WCVD Papich lectures Flashcards
Fluoroquinolones should not be mixed with what compounds because they can chelate the drug and inhibit absorption?
metals - particularly iron, magnesium, aluminum; and calcium
Decreasing the stomach acidity inhibits oral absorption of what drugs as they are better absorbed in an acidic environment?
antifungal azoles (ketoconazole, itraconazole), pimobendan, oclacitinib
Decreasing the stomach acidity enhances absorption of what drugs because they are less stable in an acidic medium?
penicillins, omeprazole
Sucralfate contains what ingedient that can interfere with absorption of fluoroquinolones?
aluminum
What ingredients in antacid drugs can bind to tetracyclines and prevent absorption from the GI tract?
magnesium and calcium
Where are multi-drug resistance efflux pump (P-glycoprotein pump) located?
intestine, biliary tract, liver, kidney tubules, placenta, blood-brain barrier
What drugs inhibit the P-glycoprotein pump?
fluoxetine, paroxetine, itraconazole, ketoconazole, methadone, verapamil, quinidine, bromocriptine, tamoxifen, St. John’s Wort, erythromycin, pentazocine, carvedilol, cyclosporine, chlorpromazine, Grapefruit juice
Ketoconazole can cause drug interactions through its activity on what pathways?
inhibits P-glycoprotein AND cytochrome p450
Drugs that are substrates for P-glycoprotein
Doxorubicin, Vincristine, Vinblastine, Aldosterone, Cortisol, Dexamethasone, Methylprednisolone, Erythromycin, Cyclosporine, Ketoconazole, Itraconazole, Terfenadine, Phenothiazines, Tetracycline, Doxycycline, Levofloxacin, Loperamide, Morphine, Digoxin, Dilitiazem, Verapamil, Tacrolimus, Ivermectin, Amitriptyline, Ondansetron
What drugs increas the activity of P-glycoprotein? What effect does this have on other drugs?
rifampin, corticosteroids, phenobarbital – results in increased clearance of other drugs
What substances are cytochrome enzyme inducers?
phenobarbital, phenytoin, phenylbutazone, pentobarbital, diazepam, alcohol, chlorinated hydrocarbons, griseofulvin, estrogen, progestogens, diphenhydramine, rifampin, hyperthyroidism
What is a phase I reaction in the liver?
metabolize drugs to a more water-soluble compound - often oxidative reactions, but other reactions (reduction) can occur
What are phase II reactions in the liver?
conjugation reactions – e.g. conjugation with glucuronic acid; other conjugation reactions with amino acids, acetyl groups, and sulfate also are possible
Name inhibitors of cytochrome p450 enzymes
cimetidine, ketoconazole, organophosphates, quinidine, cyclophosphamide, ondansetron, cyclosporine, diazepam, loperamide, morphine, chloramphenicol, erythromycin, interferon, tetracycline, verapamil, propofol, vincristine, fluoxetine, ivermectin
Which drugs are most likely to cause a problem due to their role as a cytochrome p450 inhibitor?
ketoconazole, cyclosporine, chloramphenicol
Which drugs are most likely to cause a problem due to their role as a cytochrome p450 inducer?
rifampin, phenobarbital
T/F: Antibiotics administered to dogs and cats cause resistance in bacteria.
False - antibiotic exposure can SELECT for resistant bacteria
What are the most common bacteria producing resistant infections in small animals?
E. coli, Pseudomonas aeruginosa, Methicillin-resistant Staph spp., Enterococcus spp.
T/F: Administration of antibiotics can increase the shedding of drug-resistant fecal bacteria.
TRUE
T/F: Use of fluoroquinolones and cephalosporins has been linked to emergence of resistance in staphylococci in dogs.
False - use of specific drugs have not been associated with methicillin resistance but administration of ANY antimicrobial within 30 days of prior to infection was identified as a risk factor
Rifampin: Bacteriostatic or bactericidal?
bactericidal
Rifampin: MOA?
inhibits bacterial RNA polymerase
What is most common adverse effect of rifampin?
hepatoxicity
Adverse effects from doxycycline?
renal injury, intestinal disturbances, hepatic injury
T/F: All tetracyclines cause dental enamel discoloration.
False - doxycycline does NOT chelate with calcium
T/F: Aminoglycosides are equally effective against both gram-positive and gram-negative bacteria.
False - more effective against gram NEGATIVE bacteria
Vancomycin: Bacteriostatic or Bactericidal?
bactericidal
Vancomycin: MOA?
inhibits cell wall formation
Vancomycin: Adverse effects?
skin flushing, pruritus, tachycardia (related to histamine release); nephrotoxicity, ototoxicity
Linezolid: route of administration?
oral and IV - oral absorption is ~100%
What enzyme does linezolid inhibit?
mild, reversible inhibitor of monoamine oxidases A and B
Carbapenems: Bacteriostatic or bactericidal?
bactericidal
Disadvantages of imipenem?
inconvenience of administration, short shelf-life after reconstitution, high cost
T/F: Penicillins have little activity on gram negative bacteria.
True - even when combined with beta-lactamase inhibitors
Unique adverse effect of prednisolone in cats?
congestive heart failure
Why is acetaminophen more toxic to cats than dogs?
cats are deficient in glucuronidation enzyme (required for elimination of acetaminophen)
Unique adverse effect of voriconazole in cats?
neurologic/ocular problems
Why are slow-release tablets not well absorbed in cats?
shorter intestines - GI transit time variable
What drugs have a slower clearance in cats due to their glucuronidation deficiency?
aspirin, benzoic acid, acetaminophen, chloramphenicol, morphine, desmethyl tramadol (active metabolite of tramadol)
