Application of hydrogel polymers for development of thyrotropin releasing hormone-loaded adhesive buccal patches

Abstract

To utilize hydrogels for fabricating thyrotropin releasing hormone (TRH) adhesive buccal patches, type of hydrogels such as polyacrylic acids (Polycarbophil AA1, Carbopols 934P, 974P and 971P), celluloses (HPMC K4M, K4MCR and K15M), polysaccharide (sodium alginate) and polyacrylic acid combinations with either cellulose or polysaccharide were evaluated for adhesion force, water uptake and swelling capacity. Upon the characterization of hydrogel polymers, TRH-loading of patches fabricated from these hydrogels was evaluated at various polymer concentrations, combinations and ratios and then in vitro release kinetics of TRH from these patches were studied. Results indicated that maximum adhesion force was shown by polyacrylic acids. Adhesive force of polymer combination mainly resulted from combination of adhesive force, according to ratio proportion used, of each polymer without any superimposed effect of polymer combination. Polycarbophil AA1 showed highest water uptake and swelling capacity. Maximum TRH-loading was obtained with sodium alginate and Polycarbophil AA1 and sodium alginate combination. TRH release profiles revealed that release was sustained from Polycarbophil AA1 and its combination with celluloses or polysaccharide at 2:1 level of polymer ratio. Based on adhesion, loading and release characteristics, patches of Polycarbophil AA1 with K4M, K4MCR and sodium alginate were concluded to be suitable for further development.

Patches as Polymeric Systems for Improved Delivery of Topical Corticosteroids: Advances and Future Perspectives

“…Soluble ALG also produces a viscous and cohesive 3D hydrogel structure that enhances mucoadhesive interactions [ 93 ]. High -viscosity polymers, such as ALG, have good mucoadhesive properties because, according to the diffusion theory of bioadhesion, both high viscosity and high MW ensure that the polymer chains penetrate the mucosa to a depth sufficient to create strong adhesive bonds by entanglement [ 94 ]. Moreover, due to their high porosity, ALG-based polymer patches also effectively load various drugs [ 95 ].…”

“…The bioadhesion of PAA arises mainly due to its hydrophilic nature, which promotes the wettability of the polymer and ensures strong adhesive contact with the mucosa [ 94 , 102 ]. The MW and cross-linking density of PAA affect its mobility and flexibility by reducing the effective length of the polymer chain that can penetrate and entangle within the mucosa and form adhesive bonds through this physical or mechanical interaction.…”

“…However, the mucoadhesive properties of polyacrylates can vary significantly, depending on the experimental conditions and type of mucin [ 103 , 104 , 105 ]; therefore, their specificity should be evaluated when designing patches with specifically desired functional characteristics [ 101 ]. Chinwala et al [ 94 ] developed oral patches for the delivery of thyrotropin-releasing hormone (TRH) based on different polymers, such as PAA, polycarbophil, Carbopol 934P, Carbopol 974P, and Carbopol 971P (MW of 700,000 to 3–4 billion), HPMC (MM of 1,200,000–1,800,000) and ALG, as well as various combinations of these polymers. The obtained patches had different mucoadhesive properties: the PAA- and HPMC-based patches exhibited maximum and minimum mucoadhesion, respectively; whereas ALG patches had adhesive characteristics intermediate between PAA and HPMC.…”