Formulation Development of a Carrageenan Based Delivery System for Buccal Drug Delivery Using Ibuprofen as a Model Drug

Solvent cast films are used as oral strips with potential to adhere to the mucosal surface, hydrate and deliver drugs across the buccal membrane. The objective of this study was the formulation development of bioadhesive films with optimum drug loading for buccal delivery. Films prepared from κ-carrageenan, poloxamer and polyethylene glycol or glycerol, were loaded with ibuprofen as a model water insoluble drug. The films were characterized using texture analysis (TA), hot stage microscopy (HSM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), x-ray powder diffraction (XRPD), high performance liquid chromatography (HPLC) and in vitro drug dissolution. Optimized films were obtained from aqueous gels containing 2.5% w/w κ-carrageenan 911, 4% w/w poloxamer 407 and polyethylene glycol (PEG) 600 [5.5% w/w (non-drug loaded) and 6.5% w/w (drug loaded)]. A maximum of 0.8% w/w ibuprofen could be incorporated into the gels to obtain films with optimum characteristics. Texture analysis confirmed that optimum film flexibility was achieved from 5.5% w/w and 6.5% (w/w) of PEG 600 for blank films and ibuprofen loaded films respectively. TGA showed residual water content of the films as approximately 5%. DSC revealed a Tg for ibuprofen at −53.87 ̊C, a unified Tm for PEG 600/poloxamer mixture at 32.74 ̊C and the existence of ibuprofen in amorphous form, and confirmed by XRPD. Drug dissolution at a pH simulating that of saliva showed that amorphous ibuprofen was released from the films at a faster rate than the pure crystalline drug. The results show successful design of a carrageenan and poloxamer based drug delivery system with potential for buccal drug delivery and showed the conversion of crystalline ibuprofen to the amorphous form during film formation.