Broad-Spectrum Penicillins Flashcards
What are common indications?
Amoxicillin-
Sinusitis, Otitis media, CAP
UTI, H.pylori
Co-amoxiclav-
(In severe, resistant,hospital acquired)
Pneumonia, UTI, intraabdominal infection, cellulitis and bone infections
What are examples?
Co-amoxiclav
Amoxicillin
What is the mechanism of action?
Broad spectrum of activity against:
Gram + and - cocci and bacilli (rods)
This is inactivated by bacterial penicillinases and resistance is more common
Why is amoxicillin often given with clauvulanic acid?
Clauvulanic acid is a beta lactamase inhibitor so restores activity against resistance
What is the mechanism of action of ALL penicillins?
Penicillins inhibit enzymes responsible for cross-linking peptidoglycans.
This weakens the bacterial cell wall, reducing its ability to maintain an osmotic gradient, causing cell swelling, lysis, and death.
How does the structure of broad spectrum penicillins differ from others
Has an additional amino acid group to the B lactam ring side chains increasing its activity against aerobic gram negative bacteria
What are common side effects?
C.difficile
Allergy: skin rash 7-10 days after first
1-2 days after repeat exposure
Acute liver injury such as jaunduice or hepatitis
May develop during or shortly after co-amoxiclav treatment
Who should be prescribed with caution/avoided?
Cautions:
Young people with sore throat ( can cause a rash with glandular fever which may be mislabelled as penicillin allergy)
C.diff
History of penicillin associated liver injury
Dose reduced in severe renal impairment
What are important interactions?
Methotrexate
Warfarin
What are common dosages for different indications?
Severe infection:
IV
Amoxicillin 1g 8 hourly
Co-amoxiclav 1.2g 8 hrly
Mild to moderate infection:
Oral
250-500mg TDS
Co-amoxiclav 625mg TDS
