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Pharmacology II > Lecture 22: Inhibitors of Protein Synthesis II > Flashcards

Lecture 22: Inhibitors of Protein Synthesis II Flashcards

1
Q

what is the mechanism of action of tetracyclines

A

Inhibition of protein synthesis by inhibiting 50s ribosomes and prevent access of aminoacyl TNRA to receptor site on mRNA-ribosome complex

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2
Q

Are tetracyclines bacteriostatic or bacteriocidal

A

Bacteriostatic

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3
Q

Are tetracyclines narrow or broad spectrum

A

Broad

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4
Q

Tetracycline have antimicrobial activity against what organisms

A

Gram positive and negative aerobes, anaerobes, Ricketssia (such as Anaplasma, Haemobartonella), spirochetes, mycoplasma clamydiae and some protozoans

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5
Q

Uptake of tetracyclines is ___dependent so they poorly penetrate ___

A

Oxygen, anaerobes

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6
Q

What are some uses for tetracyclines/ which ones in large animals

A

Tetracycline, chlortetracycline and oxytetracycline are used in treatment of local and systemic bacterial, chamydial, rickettsial and protozol infections in cattle, swine and sheep and as feed additives/ growth promoters in cattle, swine and poultry

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7
Q

What are some uses for tetracyclines in small animals/which ones

A

Doxycycline, minocycline, and tetracycline used for respiratory and urinary tract infections in dogs and cats, specific therapy for Boreilla (Lyme), brucella, haemobartonella, adn Ehrlicha

Also tx coccidiosis in birds

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8
Q

What tetracyclines have shown to be effective in abscesses in cats that don’t respond to B-lactams

A

Doxycycline and minocycline

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9
Q

Tetracyclines treat what special condition in foals and what is MOA

A

Contracted tendons in foals, inhibit the collagen based contraction in myofibroblasts

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10
Q

What is the drug of choice in treating tick borne diseases in animals

A

Doxycycline

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11
Q

What tick borne diseases does doxycycline tx in cats

A

Mycoplasma and chlamydophilia Felis

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12
Q

What tick borne diseases does doxycycline tx in dogs

A

Ehrlichia canis

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13
Q

What drug is often added to heart worm tx against Wolbachia

A

Doxycycline

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14
Q

Oral and parentally administered tetracyclines should be avoided in ___ due to danger in disrupting ___ or __ microflora

A

Horses, ruminal or colonic

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15
Q

Divalent and trivalent cations impair absoprtion of tetracyclines therefore ___, ___ and ___, should be avoided 3hrs before and after oral adminsitration

A

Milk, antacids, iron salts

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16
Q

What tetracyclines are more lipid soluble and distribute to CNS, eyes, and prostate

A

Doxycycline and minocycline

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17
Q

Which tetracycline is extensively metabolized by the liver

A

Minocycline

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18
Q

What is the route of elimination for doxycycline

A

Intestinal excretion

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19
Q

How long is the withdrawal period after intrauterine administration of oxytetracycline in cattle. What do they also recommend

A

28 days
Also recommends milk testing

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20
Q

What is the withdrawal period of IM or SQ administration of oxytetracycline in goats or sheep. And what is milk withdrawal time

A

28 days
Milk withdrawal 96 hrs

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21
Q

What is the withdrawal time for swine receiving oxytetracycline in feed or water

A

14 days

22
Q

What are some adverse effects of tetracyclines

A
  1. Nephrotoxicity
  2. Permanent staining of unerupted teeth due to tetracycline calcium-phosphate complex
  3. Superinfections
  4. GI effects in cats
  5. Anti-anabolic at high doses—> elevated BUN
23
Q

Oral tetracyclines should not be used long term in herbivores because of ___

A

Serious effects on ruminal digestion

24
Q

What tetracyclines don’t cause Nephrotoxicity and why

A
  1. Doxycycline- intestinal excretion
  2. Minocycline- metabolized by liver
25
Q

What is the mechanism of action of chloramphenicol and florfenicol

A

Binds 50S subunit and inhibits protein synthesis

26
Q

Is chloramphenciol bacteriostatic or bacteriocidal

A

Bacteriostatic, but can be bacteriocidal against certain meningeal pathogens such as H. Influenza, N. Meningitis, and Streptococcus pneumonias

27
Q

Why can chloramphenicol have negative effects on humans (MOA) and what are they

A

Mammalian mitochondria contain 70S ribosomes and chloramphenicol binds 50s subunit of bacterial 70s ribosomes, so chloramphenicol can cause dose-dependent bone marrow depression and gray syndrome due to inhibition of protein synthesis in host mitochondria

28
Q

What drug is illegal to use in food producing animals due to residue induced toxicity in hormones, aplastic anemia is fatal result

A

Chloramphenicol

29
Q

What is chloramphenicol used for

A

Used in dogs, cats, birds and horses for local and systemic infections inducing CNS, respiratory and ocular infections caused by anaerobes and Salmonella spp.

30
Q

What is florfenicol used for

A

Approved in cattle and swine for tx of respiratory diseases and foot rot in cattle

Available as drinking medication in swine

31
Q

T or F: chloramphenicol is distributed to CNS and eyes

A

True

32
Q

What is the T1/2 life in dogs and cats for chloramphenicol and why is it different

A

Dogs: 1-1.5hrs
Cats:4-5hrs
Due to glucuronidation metabolism

33
Q

T or F: florfenicol is distributed to CNS

A

True

34
Q

What is the t 1/2 life of florfenicol in cattle

A

18 hours

35
Q

How is florfenicol excreted

A

2/3 is excreted in urine and 1/3 metabolized by liver

36
Q

What are some adverse effects of chloramphenicol

A
  1. Anemia in humans and animals due to inhibition of iron uptake present in erythropoietic cells in bone marrow
  2. Fatal aplastic anemia in humans
  3. Iatrogenic endotoxicosis- rapid killing of gram negative bacteria
37
Q

Ionophores are antibiotics derived from ___ primarily used in poultry and swine for ___ and ___

A

Streptomyces, feed efficiency and anticoccidial activity

38
Q

What is the net effect of monesin/ MOA

A

Transmembrane exchange of sodium ions for protons—> elimination of membrane potential and active transport

39
Q

How do ionophores effect rumen/ what is their MOA there

A

Ionophores selectively affect gram + organisms, resulting in shift to gram - populations, increases production of propionic acid, decreases acetic and butryic acid production by rumen bacteria. This change in VFA increases feed efficiency by reducing bacterial energy losses to CO2 and methane, thereby increase energy content per unit of feed

40
Q

What are the uses for monesin, losalocid and laidlomycin

A

Administered as premixes or medicated feed for growth promotion, feed efficiency and control of coccidiosis in cattle and broiler chickens

41
Q

What are the uses for salinomycin and narasin

A

Administered as medicated feeds to broiler chickens to prevent coccidiosis

42
Q

What species are Ionophores particularly toxic in and why

A

Horses, absorption is more complete and metabolism is slower in monogastrics

43
Q

What are the signs of acute intoxication of ionophores in horses

A

Colic, sweating, incoordination, muscle weakness, elevated HR, dark urine, kidney failure, respiratory distress and going down

44
Q

What are the 3 important points in the veterinary feed directive

A
  1. Limit antibiotic use for therapeutic uses instead of production purposes
  2. Recommend drug manufactures voluntarily stop labeling drugs as “promoting animal growth”
  3. Extra label use of antibiotics requires a VPCR before compounding
45
Q

What new class of synthetic antibiotics are known as flurinated oxazolidinones

A

Linezolid

46
Q

What do linezolids have activity against

A

Aerobic gram positive organisms

47
Q

What is the mechanism of action for linezolid

A

Inhibits bacterial protein synthesis by interfering with translation

48
Q

How is linezolid metabolized

A

Oxidation- spontaneously breakdowns

49
Q

What are some adverse effects of linezolid

A

Interaction with MAO inhibitors

50
Q

What are some uses for linezolid

A
  1. Bacterial pneumonia
  2. Skin infections
  3. Vancomycin resistant enterococcal infections
  4. Methicillin resistant staphylococci (MRSA)
51
Q

What are some drugs used to tx oropharyngeal anaerobic infections and lung abscess

A
  1. Clindamycin
  2. B-lactam/lactamase inhibitor
  3. Metronidazole
52
Q

What are some drugs used to tx GI or female pelvic anaerobic infections (B. Fragillis often)

A
  1. Metronidazole
  2. Carbapenems
  3. Moxifloxacin

Pharmacology II (34 decks)

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