Penicillin broad spectrum

Question 1

What are the generic and brand examples of broad spectrum penicillins?

Answer 1

• Amoxicillin (Amoxil)

* Co-amoxiclav (Augmentin)

Question 2

What is the method of action of broad spectrum penicillins?

Answer 2

• B lactam rings inhibits the enzymes responsible for cross linking peptidoglycan in the bacteria cell walls
• = Weakened cell walls so cannot maintain an osmotic gradient
• Calvulanic acid is a B-lactamase inhibitor which increases the spectrum to include B-lactamase producing bacteria e.g. staphylococcus aureus

Question 3

What are the indications for broad spectrum penicillins

Answer 3

• Pneumonia which may be caused by gram positive (streptococcus pneumonia) or gram negative pathogens (haemophilus influenza)
• Urinary tract infection
• As part of combination treatment for hospital acquired infections/intra-abdominal sepsis caused by gram-negative and anaerobic pathogens
• Combination treatment for H. pylori associated peptic ulcers

Question 4

What are the contraindications of broad spectrum penicillins?

Answer 4

• At risk of C. Diff infections – use with caution
• History of penicillin allergy
• Severe renal impairment – risk of crystalluria

Question 5

What are the side effects of broad spectrum penicillins?

Answer 5

• GI upset – nausea, diarrhoea
• Antibiotic associated colitis = C.Diff
• Penicillin allergy – skin rash → anaphylactic reaction
• Cholestatic jaundice

Question 6

What drugs do broad spectrum penicillins interact with?

Answer 6

• Methotrexate – penicillin ↓ renal excretion = toxicity

* Warfarin – enhance anticoagulant effect by killing normal gut flora that synthesis Vit K

Question 7

Which organ eliminates broad spectrum penicillins?

Answer 7

Kidney