Erythromycin

Erythromycin - has an antibacterial spectrum similar but not identical to that of penicillin; it is thus an alternative in penicillin-allergic patients. Resistance rates in Gram ve organisms limit its use for severe soft tissue infections. Erythromycin has also been used as a prokinetic in gastric stasis and in aiding the passage of fine-bore feeding tube beyond the pylorus. Erythromycin is an agonist at motilin receptors. Motilin is a peptide secreted in the small intestine, which induces GI contractions, so increasing gut motility. Use as a prokinetic may increase patient colonisation with resistant bacterial species, including MRSA.

Uses
Alternative to penicillin (in patients with genuine penicillin allergy)
Community-acquired pneumonia, particularly caused by atypical organisms
Infective exacerbations of COPD
Legionnaires’ disease
Pharyngeal and sinus infections
As a prokinetic (unlicensed)

Administration
• IV infusion: 0.5–1.0 g 6 hourly
  Reconstitute with 20 ml WFI, shake well, then further dilute in
  250 ml sodium chloride 0.9% given over 1 hour
  CC >10 ml/min normal dose
  CC <10 ml/min 50–75% of dose, maximum 2 g daily in split doses
• As a prokinetic:125 mg 6 hourly PO/NG,125–250 mg 6–12 hourly IV.

How not to use erythromycin
IV bolus is not recommended
No other diluent (apart from WFI) should be used for the initial reconstitution
Do not use concurrently with simvastatin (myopathy) or sertindole
(ventricular arrhythmias)

Adverse effects
Gastrointestinal intolerance
Hypersensitivity reactions
Reversible hearing loss with large doses
Cholestatic jaundice if given >14 days
Prolongation of QT interval

Cautions
↑ Plasma levels of alfentanil, carbamazepine, ciclosporin, midazolam,
phenytoin, theophylline, valproate,warfarin and zopiclone.
Severe renal impairment (ototoxicity)
Hepatic disease

Organ failure
Renal: reduce dose

Renal replacement therapy
No further dose modification is required during renal replacement therapy