Preparation and Characterization of Hydroxypropyl Methylcellulose/Polyvinyl Alcohol Mucoadhesive Buccal Film of Cannabidiol

Cannabidiol is a non-psychoactive cannabinoid isolated from the cannabis plant. Instead of intoxicating effects, Cannabidiol is known for its antioxidant, anti-inflammatory, and anti-anxiety effects. Being antagonist to cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2) cannabinoid receptors, Cannabidiol binds to CB receptors through negative allosteric modulation; reduce binding affinity of endocannabinoids to corresponding receptors decreasing activities without adverse agonist effects. Cannabidiol could be administered via several routes, for example, oral, sublingual, nebulizing, and transdermal. However, due to its low water solubility and first-pass metabolism, Cannabidiol showed low bioavailability in several administrations, including the most common, oral delivery. Mucoadhesive drug delivery is one solution to increase drug retention time at oral absorption sites, buccal and sublingual, in which the drug could be absorbed directly into the bloodstream without passing through the digestive tract and its first-pass metabolism. Among several biocompatible mucoadhesive polymers, hydroxypropyl methylcellulose (HPMC) was found to be a suitable matrix that could be formulated into a thin film with up to 20% cannabidiol (CBD) content. To prolong the retention and disintegration time, polyvinyl alcohol (PVA) was added as a backing layer due to its softness and flexibility. The bilayer film showed excellent mechanical properties with tensile strength of 8.54 N/mm2 and elongation of 30%. The addition of a PVA backing layer not only improves mechanical properties but also prolongs up to 90 min of film disintegration time. HPMC-PVA film shows the controlled release of cannabidiol over a 4-hour period. The results indicate that HPMC-PVA bilayer is a suitable polymer matrix for cannabidiol delivery because it provides mucoadhesive properties in oral administration and controls release for higher cannabidiol absorption.