent inducer of CYP450?
Rifampin
(Compared to Isoniazid which inhibits CYP450)
MOA: Rifampin
Inhibits DNA-dependent-RNA polymerase
When can Rifampin be used as a monotherapy?
PROPHYLAXIS for those exposed to:
(1) Neisseria meningitis
(2) Haemophilus influenzae
* (Otherwise, organisms quickly develop resistance)*
Which drug can turn bodily fluids orange?
Rifampin
MOA: Ethambutol
Inhibits arabinosyl transferase ⇒ inhibits carbohydrate polymerization
(“Think Ethambutol at the cell wall”)
Is Ethambutol bacteriostatic or bacteriocidal?
Bacteriostatic
Adverse Effect: Ethambutol
Optic neuritis
(Including red-green color blindness)
Which antimycobacterial agent may precipitate gout attacks?
Pyrazinamide
Which mycobacterial species constitute the Mycobacterium avium complex?
(1) Mycobacterium avium
(2) Mycobacterium intracellulare
Treatment: Mycobacterium avium complex
(1) Macrolide
(2) + Ethambutol
* (Rifabutin can be added as a third agent as well)*
CD4 count allowing: Mycobacterium avium complex
CD4 < 50
When treating tuberculosis in an HIV patient, what drug is used in place of Rifampin?
Rifabutin
(∵ It’s a weaker inducer of CYP450)
Reservoir: Mycobacterium leprae
Armadillo
Adverse Effects (2) : Dapsone
(1) Agranulocytosis
(2) Oxidative stress ⇒ Hemolytic anemia
* (Anemia in G6PD deficient individuals. Although not mentioned in the sketch, Dapsone is a Sulfa drug)*
What drug is only used during the treatment of lepromatous leprosy?
Clofazimine
Treatment: M. leprae
(1) Dapsone
(2) Clofazimine
(3) Rifampin
* (Clofazimine use only for the lepromatous form. Rifampin added for longterm therapy)*
