ABSTRACT
OBJECTIVE: To optimize the formulation of citalopram hydrobromide (CTH ) thermosensitive nasal gel and further evaluate its in vitro properties. METHODS: With gelling temperature and gelling time as evaluating indexes, central composite design-response surface and single factor experimental design method were used to optimize the formulation of CTH thermosensitive nasal gel by using poloxamer 407(F127) and carbomer 940 (CP940) as gel materials. Meanwhile, nasal mucosa permeation enhancer for CTH was then sieved by using Franz diffusion cell and ex vivo sheep nasal mucosa as experimental model. Finally, CTH thermosensitive nasal gel was prepared with cold method and then its in vitro properties was evaluated. In vitro cumulative erosion and cumulative release rate of the drug thermosensitive nasal gel were investigated by membrane-free dissolution method and dialysis membrane method, respectively. Moreover, the effect of temperature and pH on the viscosity of the drug nasal gel formulation was also evaluated. RESULTS: The optimal formulation of the thermosensitive nasal gel consisted of CTH 8.0%, F127 20.27%, CP940 0.17%, DM-β-CD 3.0%, ethylparaben 0.05% and distilled water. The gelling temperature, gelling time and pH of the drug thermosensitive nasal gel were found to be about 32.5 ℃,42 s and 5.0, respectively. The in vitro cumulative erosion and cumulative release percentage were both greater than 90% in 55 min and furthermore there was good linear correlation between these two parameters (r=0.998 6). Additionally, in vitro cumulative release of the drug from the gel formulation was determined to be 92% within 8 h, which conformed to Higuchi kinetic equation. Furthermore, the viscosity of the drug nasal gel was influenced by temperature as well as pH in different extent. CONCLUSION: The optimized formulation of the CTH thermosensitive nasal gel with central composite design-response surface method and single factor design method shows suitable gelling temperature, gelling time, pH value for nasal preparation and obvious in vitro drug sustained release characteristics.
ABSTRACT
OBJECTIVE: To investigate the pharmacokinetics of citalopram hydrobromide(CTH)thermosensitive nasal gel and further evaluate its brain delivery in rats. METHODS: The concentrations of CTH in rat plasma and brain tissue were determined by HPLC method. With intragastric administration (ig) of CTH solution as control, CTH thermosensitive nasal gel was intranasally given to rats and the concentrations of CTH in plasma and brain tissues were then determined. Moreover, the main pharmacokinetic parameters of CTH in plasma and brain tissues such as tmax, ρmax,relative bioavailability (Fr) and drug targeting efficiency (DTE) were estimated. RESULTS: Main pharmacokinetic parameters of CTH following nasal and ig administration to rats such as tmax and ρmax were 5 and 45 min, 2 152.86 and 589.68 ng•mL-1 in plasma, and 5 and 45 min, 17 660.56 and 1 171.68 ng•g-1 in brain tissue, respectively. Finally, the Fr and DTE of CTH thermosensitive nasal gel were found to be 184.91% and 250.03%, respectively. CONCLUSION: CTH thermosensitive nasal gel may be an ideal non-oral new dosage form with many advantages such as rapid in vivo absorption, high bioavailability and obvious brain delivery characteristics.