Abstract: Aim To investigate the relationship between pH environment of meptazinol hydrochloride (MEP) and its nasal absorption. Methods In situ nasal perfusion was performed to study the effect of pH environment on the nasal absorption. Its effect on the transport from nose to brain was further researched by in vivo experiment. Results In in situ perfusion experiment, the nasal absorption of MEP in basic environment was significantly higher than that in acid condition, but the difference was not observed in in vivo experiment. Conclusion The pH environment of meptazinol hydrocloride in formulation cannot be regarded as an important factor influencing nasal absorption and transport from nose to brain.

Key words: nasal absorption, nasal absorption, pH environment, pH environment, lipophilic drug, lipophilic drug, meptazinol hydrochloride, meptazinol hydrochloride