Antibacterial drugs

Question 1

Amoxicillin

Answer 1

CLASS: penicillin, B-lactam

MOA: peptidoglycan cross-linking –> cell wall

• Bactericidal
• Gram positive
• AE: allergy, SUPERINFECTION (most likely)

*Amoxicillin + clavulanate = inhibit action of beta-lactamases

*if allergic to penicillin, don’t use cephalosporins

Question 2

Cephalexin

Answer 2

CLASS: cephalosporin

MOA: peptidoglycan cross-linking –> cell wall

• Bactericidal
• Gram positive
• AE: nephrotoxicity

*if allergic to cephalosporins, don’t use penicillins

Question 3

Vancomycin

Answer 3

CLASS: glycopeptide

MOA: peptidoglycan synthesis –> cell wall

• Bactericidal
• AE: nephrotoxicity, ototoxicity, red man’s syndrome

*Require monitoring of drug levels due to nephrotoxicity and ototoxicity

Question 4

RIPE

Answer 4

*antimycrobacterials

RIFAMPICIN

MOA: inhibit RNA synthesis

• Bactericidal
• AE: drug interactions, red/orange secretions/hepatotoxicity

ISONIAZID (bactericidal), PYRAZINIMIDE (both), ETHAMBUTOL (bacteriostatic)

MOA: inhibits mycolic acid synthesis

• AE: hepatotoxicity (isoniazid)

Question 5

Sulphonamide

Answer 5

MOA: inhibits enzymes in folate synthesis

• Bacteriostatic

Question 6

Trimethoprim

Answer 6

MOA: inhibits dihydrofolate reductase (DHFR) activity

• Bacteriostatic

Question 7

Gentamicin, streptomycin

Answer 7

CLASS: aminoglycosides

MOA: 30S conformational change –> mRNA misread

• Bactericidal
• Gram negative
• Nephrotoxicity, ototoxicity

*Gentamicin requires monitoring of drug levels due to nephrotoxicity and ototoxicity

Question 8

Doxycycline

Answer 8

CLASS: tetracycline

MOA: 30S, inteferes with tRNA binding to mRNA+ribosome complex

• Bacteriostatic
• Gram positive + negative (broad)
• AE: black teeth, photosensitivity, impaired bone growth

*Contraindicated in newborns and late term pregnancies

Question 9

Erythromycin, clarithromycin

Answer 9

CLASS: macrolides

MOA: 50S, inhibits ribosome translocation

• Bacteriostatic (bactericidal at high doses)
• AE: cardiotoxicity

*Clarithromycin used against H. pylori

Question 10

Chloramphenicol

Answer 10

MOA: 50S, formation of peptide bonds

• Bacteriostatic (bactericidal at high doses)
• AE: grey baby syndrome

Question 11

Ciprofloxacin

Answer 11

CLASS: fluoroquinolones

MOA: inhibits DNA synthesis

• Bactericidal
• AE: tendon damage, rash

Question 12

Metronidazole

Answer 12

CLASS: NITROIMIDAZOLE

MOA: inhibits DNA synthesis, strand breakage

• Bactericial
• AE: metallic taste

*Used against anaerobes