Ex vivo permeation characteristics of venlafaxine through sheep nasal mucosa.

Venlafaxine, a dual acting antidepressant is a new therapeutic option for chronic depression. Depression is a common mental disorder associated with the abnormalities in neuronal transport in the brain. Since the nose-to-brain pathway has been indicated for delivering drugs to the brain, we analyzed the transport of venlafaxine through sheep nasal mucosa. Transmucosal permeation kinetics of venlafaxine were examined using sheep nasal mucosa mounted onto static vertical Franz diffusion cells. Nasal mucosa was treated with venlafaxine in situ gel (100 μl; 1% w/v) for 7h. Amount of venlafaxine diffused through mucosa was measured using validated RP-HPLC method. After the completion of the study histopathological investigation of mucosa was carried out. Ex vivo studies through sheep nasal mucosa showed sustained diffusion of venlafaxine with 66.5% permeation in 7h. Transnasal transport of venlafaxine followed a non-Fickian diffusion process. Permeability coefficient and steady state flux were found to be 21.11×10(-3) cmh(-1) and 21.118 μg cm(-2)h(-1) respectively. Cumulative amount permeated through mucosa at 7h was found to be 664.8 μg through an area of 3.14 cm(2). Total recovery of venlafaxine at the end of the permeation study was 87.3% of initial dose distributed (i) at the mucosal surface (208.4 μg; 20.8%) and (ii) through mucosa (664.8 μg; 66.5%). Histopathological examinations showed no significant adverse effects confirming that the barrier function of nasal mucosa remains unaffected even after treatment with venlafaxine in situ gel. Permeation through sheep nasal mucosa using in situ gel demonstrated a harmless nasal delivery of venlafaxine, providing new dimension to the treatment of chronic depression.