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Respiratory Medicine Midterm > Sulfonamides, Antifolates, Fluoroquinolones - Fitzy lecture > Flashcards

Sulfonamides, Antifolates, Fluoroquinolones - Fitzy lecture Flashcards

1
Q

Sulfamethoxazole

Trimethoprim

A

Oral, IV
Renal clearance
T1/2 8-10 h

USE:

  • uncomplicated UTI, ear, sinus, respiratory infections, nocardiosis
  • s. typhus carrier eradication
  • toxoplasmosis, pneumocystis jiroveci
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2
Q

Adverse effects/toxicities Sulfamethoxazole -Trimethoprimin, Sulfadoxine -Pyrimethamine, Sulfadiazine - Pyrimethamine

A 
Rash
Steven-Johnson
Fever
leukopenia
acute hemolysis in G6PD deficiency
Hyperkalemia

higher incidence of adverse effects in AIDS patients (higher doses)

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3
Q

Sulfadoxine

Pyrimethamine

A

T1/2 4-8 days
Hepatic and renal clearance
Sulfa can displace albumin bound warfarin, bilirubin

USE:
malaria tx and prevention

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4
Q

Sulfadiazine - Pyrimethamine

A

Sulfa about 10 hrs
Pyrimethamine about 4 days

USE: toxoplasmosis

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5
Q

Sulfasalazine (Pro-drug)

A

Metabolism: colonic intestinal flora to sulfapyridine and 5-aminosalicylic acid (5-ASA)

5-ASA undergoes hepatic N-acetylation

USE:
ulcerative colitis, Crohns disease

Anti-inflammatory NOT abx

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6
Q

Sulfacetamide

A

topical eye drops, ointment

USE: ocular infections, trachoma

Adverse effects: hypersensitivity, Stevens-Johnson syndrome

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7
Q

Silver sulfadiazine

A

Topical cream

USE: dressing - prevent and treat 2nd and 3rd degree burn infection

Adverse effects: hypersensitivity, Stevens-Johnson syndrome

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8
Q

Sulfisoxazole/erythromycin

A

Powder for suspension - pediatric

USE: OM

Adverse events: superinfection - C. diff diarrhea, pseudomembranous colitis

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9
Q

Anthrax infection

A

suspected exposure

drug: ciprofloxacin

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10
Q

Pneumocystis jirovecii pneumonia

A

Indication: immunocompromised patient

Drug: trimethoprim-sulfamethoxazole

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11
Q

Toxoplasmosis infection

A

HIV infected with CD4 less than 100/uL

Drug: trimethoprim-sulfamethoxazole

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12
Q

MOA of sulfonamides

A

competitive inhibitors of dihydropteroate synthase (enzyme in folic acid biosynthesis of bacteria)

1- PABA substrate for bacterial folic acid synthesis
2- Sulfonamides resemble PABA
3- sulfonamides inhibit dihydropteroate synthesis

Gram + and - bacteria filling dihydrofolate pools by de novo biosynthesis of folic acid sensitive to sulfonamides
(Humans from diet, not affected)

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13
Q

Sulfamethoxazole -Trimethoprim (TMP-SMX) synergistic effect

A

Sulfamethoxazole inhibits dihydropteroate synthase

Trimethoprim inhibits dihydrofolate reductase

Individually bacteriostatic agents, combined bactericidal against many susceptible bacteria

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14
Q

Anti-microbial spectrum of TMP-SMX

A

Gram - rods:
E coli, Proteus mirabilis - cystitis, prostatitis

Salmonella typhi, Shigella spp. - diarrhea

H. influenzae - sinusitis

Other: Pneumocystis jiroveci (carinii) - pneumonia; Toxoplasmosis - encephalitis

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15
Q

Resistance mechanisms for TMP/SMX

A

Sulfamethoxazole (SMX): mutation of dihydropteroate synthase, enhanced acquisition of PABA

Trimethoprim (TMP): mutation of DHFR, over expression of DHFR

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16
Q

Pathogens resistant to TMP-SMX

A

P. aeruginosa
Bactericides fragilis (and most anaerobes)
M. tuberculosis - respiratory tract
T. pallidum - syphilis
Campylobacter - enteritis, diarrhea symptoms
PCN-resistant pneumococci - pneumonia
Rickettsiae

Folic acid auxotrophs naturally resistant (E. faecalis)

MRSA variable susceptible

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17
Q

Main therapeutic uses of SMX-TMP

A

Uncomplicated UTI
Prevention and tx of PCP in HIV patients
Toxoplasmosis in immunosuppressed

18
Q

Kernicterus in sulfonamide usage

A

Excess bilirubin in brain

neonatal encephalopathy due to sulfa drugs displacing bilirubin from albumin and poor bilirubin clearance

Developmentally inadequate glucuronidation in neonates

Contraindicated in near term and breast fed neonate due to liver immaturity

19
Q

Acute hemolytic anemia in sulfonamides

A

oxidative stress on erythrocytes
G6PD deficiency generate insufficient NADPH and excess GSSG and H2O2

Oxidants cause hemoglobin denaturation, acute hemolysis and RBC loss

20
Q

Adverse effects of trimethoprim

A

birth defects due to folate deficiency

21
Q

Fluoroquinolone properties

A

enter gram - via porins

bactericidal if concentration >30 fold MIC

concentration dependent killing

Gen 2, 3, 4 - effective against range of gram - rods, high bone penetration even with oral administration

active against atypical organisms causing pneumonia

22
Q

Fluoroquinolone MOA

A

inhibits DNA gyrase (topoisomerase II in gram - bacteria) and topoisomerase IV (more significant in gram + bacteria)

disruption of DNA lasting, post-antibiotic effect

23
Q

Mechanism of resistance in fluoroquinolone

A

Mutation of DNA gyrase and topoisomerase

cellular membrane efflux mechanisms

decreased number of porins - MDR

24
Q

2nd generation fluoroquinolone

A

Ciprofloxacin
Norfloxacin
Ofloxacin

25
Q

3rd generation fluoroquinolone

A

Levofloxacin

L-isomer of ofloxacin

26
Q

4th generation fluoroquinolone

A

Moxifloxacin

Gemifloxacin

27
Q

Ciprofloxacin organisms

A 
Atypical organisms:
Mycoplasma
Chlamydia
Mycobacteria
Legionella

Gram +:
Bacillus
anthraces - anthrax

Distinctive uses:
Anthrax
Osteomyelitis
Febrile neutropenia
Typhoid fever
Abdominal infections + Metronidazole
28
Q

Levofloxacin

A

Atypical organisms:
More active against mycoplasma
Chlamydia
Legionella

Gram + cocci - S. pneumonia

Distinctive uses:
Septic and pneumonic plague
Pyelonephritis

29
Q

Moxifloxacin

A

Atypical organisms:
Moer active against mycoplasma, chlamydia, legionella

Gram + cocci - enhanced gram + cocci and bacilli and anaerobes

No activity against p. aeruginosa

Distinctive uses:
Complicated intra-abdominal infections - anaerobic

30
Q

Treatment of CAP

A

Ciprofloxacin
Levofloxacin
Moxifloxacin
Gemifloxacin

31
Q

tx of Acute exacerbation of chronic bronchitis

A

Levofloxacin
Moxifloxacin
Gemifloxacin

32
Q

tx of Acute bacterial rhinosinusitis

A

Ciprofloxacin
Levofloxacin
Moxifloxacin

33
Q

tx of skin and skin structure infection

A

Ciprofloxacin
Levofloxacin
Moxifloxacin

34
Q

tx of Nosocomial pneumonia

A

Ciprofloxacin

Levofloxacin

35
Q

tx of bacterial prostatitis

A

Ciprofloxacin

Levofloxacin

36
Q

tx of UTI

A

Ciprofloxacin

Levofloxacin

37
Q

factors impacting absorption and bioavailability of fluoroquinolones

A

Antacids with Mg or aluminum

Dietary products with Calcium (milk, yogurt)

Vitamin mineral supplements with iron or zinc

Take separately, not together

38
Q

Fluoroquinolone elimination

A

Moxifloxacin - 20% urinary excretion and 60% hepatic

Ciprofloxacin - 50% urinary excretion, 20% hepatic

Levofloxacin - 85% urinary excretion, less than 5% hepatic

39
Q

Connective tissue problems associated with fluoroquinolone

A

Pediatrics: cartilage erosion, arthropy

Geriatric: tendon rupture, tendonitis (also athletes with tendon stress)

40
Q

Cardiac adverse effects of fluoroquinolones

A

Prolonged QTc interval via block of rapidly inactivating delayed rectifier Ik (hERG)
-blocks slow depolarization

Channel block and resultant QT prolongation dose-dependent and reversible

Moxifloxacin > gemifloxacin > levofloxacin

41
Q

Topically applied fluoroquinolones

A

administered to eye, ear drops
do not show adverse effects

Ciprofloxacin - eye and ear drops
Levofloxacin and Moxifloxacin - eye drops

42
Q

Peripheral neuropathy in Fluoroquinolones

A

oral or injection

no risk with topical formulations

Respiratory Medicine Midterm (11 decks)

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