34.macrolides

Question 1

Macrolides definition

Answer 1

group of antibiotics with a macrocytic lactone structure to which one or more deoxy sugars are attached

Question 2

which macrolide is of first choice and as an alternative to penicillin

Answer 2

erythromycin

Question 3

classification of macrolides

Answer 3

1.erythromycin - drag.250mg
2.spiramycin - tab.250mg
3.clarithromycin -tab.250mg
4.azithromycin - caps.250mg and tab.500mg

Question 4

MoA of macrolides

Answer 4

1. bind irreversibly to 50S subunit of bacterial ribosome, inhibiting translocation steps
2. bacteriostatic
3. bacteriocidal at higher doses

Question 5

Resistance to macrolides is associated with:

Answer 5

1-inability of the organism to take up antibiotic
2-presence of efflux pumps
3-decreased affinity to 50S in gram +
4-presence of plasmid associated erythromycin esterases in gram - (enterobacteriaceae)

Question 6

administration of macrolides

Answer 6

1.oral
2.parenterally

Question 7

Erythromycin administration attention

Answer 7

base is destroyed by gastric acid

Question 8

which macrolides are stable in stomach acid and are readily absorbed

Answer 8

1.clarithromycin
2.azithromycin

Question 9

Food interference with absorption of Macrolides?

Answer 9

1.interferes with absorption of erythromycin and azitromycin
2.increases absorption of clarithromycin

Question 10

erythromycin and azithromycin are available in … formulations

Answer 10

IV

Question 11

distribution of macrolides

Answer 11

1.erithromycin distributes wll to all body fluids except CSF
2.clarithromycin, azithromycin are widely distributed in the tissues

Question 12

distribution of azitromycin

Answer 12

1. concentrates in neutrophils,
   macrophages and fibroblasts
2. has low serum levels
3. longest half life
4. largest volume of distribution

Question 13

metabolism of macrolides

Answer 13

hepatic

Question 14

excretion of macrolides

Answer 14

1.erythromycin and azithromycin are primarily concentrated and excreted in the bile as active drugs
2. partial reabsorption occurs through enterohepatic circulation

Question 15

erythromycin
1-oral absorption?
2-half life?
3-conversion to active metabolite?
4-percent excretion in urine?

Answer 15

1-yes
2-2
3-no
4-low

Question 16

clarithromycin

1-oral absorption?
2-half life?
3-conversion to active metabolite?
4-percent excretion in urine?

Answer 16

1-yes
2-3.5
3-yes
4-50

Question 17

azithromycin

1-oral absorption?
2-half life?
3-conversion to active metabolite?
4-percent excretion in urine?

Answer 17

1-yes
2-more than 40
3-yes
4-low

Question 18

adverse effects of macrolides

Answer 18

1-gastric distress
2-cholestatic jaundice
3-hepatotoxicity
4-metallic taste in mouth
5-allergic reaction

Question 19

drug interactions of macrolides

Answer 19

1-erythromycin and clarithromycin inhibit hepatic metabolism of many drugs, which leads to their toxic accumulation
2-with digoxin - increased absorption of it

Question 20

which macrolide has a broad SoA

Answer 20

azithromycin

Question 21

how are macrolides administered - before or after a meal?

Answer 21

after food

Question 22

clarithromycin metabolism?

Answer 22

1.to active metabolites in liver
2. is an enzyme inhibitor (of caffeine )

Question 23

excretion of azithromycin

Answer 23

via bile

Question 24

spiramycin excretion

Answer 24

via saliva

Question 25

indications for use of macrolides

Answer 25

1.skin infections
2.acne
3.RTI
4.H.pylori
5.STI
6.tonsillitis

Question 26

can macrolides be given in pregnancy?

Answer 26

yes after first half

Question 27

are macrolides bacteriostatic or bacteriocidal

Answer 27

bacteriostatic with a broad spectrum of

Question 28

drug interactions of macrolides

Answer 28

1. inhibit oxidation of drugs through interaction with cyt.P450 system
2. interfere with theophylline,statins