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18 Cards in this Set
- Front
- Back
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First Line Tb Drugs |
Isoniazid Rifampin Ethambutol Pyrazinamide Streptomycin |
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Isoniazid MOA |
Prodrug requiring conversion by catalase peroxidase Inhibit synthesis of mycolic acid by inhibiting fatty acid synthetase Acts on intra and extracellular bacilli Bactericidal for actively growing tubercle bacilli |
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Isoniazid USE |
TB |
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Isoniazid ADVERSE EFFECTS |
Hepatotoxicity, peripheral neuropathy, hemolysis inpatients with G6PD deficiency Others: Pyridoxinedeficiency (VitB6) , SLE –like syndrome |
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Isoniazid DRUG INTERACTIONS |
Antacids: Isoniazid (INH) absorption Para-AminoSalicylic (PAS), Ethionamide: synergism |
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Isoniazid RESISTANCE |
inactivating mutation in the mycobacterial enzyme catalase-peroxidase, which convertsisoniazid into its anti-mycobacterial form. |
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Rifampin MOA |
Inhibitsinitiation of RNA synthesis by binding to DNA dependent RNA polymerasepreventingattachment of the enzyme to DNA, thus blocking initiation of RNA transcription. Potent tuberculocidal drugand can penetrate phagocytic cells thereforecan kill intracellularorganisms |
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Rifampin USE |
1.Gram (+) especially Staphylococcus (osteomyelitis and endocarditis) 2. Gram (-) N.meningitidis, N.gonorrhea, H. influenzae(type b) & Legionella 3. Chlamydia and some anaerobes |
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Rifampin ADVERSE EFFECTS |
Yellow orange sweat, tears and urine Hepatotoxicity |
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Rifampin DRUG INTERACTIONS |
Itacts as a hepaticP450 enzyme inducer
Steroids, oral contraceptives, digoxin,sulfonylureas, warfarin, ketoconazole, chloramphenicol: decrease efficacy of these drugs |
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Pyrazinamide MOA |
Is a prodrug; itmust be converted to its active form, pyrazinoicacid by the enzyme pyrazinamidase Inhibitmycolic acidsynthesis by inhibiting fatty acid synthase 1 - Bacteriostatic or bactericidaldepending on the concentration and susceptibility of the organism. -first-line drug used in conjunction with isoniazid and rifampin inshort-course |
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Pyrazinamide ADVERSE EFFECTS |
Arthralgias (40%),hepatitis (1-5%), hyperuricemia(provoke acute gout) |
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Pyrazinamide RESISTANCE |
dueto mutations in the pyrazinamidasegene,which result in the inability toconvert the prodrug intoits active form. |
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Streptomycin MOA |
Itinhibits protein synthesis by combining irreversibly with the 30S subunit ofthe ribosomes, found typically in prokaryotes. - Specifically, it binds with the12S protein involved in the initiation of protein synthesis. - penetrates poorly into cells & is active mainly against extracellular tubercle bacilli. |
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Streptomycin ADVERSE EFFECTS |
ototoxicity, nephrotoxic |
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Ethambutol MOA |
Itdisrupts arabinogalactan synthesis by inhibiting arabinosyl transferase. - Disruption of the arabinogalactansynthesis leadsto increased permeability of the cell wall -wellabsorbed from the GIT including CSF of patients with TB Meningitis |
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Ethambutol ADVERSE EFFECTS |
retrobulbar (optic) neuritis (dose-related),hypersensitivity |
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Ethambutol RESISTANCE |
from mutationsin the arabinosyltransferasegene |
