Erythromycin bioactivity is stable in ophthalmic ointment used for prophylaxis of neonatal gonococcal conjunctivitis

Erythromycin ophthalmic ointment (E. Fougera & Co., Melville, N.Y.) and erythromycin gluceptate standards prepared in ointment base were stored at room temperature and heated at temperatures up to 45 degrees C for as long as 6 h before being assayed for bioactivity. We were unable to detect any significant loss of antibiotic bioactivity.