Dose:    10 mg/kg/dose IV, PO
               Ophthalmic application

Frequency: Q 6 hours               

Comments: Erythromycin is active against gram positive bacteria, including some penicillin- resistant strains of staphylococci.   In addition B. pertussis, Chlamydia, ureaplasma and Mycoplasma are sensitive (most strains of Mycoplasma hominis are resistant. There is some risk of idiopathic hypertrophic pyloric stenosis when erythromycin is administered to newborns. Therapeutic levels are reached in all tissues and fluids except for the CNS and CSF.  The IV form erythromycin lactobionate must be given as a slow infusion because of its irritative effects on the vein.  Recommendations for the length of treatment are two to three weeks for pneumonia in the newborn due to Chlamydia and a minimum of 10 to 14 days for treating symptomatic infections (not involving the CSF) caused by U. urealyticum. Erythromycin is well absorbed from the GI tract, absorption is better with the estolate preparation which is also not effected by milk feedings.  A small double-blind study noted that oral erythromycin can improve feeding tolerance in low birth weight infants. The IV preparation contains benzyl alcohol.  For further comments on erythromycin.

Toxicity:    Bradycardia and hypotension have accompanied infusions of erythromycin lactobionate in VLBW infants.  This was probably related to the rapidity of the infusion. Concurrent use of theophylline in the newborn does not appear to be a major problem due to the immaturity of the cytochrome P-450 system. Cisapride is contraindicated while a patient is receiving erythromycin because concurrent use may cause ventricular tachycardia and ventricular fibrillation. Two reports have linked use of erythromycin in newborns with the development of idiopathic hypertrophic pyloric stenosis. The other major effect seen with erythromycin is loose stools since it is an effective prokinetic agent.  Adverse reactions to erythromycin.

Preparation:
IV: Erythromycin lactobionate (Erythrocin) is available in a 500 mg vial.  Add 10 ml sterile water for injection (PF) to the 500 mg vial for a 50 mg/ml concentration. This vial is stable for 2 weeks if refrigerated, or 24 hours at room temperature. To dilute in D5W, withdraw 2.4 ml of the 50 mg/ml erythromycin lactobionate and add 27.6 ml of D5W (total volume 30 ml). Dispensed in plastic bag with a concentration of 4 mg/ml. This procedure can also be used with normal saline as a diluent. To prepare using LR, withdraw 8 cc of erythromycin lactobionate (50 mg/ml) and add to 92 ml of lactated ringers. Final concentration for infusion is also 4 mg/ml. All of the reconstituted solutions must be used within 24 hours of preparation.  Infuse over 1 hour (infusion policy). Contains benzyl alcohol.

The stability of erythromycin lactobionate is extremely pH dependent. It is most stable at pH 6 to 8. Decomposition occurs at an increasingly rapid rate as pH approaches 4. A pH < 5.5 and > 10, there is a 10% decomposition of the drug within 6 hours.

PO: For the ethylsuccinate suspension (EES), 200 mg/5 cc, add required amount of distilled water to the bottle in two divided portions. Shake well after each addition and prior to administration. Refrigerate. Reconstituted solution stable for 14 days. The estolate suspension (Ilosone) is available as 125 mg/5 ml or 250 mg/5 ml suspensions.

Compatibility: Compatible with filter and TPN (up to D20 and 3% AA).  Compatible with NS, LR, and D5W. It is also probably compatible with D5NS and D5LR, the compatibility of the drug in dextrose-containing solutions is dependent upon the pH of the solution and may require the addition of a sodium bicarbonate additive. Care should be taken if infusing into a dextrose-containing solution not mentioned in the preceding. Compatible with acyclovir, aminophylline, enalaprilat, esmolol, famotidine, heparin (as long as concentration < 50 units/ml), hydrocortisone, labetalol, lidocaine, lorazepam, magnesium sulfate, methicillin, midazolam, morphine, penicillin G potassium, penicillin G sodium, phenobarbital, potassium chloride, ranitidine, sodium bicarbonate, and zidovudine.  Incompatible with cephalothin, fluconazole, furosemide, and metoclopramide.  Ampicillin has equivocal solubility with erythromycin.