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Mycobacterial Infections (Exam 4)
Mycobacterial Infections
9
Pharmacology
Graduate
11/03/2010

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Cards

Term
Clofazimine
Definition
treat leprosy
-alternative to dapsone
PK: has erratic absorption rate, stored in skin and reticuloendothelial tissues -> slowly released
USE: sulfone-reistant leprosy, sulfone intolerant pts
SE: skin discoloration from red brown to nearly black
Term
Dapsone
Definition
treat leprosy
MOA: closely related to sulfonamides and comp. inhibit folate synthesis
PK: well absorbed from GI, widely distributed, eliminated in urine
USE: initial therapy combined with rifampin and clofazimine
TOX: generally well tolerated, hemolysis (pts with G-6-PD deficiency
Term
Erythromycin, Azythromycin, Ciprofloxacin
Definition
drugs to treat atypical mycobacterial infections
Term
P-Aminosalicylic Acid
Definition
2nd line drug-treat TB
-folate synthesis antagonist
SE: GI irritation and hypersensitivity rxn
Term
Streptmyocin
Definition
1st line drug-treat TB
MOA: unclear
USE: M TB, M avium complex, M kansaii (always given in multidrug regime and treatment continued for several months)
PK: poor penetration into cells-effective mostly against extracellular TB; used when injectable (IM or IV) therapy recommended (TB meningitis, disseminated infection, when TB resistant to other drugs)
MOR: point mutation in rpsL gene (S12 ribosomal protein gene) or rrs gene (16S ribosomal protein gene) -> alter ribosomal binding site
TOX: dose-related ototoxicity and nephrotoxicity, vertigo, hearing loss; risk increased in elderly and pts with impaired renal function
Term
Ethambutol
Definition
1st line drug-treat TB
-bacteriostatic agent
MOA: inhibit mycobacterial arabinosyl tranferase enzymes, encoded by the embCAB operon -> polymerization of arabinoglycan (component of mycobacterial cell)
USE: given as daily dose with INH and rifampin, effective against most M TB strains
MOR: mutations resulting in overexpression of emb gene products or within emb structural gene
PK: well absorbed from GI, excreted in feces and urine, accumulates in renal failure and reaches CSF only during inflammation
SE: dose-related retrobulbar neuritis -> loss of visual acuity and red-green color blindness (disappears after discontinuation of drug), hypersensitivity to drug is rare
-contraindicated in children
Term
Pyrazinamide
Definition
1st line drug-treat TB
MOA: synthetic analog of nicotinamide, converted to pyranzinoic acid (active form) by mycobacterial pyrazinamidase (encoded by pncA)
MOR: mutations in pncA, decreased drug uptake
USE: combo with INH and rifampin in short course regmine (6 months) as sterilizing agent to prevent relapse
PK: well absorbed from GI, widely distributed
-no cross-resistance between this drug and other anti-TB agents
SE: hepatotoxicity, GI disturbances, hyperuricemia (not reason to stop txt unless develops gout)
Term
Rifampin
Definition
1st line drug-treat TB
MOA: analog of antibiotic rifamycin, binds to beta-subunit of bacterial DNA-dependent RNA polymerase -> inhibit RNA synthesis
USE: various bacteria, in combo with other drugs is effective in some atypical M infections and leprosy; as single drug-alternative to INH prophylactic tx for TB
MOR: point mutation in rpoB -> reduced rifampin binding to RNA polymerase
PK: well absorbed (oral admin), excreted into bile, penetrates most tissues and fluids and CSF
SE: SECRETIONS ARE RED ORANGE COLOR, proteinuria, rash, nephritis, jaundice, hepatitis; intermittent admin -> flu-like syndrome; strongly induces P450 enzymes
Term
Isoniazid (INH)
Definition
1st line drug-treat TB
MOA: acts only upon M, prodrug-activation by mycobacterial catalase peroxidase KatG -> forms complex with AcpM and KasA -> blocks mycolic acid synthesis and kills cell
MOR: over-expression of inhA gene, mutation/deletion of katG gene, promoter mutation resulting in overexpression of ahpC, mutations in kasA
PK: well absorbed (oral admin), widespread distrib. including brain and CSF
USE: chemoprophylaxis in individuals with greatest risk factors, young children, immunocompromised individuals; pyroxidine recommended for slow acetylators (neuropathy)
TOX: hepatitis, risk increases with age, greater risk in alcoholics, pregnancy and post-partum period
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