Macrolids

Question 1

What are examples of macrolids?

Answer 1

• Erythromycin

* Clarithromycin

Question 2

What is the method of action of macrolids?

Answer 2

• Binds to the 50S ribosomal sub-unit
• Inhibits protein synthesis
• Gram +ve bacteria
• Gram -ve bacteria
• Mycoplasma
• Penicillin resistant atypical organisms

Question 3

What are the indications for macrolids?

Answer 3

• URTI – tonsillitis, peritonsillar abscess, pharyngitis, laryngitis, sinusitis
• LRTI – bronchitis, pneumonia, Legionnaire’s disease
• Ear infections – otitis media/externa, mastoiditis
• Oral infections – gingivitis, Vincent’s angina
• Blepharitis
• GI: cholecystitis, H. pylori
• Prophylaxis for pre and post ops, burns, rheumatic fever

Question 4

What are the contraindications for macrolids?

Answer 4

• Macrolid hypersensitivity
• Severe renal impairment
• Severe hepatic impairment

Question 5

What are the side effects of macrolids?

Answer 5

• Nausea/vomiting
• Abdominal pain
• Diarrhoea
• Thrombophlebitis – IV
• Allergy
• Antibiotic associated colitis
• Cholestatic jaundice
• Prolonged QT interval → arrhythmias
• Ototoxicity – in ↑ doses

Question 6

What are the interactions with macrolids?

Answer 6

• Inhibits P450 enzyme
• Domperidone
• Pimozide/amisulpride (psychosis) – already prolongs QT interval
• Amiodarone – already prolongs QT interval
• Quinine – already prolongs QT interval
• Quinolone – already prolongs QT interval
• SSRIs – already prolongs QT interval
• Simvastatin - ↑ plasma concentrations = myopathy
• Colchicine
• Warfarin - ↑ risk of bleeding

Question 7

Which organs eliminate macrolids?

Answer 7

• Liver and kidney