The literature stated that the dissolution rate of poorly soluble drugs improves when the drug is incorporated within polymeric carriers (60). This is due to a solid dispersion forming where the presence of hydrophilic polymers has several effects such as decreasing particle size of drug (61), which means the surface area is more extensive. The diffusion layer of each particle decreases in thickness which leads to a higher dissolution rate (52). Additionally, the dispersion of a drug within polymers is expected to increase drug wettability and also prevent drug aggregation, which will also lead to a faster dissolution rate (61). Increased drug wettability caused by water-soluble polymers is because of each drug crystal that is surrounded by soluble polymeric carriers which can readily dissolve and wet drug particle surface, which increases dissolution rate (62). Results obtained from in vitro dissolution studies (Fig. 5) confirmed this hypothesis as dissolution rate of ibuprofen sodium alone was slower, in comparison to dissolution rate when incorporated within the film. This was highlighted in drug release profile that at 15 min was 59%. When comparing this to F5 and F6 films, maximum drug release was 74% and 72% respectively. Dissolution profiles obtained also show a “spring and parachute,” where the pattern has a “spring” which is the initial dissolution of drug and then a “parachute” which refers to prolonged supersaturation of drug (63). Besides, F5 film had a faster dissolution rate due to smaller particles, which will increase surface area for dissolution (61).
Fig. 5 Dissolution profile of films and ibuprofen sodium a zoomed-in section of the first 60 min of dissolution and b full dissolution