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Pharmacology > Folate Antagonists, Quinolones, and UTI Agents > Flashcards

Folate Antagonists, Quinolones, and UTI Agents Flashcards

1
Q

2 types of folate antagonist drugs

A

Sulfonamides and trimethoprim/pyrimethamine

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2
Q

Sulfonamides MOA

A

Inhibit dihydrofolate synthesis (specifically dihydropteroate synthetase)

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3
Q

Trimethoprim and pyrimethamine MOA

A

Inhibitors of folate reduction (inhibit dihydrofolate reductase)

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4
Q

How do humans obtain folate?

A

Obtain reduced folate in diet
This is an example of selective toxicity for many drugs

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5
Q

Sulfonamides compete with this for folate synthesis pathway

A

PABA (p-aminobenzoic acid)

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6
Q

Sulfonamides are a ______ inhibitor of nucleic acid synthesis

A

Indirect

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7
Q

Sulfonamides are a _______ inhibitor dihyropteroate synthase which prevents PABA incorporation into folic acid

A

Competitive

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8
Q

Spectrum for sulfonamides

A

Broad spectrum
But resistance severely limits actual clinical spectrum

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9
Q

4 adverse effects of sulfonamides

A

Crystal formation in urine
Blood problems (esp. with G6P dehydrogenase deficiency)
Hypersensitivity
Kernicterus in infants

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10
Q

Glucose-6-P dehydrogenase deficiency is most commonly seen in people from this descent

A

Mediterranean and African origin

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11
Q

Highest risk of acute hemolysis as a result of sulfonamide use is in patients with this

A

Genetic deficiency in RBC glucose-6-phosphate dehydrogenase (FAVism)

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12
Q

Crystal formation in urine, blood problems, hypersensitivity, and kernicterus in infants are adverse effects of this

A

Sulfonamides

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13
Q

Rare medical emergency affecting skin and mucous membranes that can be triggered by sulfonamides
Fever, malaise, erythema multiforme, ulceration of mucous membranes

A

Stevens-Johnson syndrome

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14
Q

What is Stevens-Johnson syndrome?

A

Rare medical emergency affecting skin and mucous membranes that can be triggered by sulfonamides

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15
Q

2 Adverse effects of trimethoprim and pyrimethamine

A

Skin rashes
Major bone marrow toxicity potential when used chronically but can be reduced with folic acid supplementation (Megaloblastic anemia, Leukopenia, Granulocytopenia)

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16
Q

Skin rashes and bone marrow toxicity (megaloblastic anemia, leukopenia, granulocytopenia) are adverse effects to this

A

Trimethoprim and Pyrimethamine

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17
Q

Bone marrow toxicity when trimethoprim and pyrimethamine are used chronically can be reduced with this

A

Folic acid supplementation

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18
Q

Optimal ratio for Trimethoprim-Sulfamethoxazole combination therapy
Produce sequential blockage of folate synthesis; super additive drug interaction

A

20 parts Sulfa to 1 part Trimethoprim

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19
Q

Spectrum of quinolones

A

Broad spectrum (block DNA synthesis and function)
Effective for gram negative rods in UTIs and GI infections, and some gram positive

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20
Q

MOA of quinolones

A

Inhibit topoisomerase II (DNA gyrase) and IV

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21
Q

Quinolones inhibition of this is the primary drug target in gram negative bacteria

A

DNA gyrase (topoisomerase II)

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22
Q

Quinolones inhibition of this is the primary drug target in gram positive bacteria

A

Topoisomerase IV

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23
Q

Quinolones inhibition of DNA gyrase (topoisomerase II) is the primary drug target for this type of bacteria

A

Gram negative

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24
Q

Quinolones inhibition of topoisomerase IV is the primary drug target for this type of bacteria

A

Gram positive

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25
Q

Drugs that chelates with some metals (e.g. antacids containing aluminum hydroxide or magnesium hydroxide: Maalox, Mylanta)

A

Quinolones

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26
Q

Quinolones chelates with this

A

Some metals
(e.g. antacids containing aluminum hydroxide or magnesium hydroxide: Maalox, Mylanta)

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27
Q

4 Common problems with quinolone use

A

Nauseua, vomiting, diarrhea
Nephrotoxicity
Avoid use with antacids
3 C’s

28
Q

Quinolones should avoid use with these

A

Antacids

29
Q

Drug that should avoid use with antacids

A

Quinolones

30
Q

3 C’s of quinolones

A

Central nervous system (headaches, malaise, depression, psychosis, hallucinations)
Cartilage (ruptured tendons, avoid use in pregnancy and children)
Cardiac toxicity (QT prolongation)

31
Q

The 3 C’s (central, cartilage, cardiac) describe the adverse effects of this drug

A

quinolones

32
Q

Quinolones black box (3)

A

Avoid use in myasthenia gravis
Discontinue at first sign of tendon inflammation or pain
Tendon rupture

33
Q

Tendon most vulnerable to rupture with quinolone use
(all tendons are vulnerable)

A

Achilles tendon

34
Q

Tendon rupture can occur as early as _____ hours following first dose, and last ______ after last dose

A

Early as 48 hours
Last months after last dose

35
Q

Primary elimination of quinolones

A

Tubular secretion
Blocked by probenecid resulting in longer durations of serum antibacterial action

36
Q

Tubular secretion of quinolones is blocked by this, resulting in longer durations of serum antibacterial action

A

Probenecid

37
Q

Tubular secretion of this drug is blocked by probenecid, resulting in longer durations of serum antibacterial action

A

Quinolones

38
Q

2 antiseptic agents used to treat UTIs

A

Nitrofurans
Methenamine

39
Q

MOA of nitrofurans

A

Form reactive intermediates that damaged nucleic acid
Requires bacterial reduction enzymes (nitroreductases) for activation

40
Q

Nitrofurans require these for activation

A

Bacterial reduction enzymes (nitroreductases)

41
Q

This limits mammalian toxicity of nitrofurans (selectively toxic)

A

High biotransformation potential with rapid renal excretion keeps serum levels low

42
Q

Spectrum of nitrofurans

A

Mainly used as gram negative agent (narrow spectrum), but some important activity in gram positive (extended spectrum)

43
Q

This keeps serum levels of nitrofurans very low

A

First pass effect

44
Q

5 adverse effects of Nitrofurans

A

Nausea/vomiting
Hypersensitivity
Pulmonary reactions (acute pneumonia, interstitial fibrosis)
Peripheral neuropathy
Hemolytic anemia with RBC G6PD deficiency
Avoid use in late pregnancy

45
Q

2 pulmonary reactions with nitrofurans

A

Acute pneumonia
Interstitial fibrosis

46
Q

MOA of methenamine

A

Prodrug that is converted to formaldehyde in acid pH of 5.5 or less in urine, denaturing proteins and is toxic to most bacteria

47
Q

Methenamine is converted to this in acid pH of 5.5 or less in urine

A

Formaldehyde

48
Q

Spectrum of methenamine

A

Broad spectrum
Is converted to formaldehyde, which is toxic to most bacteria

49
Q

Bacteria that alkalize urine and disrupt methenamine mechanism

A

Proteus bacteria

50
Q

Proteus bacteria disrupt methenamine mechanism by doing this

A

Alkalize urine

51
Q

Methenamine is often combined with this to optimize activity

A

Urine acidifier mandelic acid

52
Q

2 contraindications of methenamine

A

Elevated ammonia levels make this contraindicated in hepatic dysfunction patients
Mandelic acid form contrainidicated in renal dysfunction patients to avoid acid crystallization

53
Q

Elevated ammonia levels (contraindicated in hepatic dysfunction patients) and mandelic acid form (contraindicated in renal dysfunction patients) are effects of this drug

A

Methenamine

54
Q

Urinary analgesic that alleviates symptoms of UTIs

A

Phenazopyridine (Azo)

55
Q

Phenazopyridine (Azo) is a minor metabolite of this

A

Acetaminophen

56
Q

This drug is a minor metabolite of acetaminophen

A

Phenazopyridine (Azo)

57
Q

Adverse effects of Phenazopyridine (Azo)

A

Body fluid discoloration
Not to be used in renal failure

58
Q

Drug that inhibits dihydropteroate synthase, preventing PABA incorporation into folic acid

A

Sulfonamides

59
Q

Blood problems (acute hemolysis in G6PD deficiency), hypersensitivity and Stevens-Johnson syndrome, and kernicterus in infants are adverse effects of this drug

A

Sulfonamides

60
Q

Drugs that inhibit dihydrofolate reductase

A

Trimethoprim and Pyrimethamine

61
Q

Skin rashes and bone marrow toxicity (megaloblastic anemia, leukopenia, granulocytopenia) are adverse effects of this

A

Trimethoprim and Pyrimethamine

62
Q

Drugs that inhibit topoisomerase II (DNA gyrase) and IV

A

Quinolones

63
Q

Part of quinolones black box indicates use should be avoided in this

A

Myasthenia gravis

64
Q

Tendon rupture is a characteristic adverse effect / warning of this drug

A

quinolones

65
Q

Drug that forms reactive intermediates and damaged nucleic acids

A

Nitrofurans

66
Q

Nausea/vomiting, hypersensitivity, pulmonary reactions (acute pneumonia, interstitial fibrosis), peripheral neuropathy, hemolytic anemia with RBC G6PD deficiency, and avoid use in late pregnancy are adverse effects of this

A

Nitrofurns

Pharmacology (14 decks)

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