Cephalosporins

Question 1

What are examples of cephalosporins

Answer 1

• Cephradine
• Cefalexine
• Cefotaxime

Question 2

What is the method of action of cephalosporins?

Answer 2

• Contains β-lactam ring
• Inhibit the enzyme responsible for cross linking peptidoglycans in bacteria cell walls
• Weakens cell wall = cannot maintain osmotic gradient
• → cell swelling, lysis and death
• Activity against gram -ve bacteria (↑ as generation ↑)
• Naturally more resistant to β-lactamases than penicillins due to dihydrothiazine ring

Question 3

What are the indications for cephalosporins?

Answer 3

• 2nd and 3rd line treatment options for urinary and respiratory tract infections
• IV – severe/complicated/caused by antibiotic resistance organisms due to their broad spectrum

Question 4

What are the contraindications for cephalosporins?

Answer 4

• Risk of C.Diff infections – be cautious e.g. elderly
• History of allergy
• Renal impairment – dose ↓ required

Question 5

What are the side effects of cephalosporins?

Answer 5

• GI upset – diarrhoea and vomiting
• Antibiotic associated colitis (C.Diff)
• Hypersensitivity
• CNS toxicity – inc. seizures

Question 6

What are the interactions with cephalosporins?

Answer 6

• Warfarin - ↑ anticoagulant effect by killing normal gut flora that synthesises Vit K
• Aminoglycosides - ↑ nephrotoxicity

Question 7

Which organ eliminates cephalosporins?

Answer 7

Kidney