Quinolones

Question 1

Examples of fluroquinolones?

Answer 1

Ciprofloxacin
Levofloxacin
Moxifloxacin

Question 2

Mechanism of action of fluroquionolones?

Answer 2

Targets DNA gyrase in gram neg, topoisomerase IV in gram pos bacteria to inhibit DNA replication

Question 3

For fluroquinolones,
a) administration
b) absorption
c) distribution
d) clearance

Answer 3

a) oral, IV, opthalmic
b) well absorbed after oral ingestion; NO to calcium or divalent cations 2h before medication
c) high in bone, urine (sans moxi-), kidney, prostatic tissue
d) renal

Question 4

target organisms of fluroquinolones. types of infection.

Answer 4

C - gram neg, p. aeruginosa, e. coli, salmonella, shigella, campylobacter jejuni, bacillus anthracis, penicillin + cephalosporin + aminoglycoside resistant strains

travellers diarrhoae, food poisoning, skin, bone and joint infection, prostatis

L & M - same but + gram pos (s. pneumonia) + atypicals (m. pneumoniae, chlamydia pneumoniae, m. tb)

Question 5

What infections are not indicated for use by fluroquinolones

Answer 5

UTI, MRSA, Anaerobic Infections, Strep, Enterococci Infection

Question 6

adverse effects of fluoroquinolones

Answer 6

GI effects (nausea, vomiting, diarrhoae)
C. Diff Colitis (esp cip)
Headache, Dizziness, Light Headedness
Phototoxicity
Tendinitis or tendon rupture (NO to kids < 18)
Prolonged QT interval
Peripheral neuropathy

Question 7

drug interactions of fluroquinolones.

Answer 7

increase theophylline, warfarin, cyclosporine

Question 8

use of fluroquinolones in pregnancy

Answer 8

restrcited use. not use during breastfeeding

Question 9

shd pt with MG take fluroquinolones?

Answer 9

no

Question 10

3 types of anti-folate drugs.

Answer 10

1) sulfonamides
2) trimethoprim
3) co-trimoxazole

Question 11

mechanism of action of the 3 anti-folate drugs

Answer 11

1) blocks dihydropteroate synthase
2) blocks dihydrofolate reductase
3) blocks both

Question 12

for sulfonamides,
a) absorption
b) distribution
c) metabolism
d) excretion

Answer 12

a) oral, mostly well absorbed except sulfasalazine
b) bound to serum albumin; penetrate into CSF well even without inflammation
c) liver
d) renal, breast milk

Question 13

uses of sulfonamides

Answer 13

1. combined with co-trimoxazole for p. jirovecii
2. combined with pyrimethamine for drug-resistant malaria and toxoplasmosis
3. sulfasalazine in IBD
4. infected burns
5. respiratory infectioms
6. acute UTI

Question 14

adverse effects of sulfonamides.

Answer 14

1. crystalluria
2. hypersensitivity
3. hematopoietic disturbances
4. kernicterus (NO to newborns and infants < 2m and pregnant women at term

Question 15

drug interactions of sulfonamides.

Answer 15

potentiation of anticoagulant effect of warfarin (displacement from binding sites on serum albumin)

Question 16

clinical uses of trimethoprim. types of infection

Answer 16

enterobacter, e. coli, klebsiella pneumoniae/ UTIs and prostatitis (2nd line to fluroquinolones)

Question 17

for trimethoprim:
a) absorption
b) distribution
c) excretion

Answer 17

a) oral
b) widely distributed thruout body inc CSF; weak base so higher conc in acidic conditions
c) renal

Question 18

resistance of trimethoprim

Answer 18

altered dihydrofolate reductase
efflux pumps
decreased permeability

Question 19

adverse effects of trimethoprim

Answer 19

1. folic acid defiency sequelae
   - megaloblastic anemia
   - leukopenia
   - granulocytopenia

Question 20

how to reduce adverse effects of trimethoprim

Answer 20

effects can be reversed by simultaneous administration of folinic acid

Question 21

what is the combination for cotrimoxazole and in what ratio

Answer 21

trimethoprim and sulfamethoxazole (1:5)

Question 22

for cotrimoxazole,
a) administration
b) distribution
c) clearance

Answer 22

a) oral; IV (for severe pneumonia or UTI when pt unable to take drug orally)
b) distributes well thruout, esp in prostatic fluid
c) urine

Question 23

targets for co-trimoxazole:

Answer 23

1. E. Coli in UTIs
2. Hemophilus, Moraxella catarrhalis, Klebsiella pneumonia in Respiratory Tract Infections
3. Toxoplasmosis
4. MRSA and community-acquired skin and soft tissue infection
5. Pneumocystis pneumonia by P. jiroveci

Question 24

adverse effects of co-trimoxazole

Answer 24

1. rash
2. photosensitivity
3. GI effects (nausea + vomiting)
4. Glossitis and stomatitis
5. Hemolytic anemia in pt with G6PD deficiency (due to sulfamethoxzaole)
6. folic acid deficiency sequelae (megaloblastic anemia, leukopenia, thrombocytopenia)

Question 25

use of co-trimoxazole in pregnancy.

Answer 25

NO in 1st trimester (folic acid deficiency can cause dvt issues) and last trimester (worried for G6PD in children)

Question 26

drug interaction of co-trimoxazole

Answer 26

increase half life of phenytonin, enhance effect of warfarin

Question 27

Mechanism of action of nitrofurantoin?

Answer 27

bacteria will reduce drug to a highly active intermediate that inhibits various enzymes and disrupt synthesis of proteins, DNA, RNA and metabolic processes

Question 28

target organism of nitrofurantoin?

Answer 28

1. e. coli
2. enterococci

NO vs proteus, pseudomonas, enterobacter, klebsiella

Question 29

for nitrofurantoin,
a) administration
b) absorption
c) distribution
d) elimination

Answer 29

a) oral
b) rapid from GI tract
c) high urinary conc while limiting systemic exposure (due to rapid clearance) - good for UTIs
d) urine; acidic urine enhances drug activity

Question 30

adverse effects of nitrofurantoin?

Answer 30

1. GI effects (nausea, vomitting, diarrhea)
2. hypersensitivity
3. leukopenia, hemolytic anemia (a/w G6PD deficiency)
4. Cholestatic jaundice and hepatocellular damage (nitro-reductive metabolism produces injurious oxidative free radicals which damage hepatocytes) – note there may be prolonged incubation period to onset of liver injury, may lead to mistaken or delayed diagnosis
5. Pulmonary toxicity (elderly pt)
6. peripheral neuropathies (for pt with impaired renal functions or on long term treatment)