Development and in vitro-in vivo evaluation of fenretinide-loaded oral mucoadhesive patches for site-specific chemoprevention of oral cancer

Abstract

Purpose: To develop fenretinide oral mucoadhesive patch formulations and evaluate their in vitro and in vivo release performance for future site-specific chemoprevention of oral cancer.

Methods: Solubilization of fenretinide in simulated saliva (SS) was studied by incorporating nonionic surfactants (Tween® 20 and 80, and Brij® 35 and 98), bile salts (sodium salt of cholic, taurocholic, glycocholic, and deoxycholic acids), phospholipid (lecithin), and novel polymeric solubilizer (Souplus®). Adhesive (polycarbophil: hydroxypropyl methylcellulose 4KM) and drug release (Fenretinide/Eudragit® RL PO with or without solubilizers) layers were prepared by solvent casting. Oral mucoadhesive patches were formed by attaching drug and adhesive layers onto backing layer (Tegaderm™ film). Physical state of drug in Eudragit® films was examined by X-ray diffraction (XRD). Evaluation of in vitro and in vivo fenretinide release from the patch was conducted in SS containing 5%w/v sodium deoxycholate and rabbits, respectively. Fenretinide was quantified by HPLC.

Results: Tween® 20 and 80, Brij® 98, and sodium deoxycholate exhibited the highest fenretinide solubilization potential among the solubilizers. Drug loading efficiency in Eudragit® films was 90%-97%. XRD suggested fenretinide was amorphous in solubilizer-free and solubilizer-loaded films. Solubilizer-free patch exhibited poor in vitro and in vivo controlled drug release behavior. Increases in drug loading (5-10 wt%) or changes in polymeric matrix permeability did not provide continuous drug release. Co-incorporation of either single or mixed solubilizers in fenretinide/Eudragit® patches, (20 wt% Tween® 20, Tween® 80 and sodium deoxycholate or 20 wt% Tween® 80 + 40 wt% sodium deoxycholate solubilizers) led to significantly improved continuous in vitro/in vivo fenretinide release.

Conclusion: Fenretinide/Eudragit® RL PO patches with 20 wt% Tween® 80 + 40 wt% sodium deoxycholate solubilizers exhibit excellent release behavior for further preclinical and/or clinical evaluation in oral cancer chemoprevention.

Fig. 1

Schematic diagram (a), photographic image (b), and schematic cross-sectional diagram (c) of a mucoadhesive patch comprising drug (fenretinide/Eudragit® RL PO with or without solubilizers), adhesive (HPMC 4KM: polycarbophil (3:1), and backing (Tegaderm™ adhesive film) layers.

Fig. 2

Significant enhancement of fenretinide solubility in simulated saliva (pH 6.8) by non-ionic surfactants, bile salts, phospholipid, and novel amphiphilic polymer. Effect of co-incorporation of 0.5–5%w/v bile salts (a: sodium deoxycholate (●), sodium cholate (○), sodium glycocholate (△), and sodium taurocholate (◊)), nonionic surfactants (b: Brij® 35 (●), Brij® 98 (○), Tween® 20 (▲), and Tween® 80 (■)), novel polymeric solubilizer (c: Soluplus®), and phospholipid (d: lecithin) on the solubility of fenretinide in simulated saliva. Studies were conducted in amber color ampoules under evacuated conditions at 37°C and symbols represent mean ± SE, n = 3.

Fig. 3

Miscibility of fenretinide with Eudragit® RL PO. Effect of drug loading and co-incorporation of 20 wt% solubilizers on the miscibility of fenretinide with Eudragit® RL PO polymer. X-ray diffraction patterns of fenretinide (a), blank Eudragit® RL PO film (b), 5 (c) and 10 (d) wt% fenretinide, and 20 wt% Tween® 20 (e), sodium deoxycholate (f), Brij® 98 (g), and Tween® 80 (h) loaded Eudragit® RL PO films. Fenretinide loading in solubilizer-loaded Eudragit® RL PO films was 5 wt%.

Fig. 4

Co-incorporation of single or mixed solubilizers provides significantly improved continuous in vitro release of fenretinide from Eudragit® RL PO mucoadhesive patches. Effect of polymeric matrix permeability of Eudragit® (a: low permeability RS PO (○) and high permeability RL PO (●)), drug loading (b: 5 (●) and 10 (○) wt%), and co-incorporation of single (c: 0 (●) and 20 wt% Tween® 20 (▲), Tween® 80 (▽), Brij® 98 (◊), sodium deoxycholate (○)) or mixed (d: 0 (●), 40 wt% sodium deoxycholate (■), and 40 wt% sodium deoxycholate + 20 wt% Tween® 80 (○)) solubilizers on in vitro release of fenretinide. Fenretinide loading (theoretical) in a, c, and d formulations was 5 wt%. Eudragit® RL PO or RS PO mucoadhesive patch formulations with 5 and 10 wt% fenretinide, and 20 wt% sodium deoxycholate were prepared using triethyl citrate (20 wt%) as a plasticizer. Patch formulations loaded with 20 wt% surfactants (Tween® 20 and 80, and Brij® 98) were prepared without triethyl citrate. Studies were conducted in simulated saliva (pH 6.8) containing 5%w/v sodium deoxycholate under perfect sink condition (concentration of fenretinide was <10% of drug solubility in release medium) at 37°C and symbols represent mean ± SE, n = 3.

Fig. 5

Co-incorporation of single or mixed solubilizers significantly improved water uptake/polymer hydration characteristics of Eudragit® RL PO films. Effect of co-incorporation of single (a: 0 (▲) and 20 wt% Tween® 20 (●), Tween® 80 (□), Brij® 98 (△), sodium deoxycholate (○)) or mixed (b: 0 (▲), 40 wt% sodium deoxycholate (●), and 40 wt% sodium deoxycholate + 20 wt% Tween® 80 (■)) solubilizers on polymer hydration/swelling. Fenretinide loading (theoretical) in all the film formulations was 5 wt%. Films containing 20 wt% sodium deoxycholate were prepared using triethyl citrate (20 wt%) as a plasticizer. Films containing 20 wt% surfactants (Tween® 20 and 80, and Brij® 98) were prepared without triethyl citrate. Studies were conducted in simulated saliva (pH 6.8) containing 5%w/v sodium deoxycholate at 37°C and symbols represent mean ± SE, n = 3.

Fig. 6

Co-incorporation of solubilizers provides significantly improved continuous release of fenretinide from Eudragit® RL PO mucoadhesive patches after buccal administration in rabbits. a Effect of co-incorporation of mixed solubilizers (0 (△) and 20 wt% Tween® 80 + 40 wt% sodium deoxycholate (▲)) on in vivo release of fenretinide. b Comparison of in vitro (□) and in vivo (■) fenretinide release from solubilizers-free patches. c Comparison of in vitro (○) and in vivo (●) fenretinide release from 20 wt% Tween® 80 + 40 wt% sodium deoxycholate-loaded patches. In vitro release studies were conducted in simulated saliva (pH 6.8) containing 5% w/v sodium deoxycholate at 37°C. Fenretinide loading (theoretical) in all patch formulations was 5 wt%. Solubilizer-free patch formulation was prepared using triethyl citrate (20 wt%) as a plasticizer. Solubilizer-loaded patches were prepared without triethyl citrate. Symbols represent mean ± SE, n = 3 (in vitro) or 6 (in vivo).