Block 4 Drugs

Question 1

Beta Lactams: Penicillins

Drugs

MoA

Uses

Answer 1

• Amoxicillin
  
  • Lower respiratory tract infections
• Flucloxacillin
  
  • Skin and soft tissue infections
  • Penicillinase resistant
• Co-amoxiclav
  
  • Mixed infections e.g. dental abscesses, complicated chest infections
• Benzylpenicillin
  
  • ​Tonsilitis

Bacteriocidal, target bacterial cell wall- block cell wall synthesis causing cell lysis.

Poor activity against intracellular organisms (e.g. legionella) or those with abnormal cell wall (e.g. chlamydia)

Side effects/interactions:

• Avoid use in patients with penicillin or cephalosporin induced anaphylaxis.
  *

Question 2

Beta-lactams: Cephalosporins

Drugs

MoA

Uses

Answer 2

• Ceftriaxone

Bacteriocidal: cause cell lysis by blocking cell wall synthesis

Uses:

• UTIs
• LRTIs
• Abdo sepsis
• Bacterial meningitis
• Orthopaedic infections

Side effects:

• Risk of CDAD (clostridium difficile associated diarrhoea)

Question 3

Beta-lactams: Carbapenems

Drugs

MoA

Uses

Answer 3

• Meropenem

Often used in multiresistant UTIs, complex infections and in intensive care.

Bacteriocidal- block cell wall synthesis causing cell lysis.

Question 4

Macrolides

Drugs

MoA

Uses

Answer 4

• Erythromycin

Bacteriostatic- target RNA and inhibit bacterial protein synthesis (less effective than bacteriocidal)

Uses:

• URTIs
• LRTIs
• SSTIs (in place of penicillins)
• atypical LRTIs (intracellular organisms)

Question 5

Tetracyclines

Drugs

MoA

Uses

Answer 5

• Doxycyline
• Tetracycline

Bacteriostatic- target RNA and inhibit bacterial protein synthesis

Uses:

• Atypical bacteria e.g. chlamydia, mycoplasma
• Rickettsia infections e.g. typhus

Side Effects:

• GI intolerance
• Photophobia

Question 6

Lincosamides

Drugs

MoA

Uses

Answer 6

• Clindamycin

Bacteriostatic- target RNA and inhibit bacterial protein synthesis

Given orally has excellent bioavailability

Uses:

• SSTI (instead of penicillins when limited IV access)
• Broad spectrum

Question 7

Quinolones

Drugs

MoA

Uses

Answer 7

• Ciprofloxacin

Bacteriostatic but bacteriocidal if high dose- target bacterial DNA structure and function to inhibit DNA coiling.

Uses:

• Gram -ve infections (excluding anaerobes)
• MRSA

Side effects:

• CDAD (clostridium difficile associated diarrhoea)

Question 8

Nitroimidazoles

Drugs

MoA

Uses

Answer 8

• Metronidazole

Bacteriostatic but bacteriocidal if high dose- inhibition of bacterial DNA synthesis.

Uses:

• Anaerobic infections (e.g. abscesses)