Effect of Promethazine Hydrochloride on Bone Resorption in Tissue Culture 1

Abstract

Abstract

The effect of promethazine hydrochloride, an established macrophage inhibitor, on bone resorption in tissue culture was examined. At nontoxic concentrations (5–25 μg/ml), promethazine hydrochloride inhibited, in a dose–response fashion, parathyroid extract-stimulated bone resorption and bone resorption in a bone remodeling system. Histological examination of sections prepared from cultured bones treated both with parathyroid extract and promethazine hydrochloride revealed an increase in number of macrophages in promethazine hydrochloride-treated cultures. At higher concentrations of this compound, but still within the same range of generally nontoxic concentrations (5–25 μg/ml), the macrophages appeared to be damaged. It is suggested that promethazine hydrochloride inhibits bone resorption in tissue culture by impairing macrophage function.