Anti-infectives (Beta-lactams - Penicillins)

Question 1

Examples of drug (Beta-lactams - Penicillins)

Answer 1

• Flucloxacillin
• Amoxicillin
• Benzylpenicillin
• Penicillin V

Question 2

Mechanism of action (Beta-lactams - Penicillins)

Answer 2

• Attaches to penicillin-binding-proteins on forming bacterial cell walls.
• This inhibits the transpeptidase enzyme which cross-links the bacterial cell wall.
• Failure to cross-link induces bacterial cell autolysis.
• Amoxicillin provides some amount of gram-negative cover in addition to gram-positive drugs

Question 3

Indications (Beta-lactams - Penicillins)

Answer 3

• Different penicillins have different indications for use because of a different spectrum of cover.
• Flucloxacillin provides Staphylococcus aureus cover whereas Amoxicillin does not.
• Flucloxacillin for soft tissue infection, Staphylococcal endocarditis and otitis externa.
• Amoxicillin for non-severe CAP

Question 4

Side effects (Beta-lactams - Penicillins)

Answer 4

• Diarrhoea
• Vomiting
• Liver function impairment
• Hypersensitivity reactions (severe reactions are rare; <0.05% are true hypersensitivity reactions)

Question 5

Important pharmacokinetics/pharmacodynamics (Beta-lactams - Penicillins)

Answer 5

• Good oral absorption.
• Flucloxacillin: Beta-lactamase stable/insensitive. This means Beta-lactamase producing bacteria are vulnerable to this drug.
• Amoxicillin: Beta-lactamase susceptible. This means Beta-lactamase producing bacteria are resistant to this drug. it is often combined with clavulinic acid, a beta-lactamase inhibitor.

Question 6

Patient information (Beta-lactams - Penicillins)

Answer 6

• Return if symptoms persists after the course of antibiotics, may be infected with resistant organism.
• Diarrhoea is a common side effect.
• Report any incidence of a rash after use – risk of hypersensitivity reactions.

Question 7

Other information (Beta-lactams - Penicillins)

Answer 7

• To overcome resistance in bacteria that secrete Beta-lactamase, a Beta-lactamase inhibitor is given with the penicillin.
• An example is Clavulonic Acid. When combined with amoxicillin, it forms co-amoxiclav.