Antituberculotic Flashcards
how is TB transmitted
expelled when a persion with infectious TB sneezes, speaks, sings or coughs
what organism causes TB?
mycobacterium tuberculosis
Name the 6 first line antituberculosis drugs
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
- Streptomycin
- Rifabutin
What drugs do you use in combination to treat an active TB infection
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
*RIPE for treatment
multi-drug resistant TB has become resistant to what Abx
- Isoniazid
- Rifampin
extreme drug resistant TB has become resistant to which Abx
- Isoniazid
- Rifampin
- any Fluoroquinolone
- one injectible second line drug (capreomycin, kanamycin, amikacin)
what is the recommended regimen of treatment for a new smear or culture positive case of TB
- take the following for 2 months
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
- take the following for 4 months
- Isoniazid
- Rifampin
Which abx are used in the treatment of latent TB disease
- Isoniazid
OR
- Rifampin
what is the mechanism of action of Isoniazid? static or cidal
inhibits biosynthesis of mycolic acid (in cell wall)
- bacteriostatic
- INH and Rifampin combo is bactericidal
toxicity of Isoniazid
- Hepatitis
- Peripheral neuritis (slow acetylators)
- Hemolysis (in patients with 6GPD deficiencty)
- Lupus-like syndrome
- CNS stimulation
*weight benefits of prophylaxis vs risk of hepatitis, especially in patients 35 years or older
route of administration of Isoniazid
oral
metabolism of Isoniazid
- via acetylation (liver)
- some people are “rapid” or “slow” metabolizers
what is the MOA of Rifampin
inhibits DNA dependent RNA polymerase
which antiTB drug is effective against leprosy
Rifampin
spectrum of coverage of Rifampin
most G+ and some G-
toxicities of Rifampin
- Hepatic enzyme induction- potent inducer of cytochrome P450
- harmless orange color to urine, sweat, tears, and contact lenses
- decreases effectiveness of birth control
Rifampin is not recommended for which patient population
HIV treated individuals
MOA of Ethambutol? static or cidal
- inhibits arabinosyl transferases (involved in synthesis of arabinogalactan in the cell wall)
- bacteriostatic
important distribution of Ethambutol
gets into the CNS
toxicities of Ethambutol
- decrease of visual acuity
- loss of green-red perception (usually reversible upon discontinuation of drug)
- not recommended in children below age 13 yo
Inside what structure are mycobacterium tuberculosis in the body
- facultative intracellular parasite
- usually of macrophages
when does Pyrazinamide become active?
active at acidic pH - optimal for Mtb within macrophages
Pyrazinamide has the greatest activity against what stage of Mtb
dormant organisms
toxicities of Pyrazinamide
hepatic dysfunction
MOA of streptomycin? static or cidal
- protein synthesis inhibitor (30S ribosome)
- bactericidal
toxicities of Streptomycin
- otoxicity
- nephrotoxicity
MOA of Rifabutin
inhibits DNA dependent RNA polymerase
When is Rifabutin used
- REPLACES Rigampin in HIV-TB co-infected individuals to avoid drug reactions
- less potent inducer of P450 enzymes
List the second line antiTB agents (lower potentcy and/or greater toxicity)
- para-aminosalicylic
- ethionamide
- capreomycin
- amikacin
- fluoroquinolones
Mycobacterium avium complex (MAC) involves which two bacteria
- M. avium
- M. intracellulare
treatment of Mycobacterium avium complex (MAC)
antimicrobials for 12 months
- either clarithromycin or azithromycin
- I.V. amikacin if resistant to clarithromycin
- ethambutol
- Rifabutin, Rifampin, Or Ciprofloxacin
Treatment of mycobacterium leprae in PB leprosy patients: 1-5 patches
- treat with the following for 6 months
- Rifampin
- Dapsone
Treatment of mycobacterium leprae in MB leprosy patients: > 5 patches
- treat with the following for 6-12 months
- Rifampin
- Dapsone
MOA of Dapsone (the most widely used and least expensive drug)
similar to sulfonamides
- PABA antagonist
route of administration of Dapsone
oral
toxicities of Dapsone
nasal obstruction: improves in 3-6 months
Patients with leprosy can develop erythema nodosum leprosum (ENT). What drug would you add to the treatment regimen for moderate to severe ENL?
Thalidomide
Thalidomide has orphan drug status for which conditions
- lepromatous leprosy
- treatment of mycobacterium infections
toxicities of Thalidomide
teratogenic
*should not be given at any time during pregnanct
