Amorphous phases generated by pharmaceutical processes lead to cocrystal formation under conditions where there is increased molecular mobility and complementarity. Water, a potent plasticizer, enhances the rate of cocrystallization. This has powerful implications to control process induced transformations.

No abstract

No abstract

A new commercially available sustained-release matrix material, Kollidon SR, composed of polyvinylacetate and povidone, was evaluated with respect to its ability to modulate the in vitro release of a highly water-soluble model compound, diphenhydramine HCl. Kollidon SR was found to provide a sustained-release effect for the model compound, with certain formulation and processing variables playing an important role in controlling its release kinetics. Formulation variables affecting the release include the level of the polymeric material in the matrix, excipient level, as well as the nature of the excipients (water soluble vs. water insoluble). Increasing the ratio of a water-insoluble excipient, Emcompress, to Kollidon SR enhanced drug release. The incorporation of a water-soluble excipient, lactose, accelerated its release rate in a more pronounced manner. Stability studies conducted at 40 degrees C/75% RH revealed a slow-down in dissolution rate for the drug-Kollidon SR formulation, as a result of polyvinylacetate relaxation. Further studies demonstrated that a post-compression curing step effectively stabilized the release pattern of formulations containing > or = 47% Kollidon SR. The release mechanism of Kollidon-drug and drug-Kollidon-Emcompress formulations appears to be diffusion controlled, while that of the drug-Kollidon-lactose formulation appears to be controlled predominantly by diffusion along with erosion.

A newly available polyvinylacetate aqueous dispersion, Kollicoat SR 30D, was evaluated with respect to its ability to modulate the in vitro release of a highly water-soluble model compound (diphenhydramine hydrochloride) from nonpareil-based systems. Kollicoat SR 30D premixed with a selected plasticizer (10% wt/wt propylene glycol, 2.5% triethyl citrate, or 2.5% dibutyl sebacate), talc, and red #30 lake dye was coated onto the drug beads in an Aeromatic Strea I fluid-bed drier with a Wurster insert using bottom spray. With propylene glycol as the plasticizer, increases in polymer coating level retarded drug release from beads in a stepwise fashion along with apparent permeability, indicating a consistent release mechanism. Stability studies at 40°C/75% RH revealed gradual decreases in dissolution rate, and additional curing studies further confirmed the dependence of release kinetics on curing condition. Furthermore, the type of plasticizer was found to play a key role. Unplasticized formulations exhibited the fastest dissolution, followed by formulations plasticized with triethyl citrate, propylene glycol, and dibutyl sebacate. All 4 formulations (unplasticized and plasticized), nevertheless, revealed a marked difference between uncured and cured dissolution profiles. Kollicoat SR 30D has, thereby, been demonstrated to effectively retard drug release from nonpareilbased systems. However, selected plasticizer type and subsequent curing condition play important roles in controlling drug release from such a system.