Decrease in a constitutive form of cytochrome P-450 by macrolide antibiotics

The effects of administration of macrolide antibiotics on cytochrome P-450 in liver microsomes of male rats were investigated. The macrolides tested were those with a 14-membered ring such as oleandomycin, troleandomycin, erythromycin and erythromycin estolate, and those with a 16-membered ring such as rokitamycin, leucomycin and josamycin. The administration of the 14-membered ring macrolides may affect drug and steroid metabolism not only by formation of P-450-metabolite complex but also by decrease in the content of P-450-male