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Quinolones, Folic Acid Antagonists and Urinary Antiseptics > Deck 1 > Flashcards

Deck 1 Flashcards

1
Q

Name 3 fluroquinolones

A

Ciprofloxacin
Levofloxacin
Moxifloxacin

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2
Q

Name 3 folic acid inhibitors

A

Sulfonamides
Trimethoprim
Cotrimoxazole

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3
Q

Name a Urinary Antiseptic

A

Nitrofurantoin

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4
Q

Name 2 Polymyxins

A

Polymyxin B

Colistin

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5
Q

Describe MOA of fluroquinolones

A

Target DNA gyrase, primarily in G(-) bacteria & topoisomerase IV in G(+) bacteria to inhibit DNA replication

  • DNA gyrase: Introduces negative supercoils into DNA to prevent excessive positive supercoiling
  • Topoisomerase IV: Promotes separation of chromosomal DNA into daughter cells (more common with G(+) bacteria e.g. Streptococci)
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6
Q

Describe MOA of sulfonamides

A
  • Competitive inhibitors of dihydropteroate synthase, the bacterial enzyme responsible for incorporation of para-aminobenzoic acid into dihydropteroic acid, the immediate precursor of folic acid
  • Sensitive microorganisms are those that must synthesize their own folic acid; bacteria that can use preformed folate are not affected
  • Bacteriostasis induced by sulfonamides is counteracted by PABA competitively
  • Mammalian cells require preformed folic acid, cannot synthesize it, are insensitive to drugs acting by this mechanism
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7
Q

Describe MOA of trimethoprim

A
  • Inhibits reduction of dihydrofolic acid by dihydrofolate reductase to its active form
  • Leads to decreased availability of tetrahydrofolate cofactors required for purine, pyrimidine, aa synthesis
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8
Q

Describe MOA of Cotrimoxazole

A
  • Synergistic antimicrobial activity of cotrimoxazole results from inhibition of two sequential steps in synthesis of tetrahydrofolic acid
  • Sulfamethoxazole inhibits incorporation of PABA into dihydrofolic acid precursors; Trimethoprim prevents reduction of dihydrofolate to tetrahydrofolate
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9
Q

Describe MOA of urinary antiseptics (Nitrofuratonin)

A
  • Sensitive bacteria reduce the drug to a highly active intermediate that inhibits various enzymes & disrupt the synthesis of proteins, DNA, RNA & metabolic processes
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10
Q

Describe MOA of Polymyxins

A
  • Bactericidal, cationic, surface-active agents that disrupt the structure of cell membrane phospholipids & increase cell permeability by a detergent like action
  • G(-) much more sensitive than G(+) because they contain more phospholipid in their cytoplasm & outer membranes
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11
Q

Describe MOA of Fosfomycin

A
  • Bactericidal
  • Interferes with cell wall synthesis in both G(+) & G(-) by inhibiting initial step involving phosphoenolpyruvate synthetase
  • Enters cells of Fosfomycin-susceptible bacteria by means of two different transport uptake systems & inhibits synthesis of peptidoglycan by blocking formation of N-acetylmuramic acid from N-acetylglucosamine and phosphoenolpyruvate
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12
Q

ROA of Fluroquinolones

A
  • Oral
  • IV
  • Ophthalmic
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13
Q

ROA of sulfonamides

A

Oral

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14
Q

ROA of trimethoprim

A

Oral

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15
Q

ROA of cotrimoxazole

A
  • Oral (common; full cup water)

- IV (severe pneumonia, UTI caused by susceptible organism where pt unable to take orally)

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16
Q

ROA of Nitrofurantonin

A

Oral

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17
Q

ROA of Polymyxin B

A

IV

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18
Q

Prodrug of Colistin

A

CMS (Colistimethate)

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19
Q

ROA of Colistin

A
  • Inhalation

- IV

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20
Q

ROA of Fosfomycin

A

Oral

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21
Q

List drug(s)/ drug class(es) best taken on empty stomach

A

Fluroquinolones

Fosfomycin

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22
Q

Fluroquinolones should not be taken with

A

with Ca or other divalent cations e.g. Al/Mg containing antacids, or dietary supplements containing Fe/Zn

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23
Q

Name the drug which has the following property: Not absorbed orally or suppository, thus reserved for tx of chronic inflammatory bowel disease (e.g. ulcerative colitis)

A

Sulfasalazine

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24
Q

Distribution of fluroquinolones

A
  • High levels in bone, urine (except moxi), kidney, prostatic tissue
  • Concentrations in lungs exceed serum
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25
Q

Distribution of sulfonamides

A
  • Bound to serum albumin
  • Distribute throughout bodily fluids & penetrate well into CSF fluid (even in absence of inflammation)
  • Pass placental barrier & enter fetal tissues
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26
Q

Name the drug(s)/ drug class(es) which penetrate well into CSF fluid

A

Folic acid inhibitors (sulfonamide, trimethoprim, cotrimoxazole)
Fosfomycin
Anti-Protozoal Agent (Metronidazole)

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27
Q

Name the drug class(es) & drug(s) which satisfy the following:
- Achieves very high urinary conc while limiting systemic exposure (due to rapid clearance), ideal targeted medication for UTI

A

Urinary antiseptics (Nitrofuratoin)

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28
Q

Distribution of trimethoprim

A
  • Weak base, so higher conc of trimethoprim achieved in relatively acidic prostatic & vaginal fluids
  • Widely distributed into body tissues & fluids, incl penetration into CSF
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29
Q

List the drugs which are excreted renally

A 
Fluroquinolones (cipro, levo, NOT moxi)
Folic Acid Inhibitors (all three)
Urinary antiseptics (Nitrofuratonin)
Polymyxins (ONLY CMS, NOT Colistin & Polymycin B)
Fosfomycin
Anti-Protozoal Agent (Metronidazole)
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30
Q

Name the drug(s) metabolized by liver

A

Moxifloxacin
Sulfonamides
Metronidazole

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31
Q

Drug(s) which causes crystalluria & potential damage to kidney

A

Sulfonamides

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32
Q

Describe MOA of Metronidazole

A
  • Amoebas possess electron transport proteins that participate in metabolic electron removal reactions
  • Metronidazole is a nitroimidazole
  • Nitro group of metronidazole is able to serve as an electron acceptor, forming cytotoxic free radicals that results in protein & DNA damage, and death of the E. histolytica trophozoites
  • Reduction in metronidazole requires strong reducing conditions & anaerobic organisms have more reducing potential than aerobic organisms
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33
Q

ROA of Metronidazole

A

Oral

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34
Q

Describe absorption of metronidazole

A

Completely & rapidly absorbed after oral administration

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35
Q

Drug(s) that crosses placenta

A

Sulfonamides

Fosfomycin

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36
Q

Drug(s) that are found in breast milk

A

Fosfomycin

Metronidazole

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37
Q

Drug(s)/ Drug Class(es) which require dose adjustment in renal failure

A

Fluroquinolones (cipro, levo)

Folic acid inhibitors (Sulfonamides, Trimethoprim)

38
Q

Drug which turns urine brown

A

Nitrofurantoin

39
Q

Name an inactive prodrug

A

CMS (Colistimethate)

40
Q

Describe the indications & spectrum of activity of ciprofloxacin

A

1) Active agst G(-) strains & enteric coliform incl penicillin, cephalosporin, aminoglycoside-resistant strains
2) Highly active agst P. aeruginosa
- Commonly used in cystic fibrosis pts for this indication
3) Skin, bone & joint infections
4) Traveler’s diarrhea caused by e. coli, food poisoning caused by all Enterobacteriaceae (E. Coli, Salmonella, Shigella), and Campylobacter jejuni
5) Typhoid fever caused by Salmonella typhi
6) UTI (not first line for simple UTI due to increasing resistance & adverse effects)
7) Used agst anthrax caused by Bacillus anthracis
8) Prostatitis

AVOIDED in MRSA due to resistance
INEFFECTIVE agst anaerobes
NOT VERY EFFECTIVE agst streptococci & enterococci

41
Q

Can ciprofloxacin be used against MRSA? Why?

A

Avoided in MRSA infections

  • Associated with high incidence of staphylococcal resistance
  • Ineffective against anaerobes
  • Not very effective against streptococci & enterococci
42
Q

Name 2 3rd generation furoquinolones

A

Levofloxacin

Moxifloxacin

43
Q

Which drug(s) are known as respiratory fluroquinolones?

A

Levofloxacin

Moxifloxacin

44
Q

Describe spectrum of activity of 3rd generation fluroquinolones as compared to ciprofloxacin

A
  • Better coverage agst G(+), esp S. pneumoniae
  • Increased coverage agst atypical pathogens e.g. Mycoplasma pneumoniae & chlamydia pneumoniae (vs cipro)
  • Useful agst respi infections due to a/m organisms & Mycobacterium tuberculosis
45
Q

What drugs can sulfonamides be combined with, what are they used for in their respective combinations?

A
  • Combi with trimethoprim (co-trimoxazole): for Pneumocystis carinii (now known as P. jirovecii)
  • Combi with pyrimethamine: for drug-resistant malaria & for toxoplasmosis
46
Q

Name an intermediate acting sulfonamide drug

A

Sulfamethoxazole

47
Q

Describe the indications of sulfonamides

A
  • Inflammatory bowel disease: sulfasalazine (sulfapyridine-aminosalicylate combination)
  • Infected burns: silver sulfadiazine; topically
  • Some STIs: e.g. trachoma, chalmydia, chancroid
  • Respi infections: use confined to a few special problems e.g. infection with Nocardia
  • Acute UTI: now seldom used
48
Q

What strains are now resistant to sulfonamides?

A

Many strains of formerly susceptible species incl meningococci, pneumococci, streptococci, staphylococci, gonococci are now resistant

49
Q

What drug has a similar spectrum of activity to sulfamethoxazole? List 3 species that are sensitive to both drugs.

A

Drug: Trimethoprim
Species: Enterobacter spp, E. coli, Klebsiella pneumoniae

50
Q

Describe the uses of Trimethoprim

A

May be used alone in tx of UTIs & in tx of bacterial prostatitis (although fluroquinolones are preferred)

51
Q

Is the spectrum of Cotrimoxazole broader, narrower, or the same as compared to sulfa drugs?

A

Broader

52
Q

What is Cotrimoxazole effective in treating? (5 points)

A

1) UTIs, E. coli
- Low dose can be given to women for recurrent UTI as prophylaxis or those with penicillin allergies
2) RTI caused by Haemophilus sp, Moraxella catarrhalis & Klebsiella pneumonia
3) Toxoplasmosis
4) MRSA & community-acquired skin & sort tissue infections caused by this organism
5) Pneumocystis pneumonia cause by Pneumocystis jiroveci
- (more common in immunocompromised patients, e.g. those with HIV/AIDS)
- (These pts also present with more adverse reactions e.g. fever, rashes, hyperkalemia, hyponatremia & diarrhea)

53
Q

Indication of Nitrofurantonin

A

Used in prevention & tx of lower UTIs (acute lower UTI, prophylaxis of lower UTI)

54
Q

Nitrofurantonin is effective against strains of (name 2)

A
  • E. coli

- Enterococci

55
Q

What species are resistant to nitrofurantonin?

A

most species of Proteus & Pseudomonas & many species of Enterobacter & Klebsiella

56
Q

Antibacterial activity of nitrofurantoin is ___ in acidic urine

A

higher

57
Q

Poymyxins have a ___ antibacterial spectrum, mainly Gram ___

A

Narrow; Negative

58
Q

Describe uses & spectrum of activity of polymyxins

A

Used for serious infections with multidrug-resistant G(-) bacteria

  • Especially those caused by Enterobacteriaceae family, including E. coli, Enterobacter spp, Klebsiella spp., Salmonella spp., Shingella spp.
  • Also have significant activity against Acinetobacter baumannii & P. aeruginosa
59
Q

What is polymyxins not active against?

A
  • Proteus spp. Legionella, Campylobacter, Vibrio cholera, G(-) cocci (Neisseria spp.), G(+) & anaerobic bacteria
60
Q

Describe uses of Inhaled CMS

A
  • Pseudomonas is a major cause of lung infections in people with cystic fibrosis (less so in Singapore)
  • Useful in respi infections & severe pneumonia due to MDR G(-) microbes
61
Q

Describe uses of Polymyxin B

A
  • Acute infections due to MDR G(-) microbes with no alternatives (E. coli, UTI, Klebsiella pneumoniae bacteremia)
  • UTI & bloodstream infections due to P. aeruginosa
62
Q

Fosfomycin has a ___ spectrum of activity against a ___ range of Gram ___ bacteria

A

broad; wide; positive & negative

63
Q

Name 2 Gram positive & 2 gram negative pathogens fosfomycin is active against

A

S. aureus & enterococcus

P. aeruginosa & Klebsiella pneumoniae

64
Q

Describe the uses of fosfomycin

A
  • Mainly in tx of UTIs, particularly caused by E. coli & Enterococcus faecalis
  • In combi with other abx in tx of nosocomial infections due to resistant G(+) & G(-) bacteria
  • Can have synergistic effects with beta lactam abx
  • Not suitable for pyelonephritis or severe urinary sepsis due to poor systemic absorption
65
Q

Describe the uses & spectrum of metronidazole (describe 4)

A

1) Amebic infections caused by Protozoa including:
- Entamoeba histolytica, Trichomonas vaginalis (vaginitis), Giardia lamblia (Giardiasis)
2) Anaerobes such as:
- Bacteroides species & Clostridium difficile
3) Helicobacter pylori (part of triple therapy for H. pylori infection)
4) Surgical prophylaxis (30-60 mins before incision)

66
Q

State & describe use of fluroquinolones in pregnancy

A

Cat C

  • Arthropathy observed in immature animals
  • Cipro detected in breast milk; Not recommended during breastfeeding
67
Q

State & describe use of sulfonamides in pregnancy

A

Avoid in pregnant women at term

68
Q

State the pregnancy classification of trimethoprim

A

Cat C

69
Q

State & describe use of cotrimoxazole in pregnancy

A

Use with caution

- Can cause folate deficiency

70
Q

State & describe use of nitrofurantoin in pregnancy

A 
Contraindicated:
(38-42 wks gestation)
- During labor or delivery
- When start of labor is imminent
- Reason: Possibility of hemolytic anemia
71
Q

State pregnancy category of fosfomycin

A

B

72
Q

State & describe pregnancy category of metronidazole

A

Cat B

  • But avoid use in first trimester
  • Only use if clearly needed (carcinogen in rodents)
73
Q

8 adverse events of fluroquinolones

A

1) N/V/D (most common)
2) C. diff colitis (especially cipro)
3) HA/dizziness/light HA
- Caution in pts with CNS disorders e.g. epilepsy
4) Phototoxicity
- Use sunscreen, avoid excess exposure to light
5) Tendinitis or tendon rupture
- Increased risk with systemic use
6) Joint problems (arthropathy)
- In young animals
- Not recommended in infants/children < 18yo
7) Prolong QTc interval (more common with 3rd gen)
- Should not be used in pts who are predisposed to arrhythmias or those who are taking other medications that cause QT prolongation
8) Peripheral Neuropathy
- With systemic use
- May occur any time during tx, may persist for months to years (even permanent) after drug stopped

74
Q

5 Adverse events of sulfonamides

A

1) Crystalluria
- Can result in development of nephrotoxicity
- Prevention by hydration & alkalization of urine; reduces concentration of drug & promotes its ionization
2) Hypersensitivity
- E.g. rashes, angioedema, SJS
- Previous sulfa allergies (note description)
3) Hematopoietic disturbances
- Hemolytic anemia encountered in patients with G6PD deficiency (lower ability to counter oxidative stress)
- Can also cause thrombocytopenia
4) Kernicterus
- May occur in newborns if taken by mums in late pregnancy
- Sulfa drugs displace bilirubin from binding sites on serum albumin
- Bilirubin is then free to pass into CNS, as BBB not fully developed
5) Drug potentiation
- Transient potentiation of anticoagulant effect of warfarin results from displacement from binding sites on serum albumin
- Reported in pts receiving both sulfamethoxazole & warfarin; increased monitoring recommended

75
Q

Name an adverse effect of trimethoprim & its effects

A

Effects of folic acid deficiency:

  • Megaloblastic anemia, leukopenia, granulocytopenia
  • Especially in pregnant pts & those having very poor diets
76
Q

In management of folic acid deficiency with trimethoprim, ___ administration of ___ is given

A

Simultaneous; folinic acid

77
Q

___ is a 5-formyl derivative of ___ which is readily converted to ___, which is then utilized for important cellular metabolic functions

A

Folinic acid; tetrahydrofolic acid; tetrahydrofolic acid

78
Q

List & describe 6 adverse events involving cotrimoxazole

A

1) Skin reactions e.g. rash (common)
2) Photosensitivity
3) GI effects e.g. N/V (most common)
4) Glossitis & stomatitis
5) Hemolytic anemia
- In pts with G6PD deficiency due to sulfamethoxazole component
6) Megaloblastic anemia, leukopenia, thrombocytopenia
- Can be fatal
- Hematologic effects reversed by concurrent administration of folinic acid, which protect pt & does not enter microorganism

79
Q

List & describe 7 common adverse effects of nitrofurantoin

A

1) N/V/D (common)
- Macrocrystalline preparation better tolerated
2) Hypersensitivity reactions (occasionally)
- Chills, fever
3) Leukopenia, hemolytic anemia (associated with G6PD deficiency)
4) Cholestatic jaundice & hepatocellular damage (rare)
- Nitro-reductive metabolism produces injurious oxidative free radicals which can damage hepatocytes
5) Pulmonary toxicity
- Elderly patients especially susceptible
6) Peripheral neuropathies (rare)
- Most likely to occur in pts with impaired renal function & persons on long-continued tx
7) Prolonged incubation period to onset of liver injury due to nitrofurantoin
- Frequently leads to mistaken or delayed dx

80
Q

List & describe 3 adverse events related to polymyxins

A

1) Nephrotoxicity (toxic to renal tubule cells)
- Avoid use with other nephrotoxic agents
2) Neurotoxicity (visual disturbances, vertigo, confusion, hallucinations, seizures)
- Usually associated with high serum levels in patients with renal impairment or nephrotoxicity
- DO NOT use in neuromuscular blockade agents & in pt with myasthenia gravis
3) Adverse events related to aerosolized CMS:
- Sore throat, cough, bronchoconstriction, chest tightness
- Bronchoconstriction can occur due to direct chemical stimulation, liberation of histamine, allergy in airway, irritation from chemicals
- Bronchoconstriction usually requires discontinuation of medication, administration of bronchodilators & supplemental oxygen

81
Q

List 3 adverse events of foscfomycin

A

1) GI disturbances (e.g. N/D)
2) HA
3) Vaginitis

82
Q

List 4 adverse events of metronidazole

A

1) GI
- N/V, epigastric distress, abdominal cramps
2) Unpleasant, metallic taste (common)
3) Oral moniliasis (yeast infection of mouth)
4) CNT & PNS Effects
- Convulsive seizures, optic & peripheral neuropathy
- Rare, but discontinue drug if happens
Avoid alcohol

83
Q

Contraindication of fluroquinolones

A

Avoid in pts with myasthenia gravis

- May exacerbate muscle weakness

84
Q

List 2 contraindication of sulfonamides

A
  • Newborns & infants < 2/12 age

- Pregnant women at term

85
Q

List 3 contraindications of urinary antiseptics

A

1) Impaired renal function (CrCl < 40 mL/min)
2) Pregnant women (38-42 wks gestation)
- During labor or delivery
- When start of labor is imminent
- Reason: Possibility of hemolytic anemia
3) Infants < 1 month of age
- Reason: Possibility of hemolytic anemia

86
Q

Quinolones may ___ serum levels of ___ & ___

A

raise; warfarin; cyclosporine

87
Q

Ciprofloxacin can ___ serum levels of ___ by ___

A

increase; theophylline; inhibiting its metabolism

88
Q

Cotrimoxazole can:

1) ___ half-life of ___
2) ___ effect of ___

A

increase; phenytoin;

enhance; warfarin

89
Q

metronidazole may ___ effects of ___

A

potentiate; warfarin

90
Q

Describe two mechanisms of resistance against trimethoprim

A

Resistance in G(-) bacteria due to:

  • Presence of altered dihydrofolate reductase that has lower affinity for trimethoprim
  • Efflux pumps & decreased permeability to the drug
91
Q

Describe resistance of bacterial against nitrofurantoin

A
  • Approved only for tx of UTI caused by microorganisms known to be susceptible to drug
  • Bacterial resistance to nitrofurantoin more frequent than resistance to fluroquinolones or trimethoprim-sulfamethoxazole
92
Q

Resistance to metronidazole ___(is/is not)___ a therapeutic problem for ___, although strains of ___ resistant to drug ___(have/have not)___ been reported

A

is not; amebiasis; trichomonads; have

Quinolones, Folic Acid Antagonists and Urinary Antiseptics (1 decks)

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