INFECTION: MACROCLIDES

Question 1

MACROCLIDES: INDICATIONS

Answer 1

• tx of resp and skin + soft tissue infections as an alternative to penicillin when it is CI
• Severe Pneumonia
• Eradication of H Pylori in combo with PPI inhibitor + (amoxicillin/metronidazole)

Question 2

MACROCLIDES: MOA

Answer 2

• Inhibit bacterial protein synthesis
• They bind to the 50S subunit of the bacterial ribosome and block translocation, a process required for elongation of the polypeptide chain.
• Inhibition of protein synthesis is ‘bacteriostatic’ (stops bacteria growth), which assists the immune system in killing and removing bacteria from the body

Question 3

MACROCLIDES: ADVERSE EFFECTS

Answer 3

• Most common and severe with ERYTHROMYCIN, but can occur with any MACROCLIDE
• Irritant causing nausea, vomiting, abdominal pain and diarrhoea when taken orally and thrombophlebitis when give IV
• Allergy, antibiotic associated colitis, liver abnormalities inc. cholestatic jaundice, prolongation of QT interval (predisposing to arrhythmias) and ototoxicity @ high doses

Question 4

MACROCLIDES: WARNINGS

Answer 4

• DO NOT prescribe with a Hx of Macroclide HS
• Mostly hepatic elimination, small renal component, prescribe with caution in those with severe renal impairment and dose reduction in severe renal impairment

Question 5

MACROCLIDES: INTERACTIONS

Answer 5

• Erythromycin and clarithromycin (but not azithromycin) inhibit cytochrome P450 enzymes. This increases plasma concentrations and risk of adverse effects with drugs metabolised by P450 enzymes
• EG Warfarin there is an icnreased risk of bleeding and with statins an increased risk of myopathy
• Prescribe with caution in patients taking other drugs that prolong the QT interval or cause arrhythmias such as AMIODARONE, ANTIPSYCHOTICS, QUININE, QUINOLONE ABs + SSRIs

Question 6

MACROCLIDES: EXAMPLES

Answer 6

• clarithromycin
• erythromycin
• azithromycin