EFFECTS OF DOSE, PH AND OSMOLARITY ON INTRANASAL ABSORPTION OF RECOMBINANT-HUMAN-ERYTHROPOIETIN IN RATS

The effects of dose, pH and osmolarity on the intranasal absorption of a recombinant human erythropoietin (rEPO) solution were studied in ma le Wistar rats, The intranasal administration of rEPO was evaluated by measuring percentage circulating reticulocytes of red blood cells on a stained blood smear (smear method), and also by measuring residual c irculating reticulocyte counts using a microcell counter (sysmex metho d), Both results suggest that rEPO solution was absorbed through the n asal mucosa of rats without enhancers after a single intranasal admini stration, The pharmacological availabilities of rEPO after intranasal administration compared with intravenous administration were about 7% and 4%, when estimated by smear method and sysmex method, respectively , The pharmacological activity was enhanced in low pH and hypotonic ma nnitol solution.