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35 Cards in this Set
- Front
- Back
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Rifampin MoA
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Inhibits B-subunit of DNA-dependent RNA polymerase
--> blocks transcription |
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Rifampin spectrum specific (3)
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Excellent activity vs Staph (+MRSA/MRSE), strep, M. tuberculosis
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How is resistance with Rifampin
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Resistance occurs easily with monotherapy and therefore this drug is always used in combination
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Does rifampin penetrate tissue well?
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Yes, rifampin has high tissue penetration
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Rifampin route
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IV/PO 300 mg q12h or 600 mg daily
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How is rifampin used and what is it used for?
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Used only in combination
-TB: as part of a 3-4 drug regimen -Staphylococcal infections: endocarditis, osetomyelitis, device infections |
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Rifabutin class and use
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Rifamycin
PO 300 mg daily TB, M. avium treatment/ppx |
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Rifaximin class and use
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Rifamycin
200 mg TID Traveler's diarrhea, C. dif |
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Rifapentine class and use
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Rifamycin
600-900 mg weekly TB |
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Trimethoprim/Sulfamethoxazole MoA
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Bactrim
MoA- interferes with folate synthesis -SMX: inhibits dihydropteroate synthetase -TMP: inhibits bacterial dihydrofolate reductase |
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TMP/SMX dose and route
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IV 15 mg/kd/d divided q6h (TMP)
PO 80/400 - 160-800 mg q12h (80 and 160 are TMP) |
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TMP/SMX specific spectrum (5)
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Good activity against
Staph (MRSA), H. influenzae, S. maltophilia, Listeria, Pneumocystis jirovecii |
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What is TMP/SMX's activity against Pneumococci? Enterobacteriaceae?
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Moderate activity for both
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Is TMP/SMX used empirically?
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No due to high resistance
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What drug is treatment of choice for Pneumocystis jirovecii infections and ppx?
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TMP/SMX
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What drug is treatment of choice for S. maltophilia infections?
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TMP/SMX
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What are the clinical uses for TMP/SMX
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Uncomplicated UTI
bacterial prostatitis RTI SSTI Increasingly for community associated MRSA |
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Nitrofurantoin MoA
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Binds to ribosomal proteins to block translation and inhibit bacterial respiration and pyruvate metabolism
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Nitrofurantoin spectrum (specific (1) and general)
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Enterococcus and most gram negative except Proteus
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What is the dose form of nitrofurantoin?
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PO 50-100 mg q6h or 100 mg q12h (macrocrystal)
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Uses of nitrofurantoin?
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Ppx and treatment of UTI
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What dysfunction do you need to look for when considering nitrofurantoin?
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Renal dysfunction. Low urine concentrations and increased adverse effects occur in renal dysfuntion
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What is an interaction with TMP/SMX that can cause increased bleeding?
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Warfarin
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How does TMP/SMX affect the CYP system?
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Inhibits hepatic metabolism of drugs such as Glipizide, PHT, repaglinide, rosiglitazone
TMP- CYP2C8 SMX- CYP2C9 |
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What is the interaction between TMP/SMX and cyclosporine
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TMP/SMX increases the metabolism of cyclosporine
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How does TMP/SMX affect renal tubular secretion?
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Inhibits renal tubular secretion
Increases amantadine, dapsone, dig, MTX |
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How does TMP/SMX affect protein binding?
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TMP/SMX displaces protein binding
Increases free sulfonylurea and MTX concentrations |
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T/F TMP/SMX has additive inhibiton of dihydrofolate reductase with drugs such as azathioprine, MTX, or pyrimethamine
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True
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What CYPs does Isoniazid inhibit?
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2C9, 2C19, 3A4
increases PHT, CBZ, diazepam, and warfarin |
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Why do we want to avoid high doses of APAP with isoniazid?
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Isoniazid increases APAP toxic metabolites
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We know that rifampin has a ton of interactions.. and is a potent INDUCER of cyp. Name some of the commonly encountered interactions (6)
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-Azole antifungals- Itra/keto/voriconazole should not be used.. fluconazole should be decreased by 50%
-Cyclosporin/tacro/sirolimus- narrow therapeutic index; monitor -Warfarin- monitor INR frequently -OC- documented failures -HIV antivirals- use rifabutin instead -Statins- double or trible the statin dose (don't have to worry about pravastatin) |
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When should sulfa abx be avoided in pregnancy?
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During the last month as it increases the risk of kernicterus in the infant
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What is one of the most common reasons for discontinuation of rifampin?
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Skin rash
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What antibiotic is known for discoloration of tears, sweat, urine, and other body fluids?
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Rifampin
can discolor contacts permanently |
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Do we need to worry about hepato or nephro toxicity with rifampin?
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Liver dysfunction/ hepatitis
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