title: Metabolism of propionyl erythromycin lauryl sulfate. I. Fate of the propionyl erythromycin moiety in the rat.
abstract: The absorption, excretion, and metabolism of propionyl erythromycin (PE) has been studied in the rat. The major routes of metabolism of PE are ester hydrolysis and N-demethylation. The rates of these two reactions have been examined in vivo using radiolabeled PE. The plasma half-life of the ester is 5.5 hr. The correlation of blood levels of radioactivity with 14CO2 production indicates that the ester is continually hydrolyzed after absorption. The half-life of the dimethyl-amino moiety of the desosamine sugar is estimated at 1.5 hr. This relatively short half-life compared to that of the ester is supported by the fact that at 3.5 hr after dosing there is twice as much desmethyl-PE in plasma as PE. After oral administration of either 14C-PE or 14C-erythromycin, 70% of the radioactivity is absorbed in 6 hr. The major route of excretion is via bile. Approximatley 40% of the absorbed dose is excreted in bile in the first 6 hr after dosing. Tissue levels of radioactivity after administration of 14C-erythromycin or 14C-PE indicate that PE or a metabolite accumulates in the tissue during chronic dosing, whereas erythromycin-related levels are similar after single or multiple doses.
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002849:Chromatography, Gas; D003640:Dealkylation; D004917:Erythromycin / Q000031:analogs & derivatives*; D004918:Erythromycin Estolate / Q000097:blood / Q000378:metabolism*; D006207:Half-Life; D006868:Hydrolysis; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats
chemical_list: D002245:Carbon Dioxide; D004917:Erythromycin; D004918:Erythromycin Estolate