Amoxicillin

Question 1

Drug class?

Answer 1

Penicillins - Beta-lactam, broad spectrum penicillin.

Question 2

How does it work?

Answer 2

Bactericidal - interfere with cell wall synthesis.

Question 3

Indications?

Answer 3

• Gram +ve bacterial infections (e.g. streptococcus spp, staphylococcus spp) - Gram –ve bacterial infections (e.g. haemophilius influenzae)
• Spectrum: haemolytic streptococci, enterococcus faecalis, streptococcus pneumoniae, listeria monocytogenes, clostridium perfringens. Has some gram -ve activity but some strains produce a beta lactamase which degrades it.
• Indications: UTIs, otitis media, sinusitis, bronchitis, CAP, invasive salmonellosis, listerial meningitis. Can be used for anthrax and endocarditis. Crosses the BBB.

Question 4

Contra-indications?

Answer 4

Penicillin hypersensitivity. Caution - amoxicillin should be used with caution if suspected glandular fever (EBV, CMV) or known acute/chronic lymphocytic lukaemia, as there is a risk of an erythamatous rash developing.

Question 5

Side-effects?

Answer 5

Nausea, vomitting, diarrhoea, rashes.

Question 6

Possible interactions?

Answer 6

OCP - decreased effectiveness.
Digoxin - Digoxin toxicity.
Methotrexate - methotrexate toxicity.
Anticoagulants - prolonged bleeding time.