Topic 18-Metronidazole. Fidaxomycine. Rifaximin. Urinary antiseptic. Phosphomycine Flashcards
What is the mechanism of action of Metronidazole
It inhibits nucleic acid synthesis by disrupting the DNA of microbial cells.
Spectrum of Metronidazole
Anaerobe bacteria (including B. fragilis and clostridia) Protozoa (trichomonas, G. Lamblia, amoeba, gardnella vaginalis
Pharmacokinetics of Metronidazole
Administerd IV, oral, topical 3x day Good absorption wide distribution (CNS and abcesses) Metabolized in liver Excreted in bile
Clinical use of Metronidazole
Anaerobic or mixed intra-abdominal infection
Vaginitis
Clostridium dificile induced colits (IV or oral)
Brain abscesses
Extraluminal amebiases
Adverse effects of Metronidazole
Nausea, metallic taste, diarrhea
Headache, dizziness, ataxia, peripheral neuropathy
Alcohol interolerance (disulfiram life effect)
What are the two Urinary Antiseptics
Nitrofurans and Phosphomycin
What drug is included in the nitrofurans
nitrofurantoin
Mechanism of action of nitrofurantoin
The drug works by damaging bacterial DNA, since its reduced form is highly reactive.
Nitrofurantoin spectrum
E. coli and E. faecalis
Nitrofurantoin kinetics
High concentration in the urine
Indication of Nitrofurantoin
uncomplicated lower UTI (pregnancy, children, and cases of reistance)
Adverse effects of Nitrofurantoin
Vomiting
Acute hypersensitve pulmonary reaction
Neuropathies
What is the mechanism of action for Phosphomycin
Cell wall synthesis inhibitor and inhibits the first step in the formation of UDP-N-acetylmuramic acid
Spectrum of action for phosphomycin
broad spectrum
staph, klebsiella, proteus, e. coli
Pharmacokinetics of phosphomycin Administered Absorption Accumulates Indications
Oral or parenteral Good absorption Builds up systemically Accumulates in urine Behaves like urinary antiseptic -used in UTI -used in pregnancy -not children
What is the mechanism of action of rifaximin?
interferes with transcription by binding to the β-subunit of bacterial RNA polymerase
Spectrum for rifaximin
Gram positive (staph, strep, entero) Gram negaice (moderate action against intestine bacteria, but does not absorb from GI)
Administration of rifaximin
Oral
Indication for rifaximin
Hepatic encephalopathy, prophlyaxis before colorectal surgery, and acute enteritis and colitis
What is the mechanism of action of Fidaxomicin
Fidaxomicin binds to and prevents movement of the “switch regions” of bacterial RNA polymerase
Fidaxomicin
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