Macrolides

Question 1

Describe the structure of Macrolides

Answer 1

They consist of a microcyclic lactone ring consisting about 14 to 16 carbons attached to it are deoxy sugars

The prototype erythromycin consists of the macrocyclic lactone ring containing 14 c and attached to it are 2 deoxy sugars

Question 2

The mechanism of action of Macrolides are

Answer 2

Inhibition of translocation
Inhibition of transpeptidation
Inhibit formation of 50s ribosome

Question 3

What advantage does Macrolides have compared to penicillin G

Answer 3

Alternative in patients with penicillin allergy

Question 4

Coating of erythromycin are ……

Answer 4

Stearate
Ethylsuccinate

Question 5

Erythromycin distributes well into body fluids except…….

Answer 5

CSF and brain

Question 6

Erythromycin is capable of crossing the placenta and reaching the fetus

Question 7

All Macrolides concentrate in …..

Answer 7

Liver

Question 8

Theresa no nephrotoxicity in macrolides T/F

Answer 8

True

Question 9

What are the clinical uses of erythromycin

Answer 9

Corynevacterial infections

Respiratory, genital, and neonatal chlamydia infections

Used in the treatment of community-acquired pneumonia because it has activities against pneumococcus, mycoplasma pneumonia, L.pnemophilia

Substitute for penicillin in penicillin allergic individuals who have strept and staph infections

Prophylaxis for infective endocarditis in dental procedures in patient with valvular heart disease

Question 10

Why is erythromycin not preffered as the first line agent in pharyngitis and skin and soft tissue infections

Answer 10

Erythromycin Resistance in staphylococci and group A streptococci

Question 11

Resistant strept and staphylococci are also resistant to ………

Answer 11

Clarithromycin

Question 14

Clindamycin has replaced Amoxicillin in ………

Answer 14

Prophylaxis of infective endocarditis

Question 15

What adverse effect of erythromycin warrants selecting an alternative?

Answer 15

Increased gastric motility

Question 16

Why is erythromycin used in patients with gastroparesis?

Answer 16

Due to it’s increased mobility effect

Question 17

List the side effects of macrolides?

Answer 17

Git motility and distress

Allergic reactions :Cholestatic jaundice or hepatitis
Eosinophilia and rashes

Fever

Ototoxicity

QTc prolongation

Question 19

What’s the contraindication for Macrolides

Answer 19

Patient with hepatic dysfunction

Question 20

Clarithromycin is different from erythromycin by

Answer 20

Methyl group

Moteacid stable and orally absorbed

Question 22

Clarithromycin is similar to erythromycin in respto the spectrum of activity but differs in ………

Answer 22

They are more active against intracellular pathogens such as

Chlamydia, legionella, moraxella, urea plasma sp and H pylori

Question 24

Erythromycin increases the serum concentration of ……… drugs by inhibiting the cyp450

Answer 24

Theophylline
Warfarin
Methylprednisolone
Cyclosporine

Question 25

Erythromycin increases the serum conc of ......... by increasing its ............

Answer 25

Oral.digoxin Bioavailability

Question 26

Clarithromycin has activities against..........

Answer 26

Toxoplasmosis gondii, H influenza and MAC mycobacteria avium complex

Question 28

Characteristics pf fodamixin

Answer 28

Very poor oral absorption, minimally absorbed stays in the GI hence suitable for treatment of clostridium difficile Macrocyclic antibiotics with similar structure to macrolides Unique target: RNA polymerase thus preventing transcription and terminate protein synthesis Narrow spectrum limited to gram +ve aerobes and anaerobes

Question 29

Why was telithromycin revoked?

Answer 29

Because it can cause hepatitis and liver failure and worsen muscle weakness in myasthenia gravis Life-threatening breathing problems

Question 30

Why are gram -ve aerobes resistant to climdamycin

Answer 30

Intrinsic resistance due to poor permeability of the outer membrane

Question 32

What's the major difference in the spectrum of activity of Macrolides?

Answer 32

Clarithromycin is more active against intracellular pathogens( others) such as chlamydia, legionella, moraxella, H.pylori, ureaplasma

Question 33

Erythromycin resistant strept and staph are also resistant to ......

Answer 33

Clarithromycin

Question 34

Clarithromycin has activity against......

Answer 34

Toxoplasmosis gondii MAC Mycobacterium leprae H.influenza

Question 35

Clarithromycin is, metabolised into a active metabolite .............

Answer 35

14-hydrpxyclarithromycin amd also has antibacterial activity

Question 36

The major advantage arithromycin has over erythromycin is ......

Answer 36

Lower incidence of GI intolerance Less frequent dosing

Question 37

Both erythromycin and Clarithromycin inhibiti cyp.....

Answer 37

Cyp3A4 and drug transporter P-glycoprotein

Question 38

Azithromycin is similar to erythromycin but different by.......

Answer 38

15C lactone ring and addition of methylated nitrogen into the lactone ring

Question 39

What advantages does azithromycin have over the others?

Answer 39

Less active against strept and staph and slightly more active against respiratory pathogens such as H. Influenza and moraxella catarrhalis Highly active against chlamydia sp.

Question 40

................ has the largest volume of distribution of the macrolides.?

Answer 40

Azithromycin with conc 10-100 folds greater than in the plasma

Question 41

Which of the Macrolides is best suited for once daily dosing and shortening of the duration of the treatment

Answer 41

Azithromycin because of its slow release from tissues