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Is chloramphenicol (CAP) static or cidal?
static. (cidal in high doses) do not use with penicillins or cephalosporins
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Is chloramphenicol useful in treating infections of the CNS, prostate, and globe of the eye?
yes
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How is chloramphenicol excreted?
liver metabolism - by conjugation using glucuronic acid, metabolites excreted in urine
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What common anticonvulsant drug completes with chloramphenicol for the specific liver enzymes that metabolizes them both?
phenobarbital
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If phenobarbital is given with chloramphenicol to patient, (both for the first time), do the blood levels of each drug decrease at a faster or slower rate than usual?
slower - toxicity may result
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Can we use chloramphenicol in food-producing animals? Why or why not?
no. CAP residues in human food can cause fatal suppression of human bone marrow - aplastic anemia
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What drug is related to and similar to chloramphenicol, is approved for use in cattle, and is not toxic to human bone marrow?
florfenicol
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Are lincosamides static or cidal?
either, depending on dose
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Are lincosamides good for bone infections?
yes
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Which lincosamides are used more in livestock?
- lincomycin - Lincocin
- pirlimycin - Pirsue
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Which lincosamide is used most in small animals?
clindamycin - Antirobe
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Clindamycin - Antirobe is especially known for treating what types of infections?
- dental infections
- some anaerobic infections
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What 3 drug types should not be used together due to competitive inhibition (all bind to the same site on the bacteria)?
- lincosamides
- erythromycin
- chloramphenicol
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Are macrolides static or cidal?
static. may be cidal if high dose
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Why are macrolides used PO instead of IM?
IM is painful
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Are macrolides useful in treating infections of prostate?
yes
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Are macrolides useful in treating infections of the CNS?
no
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What are some common side effects caused by administration of macrolides in small animals?
GI signs - vomiting, diarrhea, anorexia
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Why should you avoid use of macrolides in ruminants and adult horses?
causes severe diarrhea, may be fatal
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List 2 specific macrolides
- erythromycin
- tylosin - Tylan
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What is the earliest developed group of antimicrobial drugs?
sulfonamides
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What is the mechanism of action of sulfonamides?
interfere with folic acid synthesis of bacteria
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Are sulfonamides static or cidal?
static
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Are potential sulfonamides static or cidal?
cidal
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What is "potentiation" of a drug?
adding a substance to the drug to make it more effective
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What specific substances are added to sulfonamides to potentiate them?
- trimethoprim
- ormetoprim
- pyrimethamine
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What is the mechanism of action of trimethoprim and ormetoprim?
they interfere with bacterial folic acid synthesis at a different point than the sulfonamides do
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In general, are sulfonamides broad spectrum or narrow spectrum?
broad spectrum
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Can sulfonamides enter the prostate?
yes
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Should use of sulfonamides bea voided in patients with liver or kidney failure?
yes
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Why is it important to keep a patient on sulfonamides well hydrated?
to prevent crystal formation in the kidneys - causes damage
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What 2 things can you do to prevent crystal formation in the kidneys of a patient taking sulfonamides?
keep well hydrated, alkalinize urine
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List other problems that can occur in a patient taking sulfonamides.
- GI signs - vomiting, diarrhea, anorexia
- fever
- allergic reactions - skin problems
- KCS - keratoconjunctivitis sicca
- bone marrow suppression
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Are sulfonamides inactivated by pus and cellular debris? Why?
yes - bacteria can get folic acid from pus and cellular debris
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What is sulfasalazine broken down into in the intestines? What is sulfasalazine used for? Can it cause problems in cats? Why?
- sulfapyridine + aminoalicylic acid.
- used to treat inflammatory bowel problems
- yes, it can cause problems in cats due to the salicylate compound - related to aspirin - cats metabolize very slowly, toxic levels can occur
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List 2 specific commonly used potentiated sulfonamides.
- sulfadiazine + trimethoprim - Tribrissen, Ditrim
- sulfadimethoxine + ormetoprim - Primor
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List a specific sulfonamide commonly used to treat coccidiosis.
sulfadimethoxine - Albon
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What drug is commonly used to treat giardiasis?
metronidazole
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What other type of condition is metronidazole used to treat?
anaerobic enteric infections
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What does "teratogenic" mean?
causes birth defects
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Is metronidazole teratogenic?
yes
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What antimicrobial drug is used to treat Corynebacterium (Rhodococcus) infections in young foals?
rifampin
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What is rifampin's peculiar side effect?
turns urine, tears, sweat, and saliva reddish - orange
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What is the difference between systemic and topical fungal infections?
- systemic fungal infections affect the interior of the body - lungs, liver, CNS, blood - and are very serious
- topical fungal infections - dermatophytoses or ringworm - affect the skin and are usually more annoying than dangerous
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Which is the most nephrotoxic antifungal medication? Is it used for systemic or topical fungal infections?
amphotericin B - used for systemic infections
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How is the antifungal drug nystatin commonly used?
- in fungal infections (Candidiasis) in the crops of birds - PO.
- in topical combinations
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List 5 imidazole derivative antifungal drugs.
- ketoconazole
- itraconazole
- fluconazole
- miconazole
- clotrimazole
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What are the imidazole derivatives use for?
topical, deep, or systemic mycoses, or fungal infections
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Do the imidazole derivatives "kick in" immediately?
no - they take 5 - 10 days to become fungicidal after the beginning of administration to the patient
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How is ketoconazole used?
topically and PO for fungal infections
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What is ketoconazole's peculiar feature, and list its advantages and disadvantages
- inhibits steroidogenesis.
- since it inhibits corticol formation, it has been used to treat Cushing's disease.
- since it inhibits testosterone formation, it should be avoided in breeding males
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Is ketoconazole teratogenic?
yes
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What is miconazole used for? What is its human label name?
dermatophytes and Candida. Monistat
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What is grieseofulvin used for?
dermatophytosis - ringworm
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What is the difference between microsize and ultramicrosize griseofulvin?
the size of the particles making up the tablet. ultramicroszie is absorbed better by the patient.
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What can we do to improve the absorption of PO griseofulvin?
administer it with some fat - butter is good
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Is griseofulvin teratogenic?
yes
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How long does it take for griseofulvin to cure ringworm? Does the ringworm start improving immediately after medication is started?
- about 6 weeks
- no - ringworm usually looks worse before it starts to look better, due to loss of previously damaged hair
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List 1 topical antiviral drug. What is it used for?
idoxuridine - is used topically in ophthalmic ointment, to treat herpesvirus infection
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List 2 systemic antiviral drugs
- AZT - azidothymidine
- alpha - interferon
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List 3 drugs discussed in the antimicrobial section that are teratogenic
- metronidazole
- ketoconazole
- griseofulvin
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What 2 drugs discussed in the antibacterial section are not active in pus and cellular debris?
- aminoglycosides
- sulfonamides
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What 2 drugs discussed in the antibacterial section will diffuse into the CNS? Which is best?
- doxycycline
- chloramphenicol
- chloramphenicol is best
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What 3 drugs discussed int he antibacterial section will diffuse into the globe of the eye?
- doxycycline
- chloramphenicol
- quinolones (baytril)
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What 4 drugs discussed in the antibacterial section will diffuse into the prostate?
- doxycycline
- chloramphenicol
- quinolones (baytril)
- macrolides (erythormycin)
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It is important to keep the patient well hydrated to prevent crystal formation in the kidneys and urine of patients taking what 2 types of drugs?
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