BIOLOGICAL ACTIVITY OF MEGALOMICIN, A NEW MICROMONOSPORA-PRODXJCED MACROLIDE ANTIBIOTIC COMPLEX

Abstract

In vitro studies with megalomicin A base demonstrated enhanced activity with increased pH, decreased activity with increasing serum content in the medium and serum binding in the range of 20-30%. There is an inoculum effect with megalomicin A. In vivo studies in mice demonstrate that megalomicins A, B, C₁, and C₂ as well as the complex are active in conventional protection tests and have low acute LD₅₀'s. Absorption of megalomicin A and C₁ in mice like erythromycin is better after parenteral than oral administration. In rats, and dogs, megalomicin A gives higher serum levels than erythromycin after oral dosing. Megalomicin A base is not emetic in dogs. Both megalomicins A and C₁ give more prolonged serum levels in dogs than does erythromycin. Megalomicin A is absorbed along the entire intestinal tract in dogs and gives a depot effect after intramuscular dosing.