Erythromycin

CLINICAL USE

Antibacterial agent

DOSE IN NORMAL RENAL FUNCTION

IV: 25–50 mg/kg/dayOral: 250–500 mg every 6 hours or 0.5–1 g every 12 hoursMaximum 4 g daily

PHARMACOKINETICS

Molecular weight :733.9

%Protein binding :70–95

%Excreted unchanged in urine : 2–15

Volume of distribution (L/kg) :0.6–1.2 (increased in CKD 5)

half-life – normal/ESRD (hrs) :1.5–2/4–7

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : 50–75 % of normal dose; maximum 2 g daily

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Not dialysed. Dose as in GFR <10 mL/min

HD :Not dialysed. Dose as in GFR <10 mL/min

HDF/high flux :Unknown dialysability. Dose as in GFR <10 mL/min

CAV/VVHD :Unknown dialysability. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsAvoid concomitant use with reboxetine and cilostazol

Anti-arrhythmics: increased risk of ventricular arrhythmias with parenteral erythromycin and amiodarone – avoid concomitant use; increased toxicity with disopyramide

Antibacterials: increased risk of ventricular arrhythmias with moxifloxacin and parenteral erythromycin avoid concomitant use; increased rifabutin concentration

Anticoagulants: enhanced effect of coumarins

Anti-epileptics: increased carbamazepine concentration and possibly valproateAntihistamines: possibly increases loratadine concentration; inhibits mizolastine metabolism – avoid concomitant use

Antimalarials: avoid concomitant administration with artemether/lumefantrineAntimuscarinics: avoid concomitant use with tolterodine

Antipsychotics: increased risk of ventricular arrhythmias with amisulpride and parenteral erythromycin avoid concomitant use; possibly increases clozapine concentration and possibly increased risk of convulsions; possibly increased risk of ventricular arrhythmias with pimozide and sertindole – avoid concomitant use; possibly increased quetiapine concentration

Antivirals: concentration of both drugs increased with amprenavir; concentration increased by ritonavirAnxiolytics and hypnotics: inhibits midazolam and zopiclone metabolism; increases buspirone concentration

Atomoxetine: increased risk of ventricular arrhythmias with parenteral erythromycin

Calcium-channel blockers: possibly inhibit metabolism of felodipine and verapamil; avoid concomitant use with lercanidipine

Ciclosporin: markedly elevated ciclosporin blood levels – decreased levels on withdrawing drug. Monitor blood levels of ciclosporin carefully and adjust dose promptly as necessaryColchicine: increased risk of colchicine toxicityCytotoxics: possible interaction with docetaxol; increases vinblastine toxicity – avoid concomitant use

Diuretics: increased eplerenone concentration –reduce eplerenone dose

Ergot alkaloids: increase risk of ergotism – avoid concomitant use5HT 1 agonists: increased eletriptan concentration – avoid concomitant useIvabradine: increased risk of ventricular arrhythmias – avoid concomitant use.278 eRYtHROMYCINLipid-lowering drugs: increased risk of myopathy; concentration of rosuvastatin reduced

Pentamidine: increased risk of ventricular arrhythmias with pentamidineSirolimus: concentration of both drugs increased

Tacrolimus: markedly elevated tacrolimus blood levels – decreased levels on withdrawing drug. Monitor blood levels of tacrolimus carefully and adjust dose promptly as necessaryTheophylline: inhibits theophylline metabolism; if erythromycin given orally decreased erythromycin concentration

ADMINISTRATION

Reconstition

1 g with 20 mL water for injection, then dilute resultant solution further to 1–5 mg/mL

Route

IV, oral

Rate of Administration

20–60 minutes using constant rate infusion pump

Comments

Use central line if concentration greater than 5 mg/mL; if >10 mg/mL monitor carefully (some units use 1 g in 100 mL of sodium chloride 0.9%). (UK Critical Care Group, Minimum Infusion Volumes for fluid restricted critically ill patients, 3rd Edition, 2006)

OTHER INFORMATION

May also give one third of daily dose by infusion over 8 hours peripherally at concentration of 1 g/250 mL (4 mg/mL). Repeat 8 hourly, i.e. continuouslyIncreased risk of ototoxicity in renal impairmentAvoid peaks produced by oral twice-daily dosing, i.e. dose 4 times dailyMonitor closely for thrombophlebitic reactions at site of infusion.

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