Protein synthesis inhibitors

Question 1

Macrolides

Answer 1

Erythromycin

Question 2

newer macrolides

Answer 2

overcome limiatation of erythromycin
AZITHROMYCIN:
expanded spectrum, better tolerability.
Acid stable, rapid oral absorption
long T half

Question 3

Erythromycin

Answer 3

derived from streptomyces erythreus
alternatives to penicillin in people allergic to B lactams.
Mechanism:
bind irreversibly to site on 50S
preventing elongation of polypeptide chain.
bacteristatic

Question 4

Uses of macrolides

Answer 4

Respiratory tract infections
pertussis
skin and soft tissue infections
chlamydial infection.
H pylori infection

Question 5

Adverse effect of Macrolides

Answer 5

rashes, fever, eosinophilia, skin eruptions, severe epigastric pain
diarrhea in erythromycin

Question 6

Aminoglycosides

Answer 6

Natural or semisynthetic
Topical use - Neomycin, Framycetin
Systemic use - Streptomycin, gentamicin, amikacin.

Question 7

use of aminoglycosides and adverse effect

Answer 7

treating serious infections due to aerobic G-ve bacilli
bactericidal
bacterial endocarditis - gentamicin + vancomycin
tuberculosis - streptomycin
conjunctival infections
Framycetin ointment

adverse effects - nephrotoxic, ototoxic, NM blockade.

Question 8

mechanism of aminoglycosides

Answer 8

diffuse through porin channels
bind to 30S ribosomal unit
inhibiting protein synthesis

Question 9

What drugs used for the multidrug resistant like pseudomonas aeruginosa, klebsiella pneumoniae.

Answer 9

aminoglycosides + Blactams to employ synergistic

Question 10

Pharmacokinetics of aminoglycosides

Answer 10

highly polar
should be given parenterally except neomycin
rapid absorption from injection site in muscle.

Question 11

tetracyclines

Answer 11

Tetraycline, Chlortetracycline, oxytetracycline
broad spectrum
bacteriostatic

Question 12

mechanism of tetracyclines

Answer 12

enter cytoplasm
inhibit synthesis by binding to 30S
peptide chain fail to grow

Question 13

pharmacokinetics of tetracycline

Answer 13

absorbed from GIT
food retards absorption of tetracycline
widely distributed and get deposited in teeth, bone, tumors.
cross placental barrier
metabolized in liver and excreted in urine
Milk,curd, Ca+, Mg2+, Al3+ all impair absorption by chelation.

Question 14

Uses and adverse effect of tetracycline

Answer 14

cholera/ typhus fever/ pneumonia.
doxycycline have longer t half and lack nephrotoxicity so given to people with renal disease.
Amoebiasis/ PUD
Adverse effect:
nausea/ vomit/ epigastric burning/ staining of teeth/ hepatotoxicity during pregnancy/ renal toxicity (fanconi syndrome) is used after expiry date./ superinfections

Question 15

Chloramphenicol

Answer 15

Mechanism - bind to 50S
Induce bone marrow depression and aplasia
Uses - conjunctivitis/ external ear infections.
Gray baby syndrome - high level of free drugs accumulate to cause neonatal toxicity

Question 16

Lincosamide

Answer 16

Clindamycin
Protein synthesis inhibitor
Uses - anaerobic infections/ skin and soft tissue infections
combo with aminoglycosides or cephalosporin
Adverse effect -
pseudomembranours colitis/ P.colitis and clindamycin diarrhea/ skin rash/ liver dysfunction.

Question 17

Ketolides

Answer 17

Linezolid
50S inhibitor
Uses - gram positive only as effluxed by gram negative bacteria.
Treating multidrug resistant gram positive bacteria like
VRSA/ MRSA