The extended release properties of HPMC matrices in the presence of dietary sugars

Drug release from HPMC matrices in milk and fat‐rich emulsions

“…More fragile gel layers appear to be produced which show a greater sensitivity to erosion in in vitro dissolution tests. 12 Other studies have indicated that 40% (v/v) ethanol can accelerate the initial drug release from HPMC matrices through retarding polymer swelling. 14 Multivalent ions, such as phosphates, 15 citrates and organic species such as amino acids, can influence HPMC solubility, and this occurs in a Hofmeister rank order.…”

“…Different sugars have a rank order potency that correlates with their molecular ability to disrupt the structure of water, and by inference, the HPMC polymer hydration sheath. 12 Salts such as sodium chloride and sodium citrate (common food additives) can reduce the amount of sugar required to cause accelerated release to concentrations found in high-sugar soft drinks, and the effects of salts and sucrose appear to be additive. 13 The mechanism by which dietary sugars and sodium chloride elicit these effects appears, at least in part, to result from the suppression of HPMC particle swelling during initial matrix hydration, thereby inhibiting coherent gel layer formation.…”

“…12 The same formulation had been previously used in studies of the effects of dissolved sugars and salts. 12,29 Confocal laser scanning microscopy (CLSM) and magnetic resonance imaging (MRI) were used to explore the microscopic and macroscopic effects of interaction between fat emulsions and the rate-controlling surface "gel" layer of the hydrating matrix. Furthermore, two different USP dissolution test apparatus were used to explore the effects of hydrodynamics on matrix drug release behaviour.…”

The Properties of HPMC:PEO Extended Release Hydrophilic Matrices and their Response to Ionic Environments

“…This extreme concentration was chosen to disrupt HPMC particle coalescence and this is clearly seen in the extensive swollen mass of individual particles that have replaced the gel layer. This pattern signifies failure to establish a diffusion barrier that can block water penetration [10] and in the dissolution tests, these HPMC matrices released drug rapidly (Table 2). In contrast, the PEO matrix shows gel layer formation progressing normally, apparently unaffected by the high salt concentration and in the dissolution tests, these matrices retained their extended release properties (Table 2).…”

“…However, HPMC hydration can be influenced by ionic drugs, high concentrations of sugars, and inorganic salts according to their position in the Hofmeister lyotropic series [8]. The effects appear to be related to changes in water structuring and water-polymer binding but multivalent and high strength ionic solutions, can inhibit the formation of an effective surface barrier, and drug release is accelerated [9,10].…”