C.18

Question 1

Metronidazole

Answer 1

MOA: Bactericidal, Acts by producing toxic intermediary metabolits (reduction of N2O group = nitroso group formation) in anaerobic conditions;
Spectrum:
-Anaerob bacteria and protozoons Including: B. Fragilis, Clostridium,
-Protozoons: Trichomonas, G. Lamblia, E. histolytica;
Pharmacokinetics: Good absorption, Wide distribution → CNS, Abscesses, Metabolized in the liver, excreted with bile;
Dose: 3xday;
SEs: GI (nausea, metallic taste, dirrhoea, stomatitis), Neuologic (headache, dizziness, ataxia, paresthesia, peripheral neuropathy), Alcohol-intolerance (,,Disulfiram-like effect´´)

Question 2

Nitrofurantoin

Answer 2

Structure: Similar to nitroimidazoles;
MOA: converted to electrophilic intermediate which inhibits TCA cycle and DNA, RNA and protein synthesis, Weak bacteriostatic property;
Pharmacokinetics: Good absorption, rapid renal excretion → acts only in the urinary tract (Urine acidification enhances drug activity; Dose adjustment in renal impairment);
ROA: P.O;
IND: Urinary antiseptic (→ NOT proteus and pseudomonas), Uncomplicated lower UTIs;
SEs: Not normally, mainly with prolonged treatment or renal impairment! GI distress, Skin rash, Pulmonary infiltrate, Phototoxicity, Acute hemolysis in G6PD deficient patients:

Question 3

Fidaxomicin

Answer 3

MOA: Bactericidal, Binds sigma subunit of RNA polymerase → inhibit DNA-dependent RNA polymerase;
Spectrum: Narrow = Gram (+) anaerobes→ lower risk for resistance development!!;
ROA: P.O → poor systemic absorption→ reaches high intraluminal concentration!;
IND: Pseudomembraneous enterecolitis;
Extra: Less relapse compared with oral vancomycin!;
SEs: Negligible due to limited absorption

Question 4

Rifaximin

Answer 4

MOA: Bactericidal, Inhibits DNA-dependent RNA polymerase by binding to Beta-subunit;
Spectrum: Broad→ Gram (+), Gram (-), Aerobes, Anaerobes;
ROA: P.O; Pharmacokinetics: Poor Oral bioavailability, Induce CYP3A4; T1/2: 6 hrs;
IND: Traveler´s diarrhea (→ casued by E.Coli), IBS, hepatic encephalopathy (→ kills deaminating enteric bacteria → decreased production of Nitrogenous compounds), Diverticular disease

Question 5

Fosfomycin

Answer 5

MOA: Bactericidal, Inhibits bacterial enzyme enolpyruvate transferase → blocking synthesis of N-acetylglucosamine (NAG) (precursor of bacterial cell wall synthesis);
Spectrum/IND: Gram (+) and Gram (-), Used in treatment of uncomplicated lower UTIs in women (oral, single dose), Cystitis caused by susceptible strains of Escherichia coli and Enterococcus faecalis;
Pharmacokinetics: Renal elimination - excreted unchanged, with urinary concentrations exceeding MIC’s for most urinary tract pathogens, Penetrates biofilms + can alter biofilm structures;
SE: GI distress → Diarrhea;
ROA: P.O - Single dose! / Parenteral;
T1/2: 6 Hrs

Question 6

Hepatic encephalopathy

Answer 6

an often-temporary neurological (nervous system) disorder due to chronic, severe liver disease . A diseased liver struggles to filter toxins (substances created from the breakdown of food, alcohol, medications and even muscle) from the bloodstream