LEC 20 - Inhibitors of Nucleic Acid Synthesis Flashcards Preview

Pharmacology II > LEC 20 - Inhibitors of Nucleic Acid Synthesis > Flashcards

Flashcards in LEC 20 - Inhibitors of Nucleic Acid Synthesis Deck (77):
1

When is nitrofurantoin most effective?

Acidic urine 

2

What specific organisms tend to be highly resistant to sulfa drugs? (5)

Ricketsia 

Fungi 

Molds 

Mycobacterium tuberculosis 

Spirochetes 

3

Therapeutic Use - Sulfadimethoxine 

Long acting 

More soluble + less toxic

4

How are sulfa drugs excreted from the body?

renal excretion of unchanged drugs + metabolites 

Via glomerular filtration + active secretion + passive tubular reaborption 

5

Therapeutic use - Orbifloxacin + Marbofloxacin

Dermal + Respiratory + Urinary infections - dogs and cats 

 

6

Why are sulfonamides safe for mammals?

Mammals require formed folic acid and do not require synthesis of it. 

7

How are fluoroquinolones distributed throughout the body?

Wide distribution 

Including CNS, bone, and prostate

8

Therapeutic use - Danofloxacin

Bovine respiratory infections 

Mannheimia species 

9

What are the sulfoamides derivitives of?

Beneze sulfanilamide

 Produced by substitution of the amino group 

 

10

What are the side effects of trimethoprim or ormetoprim?

Decrease in plasma levels of thyroid hormones

11

Why is rifampin combined with erythromycin?

Treatment of rhodococcus equi infections in foals 

12

What are the three sulfonamide mixtures that are used?

Sulfadiazine + trimethoprim 

Sulfamethoxazole + trimetoprim

Sulfadimethoxine + ormetoprim 

13

What are the side effects seen with sulfa drugs?

Renal crystalluria 

KCS 

Hypoprothrombinemia + Thrombocytopenia 

Arthritis 

Reduced sperm counts 

 

14

Therapeutic use - Orbifloxacin only 

Gram (-) infections in horses 

15

What is the specific mechanism of action for fluoroquinolones?

Inhibit bacterial DNA gyrase + topoisomerase enzymes that control DNA supercoiling 

16

How do sulfa drugs cause renal crystalluria?

Precipitaion of sulfonamides in neutral or acidic urine 

Occurs more often with large or prolonged doses w/ inadequate water intake 

17

How is nitrofurantonin used?

lower urinary tract infections in dogs and cats

18

What are the three other drugs that interfere with nucleic acid synthesis but do not belong to a group?

Metronidaole 

Rifampin 

Nitrofurantoin

19

Therapeutic use - Enrofloxacin

Dermal + respiratory + urinary infections 

in 

Dogs - cats - brids 

(only respiratory infections in cattle) 

20

What can metronidazole be combined with? Why?

Clindamycin 

Prevent pseudomembranous colitis 

21

What protozoas does metronidazole act against?

Giardia 

Trichomonas

22

What does enrofloxacin work for in regards to bovine respiratory disease?

M. haemolytica 

P. Multocida 

H. Somni 

M. Bovis 

23

How is rifampin distributed throughout the body?

Wide distribution to cells and tissues

24

How is rifampin excreted?

Primarily in the bile 

up to 30% can be excreted in the urine 

Parent drug can also be excreted 

25

How are potentiated sulfa drugs handled in the body?

Widely distributed 

Transcellular fluid = 80% of plasma concentration 

Bind to albulmin 

26

How is rifampin adminstered?

TID 

Foals + Dogs + Cats

27

What adverse effects are seen with fluoroquinolone use?

Reversible erosion of articular cartilage in dogs and foals 

Retinal degeneration in cats 

28

What is the protocol for Enrofloxacin use in cattle?

Can be given for up to 5 days in cattle 

Or 

Single high dose for respiratory infections 

29

What type of inhibtion does sulfa drugs cause with PABA?

Competitive

30

What are the adverse effects of rifampin?

Hepatotoxicity with pre-existing liver disease 

Re-oranged colored urine, sweat, and saliva but not harmful

31

How two drugs can be mixed with sulfa drugs to make potentiated sulfonamides?

Trimethoprim 

Ormetoprim 

32

What is the specific mechanism of rifampin?

Inhibits DNA-dependent RNA polymerase 

Prevents initiation of RNA synthesis 

33

What happens with elmination rate with rifampin after repeated doses? why?

increased elimination 

induces microsomal enzymes

34

Sulfonamides (5)

Sulfamethazine 

Sulfadimethoxine 

Sulfachlorpyridazine 

Sulfacetamide

Sulfasalazine 

 

35

What happens to the bacteria if folic acid is decreased?

Cannot multiply, grow, and survive 

36

How does elimination of the parent drug and metabolite differ with rifampin?

Parent drug is reabsorbed in the gut while the metabolite is not

37

How can nitrofurantoin be adminstered?

Ointment 

Powder 

Water-soluble wound dressing 

38

What do potentiated sulfa drugs allow for?

Sequential blockade of folate synthesis 

39

How is sulfasalazine processed in the gut?

Cleaved into sulfapyridine + 5-ASA via the gut bacteria 

40

How are fluoroquinoles metabolized?

Hepatic metabolism

41

Where do potentiated sulfa drugs tend to concentrate in the body?

Prostate, making it a good therapy for praostatitis 

42

What is different about sulfa drug metabolism in dogs?

There is no acetylation 

43

What type of bacteria tend to be resistant to fluoroquinolones?

Anaerobes 

 

44

What type of respiratory infections in cattle does danofloxacin work for?

M. Haemolytica 

P. Multocida 

45

What breed of dog is most susceptible to arthritis from sulfa drugs? what is the most common drug that causes this?

Dobermans 

Suldasalazine

46

Therapeutic Use - Sulfasalazine 

Enteric sulfa drug 

Colitis + IBD in dogs and cats 

 

47

How does resistance against fluoroquinolones occur?

DNA gyranse 

Topoisomerase 

mutations 

48

How are fluoroquinolones excreted?

Parent drug (15 to 50%) 

and metabolites excreted in bile and urine 

49

Why is rifampin combined with antifungal agents?

Treat fungal infections like aspergillous or histoplasmosis in dogs and cats with CNS infections

50

Therapeutic Use - Sulfamethazine

Cattle + Sheep + Swine 

 

51

What so the metabolites of sulfasalazine do?

Sulfapyridine = antibacterial agent 

5-ASA = anti-inflammatory 

52

How is the Rifampin metabolized?

Liver 

Metabolite is antibacterial as well 

53

What is the structure of sulfasalazine?

Linked to a molecule of 5-ASA 

 

54

What is PABA important for?

Intergral part of folic acid synthesis

55

What is the use of metronidazole?

Dogs, horse, + cats = severe infections caused by anaerobic pathogens 

most importantly - brain abcesses + pelvic/genitourinary tract/respiratory infections 

56

When are sulfoamides bactericidial?

Urinary tract infections due to the fact that the drug concentrates there and reaches high enough levels

57

Therapeutic Use - Sulfachlorpyridazine 

Rapidly absorbed + excreted 

Orally in Cattle under 1m 

Swine - respiratory + enteric infections (colibacillosis) 

58

Fluoroquinolines (5) 

Enrofloxacin 

Danofloxacin 

Diflozacin 

Orbifloxacin 

Marbofloxacin 

59

How is nitrofurantoin processed in the body?

Reduced by bacteria to reactive intermediates that inhibit nucleic acid synthesis 

 

60

What is the specific mechanism of action for metronidazole?

Anaerobic bacteria + protozoa takes up drug 

Reduces to cytotoxic metabolite = DNA disruption 

 

61

How are potentiated sulfa drugs adminstered?

Orally 

Injectables 

62

How are potentiated sulfa drugs metabolized in the body?

Via actylation + glucuronide conjugation

63

What organism is metronidazole most bactericidal against?

obligate anaerobes

64

What is Rifampin bactericidal against?

Mycobacteria 

Gram + pathogens 

65

What adverse effects are seen with Enrofloxacin specifically?

Seizures in dogs who are on phenobarbital 

66

What groups of bacteria do sulfa drugs kill?

Gram positive and negative

67

What is folic acid important for?

Purine + DNA synthesis 

68

What are the three groups of drugs that interfere with nucleic acid synthesis?

Sulfonamides 

Fluoroquinolones

Others...

69

Therapeutic use - Difloxacin 

Dermal + Respiratory + Urinary infections in dogs 

Pasteurella 

70

Therapeutic Use - Sulfacetamide 

Only one prepared as a salt at neutral pH 

Opthalmic preparations

71

What is the protocol for Nitrofurantoin use in food-producing animals?

NOT ALLOWED

72

What is important so that sulfonamides have antibacterial action?

Free para-amino group is essenstial 

73

What does enrofloxacin work for in regards to swine respiratory disease?

A. Pleuropneumoniae 

P. Multocida 

H. Parasuis 

B. bronchoseptica 

M. Hyopneumoniae

74

What are the upsides to using potentiated sulfonamides?

Bactericidal 

Broader spectrum 

Reduced rate of resistance 

75

What is the protocol for fluoroquinolone use in food animals?

Extra label use is not allowed

76

How is danofloxacin used?

Single dose or twice 48 hours apart 

 

77

What specific organisms are highly sensitive to sulfa drugs? (8)

Pneumococci 

Escherichia coli 

Nocardia 

Actinomyces 

Chlamydia 

Pneumocystis jirovecii 

Some protozoa