The incorporation of low-substituted hydroxypropyl cellulose into solid dispersion systems

Downstream processing of spray-dried ASD with hypromellose acetate succinate - Roller compaction and subsequent compression into high ASD load tablets

Despite wide commercial application of hypromellose acetate succinate (HPMCAS) in spray-dried amorphous solid dispersion (ASD) drug products, little information is available in the references on downstream processing of spray-dried dispersions with HPMCAS. Poor flow and high dilution factor are a challenge in formulating spray-dried ASDs into tablets, leaving little space for other excipients facilitating binding and disintegration. Direct compression is not possible due to the poor powder flow of spray-dried ASDs. Moisture has to be avoided due to the plasticizing properties of water on the ASD, resulting in reduced stability of the amorphous state. Thus, dry granulation by roller compaction and subsequent tablet compression is the preferred downstream process. We report the investigation of downstream processing by roller compaction and tablet compression of a high load formulation with 75% of spray-dried amorphous solid dispersion (Nifedipine:HPMCAS 1:2). A head to head comparison of microcrystalline cellulose/croscarmellose (MCC/cl-NaCMC) as binder/disintegrant vs. MCC and low-substituted hydroxypropyl cellulose (L-HPC) as excipient for binding and disintegration showed improved re-workability of the formulation with MCC/L-HPC after roller compaction. Upon transfer to the rotary press, a 45% higher tensile strength of tablets is observed after dry granulation with MCC/L-HPC.

Application of Solid Dispersion Technique to Improve Solubility and Sustain Release of Emamectin Benzoate

The solid dispersion technique, which is widely used in the medical field, was applied to prepare a pesticide dosage form of emamectin benzoate (EM). The preparation, physicochemical characterization, aqueous solubility, release dynamics, photolytic degradation, bioactivity, and sustained-release effects of the prepared EM solid dispersions were studied by a solvent method, using polymer materials as the carriers. Water-soluble polyvinyl pyrrolidone (PVP) K30 and water-insoluble polyacrylic resin (PR)III were used as the carriers. The influence of various parameters, such as different EM:PVP-K30 and EM:PRIII feed ratios, solvent and container choices, rotational speed and mixing time effects on pesticide loading, and the entrapment rate of the solid dispersions were investigated. The optimal conditions for the preparation of EM-PVP-K30 solid dispersions required the use of methanol and a feed ratio between 1:1 and 1:50, along with a rotational speed and mixing time of 600 rpm and 60 min, respectively. For the preparation of EM-PRIII solid dispersions, the use of methanol and a feed ratio between 1:4 and 1:50 were required, in addition to the use of a porcelain mortar for carrying out the process. Under optimized conditions, the prepared EM-PVP-K30 solid dispersions resembled potato-like, round, and irregular structures with a jagged surface. In contrast, the EM-PRIII solid dispersions were irregular solids with a microporous surface structure. The results of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), ultraviolet (UV) spectrometry, and infrared (IR) spectrometry showed that the solid dispersions were formed by intermolecular hydrogen bonding. The solid dispersion preparation in PVP-K30 significantly improved the solubility and dissolution rate of EM, particularly the aqueous solubility, which reached a maximum of 37.5-times the EM technical solubility, when the feed ratio of 1:10 was employed to prepare the dispersion. Importantly, the wettable powder of EM-PVP-K30 solid dispersion enhanced the insecticidal activity of EM against the Plutella xylostella larvae. Furthermore, the solid dispersion preparation in PRIII afforded a significant advantage by prolonging the EM technical release in water at a pH below 7.0, especially when the PRIII content in solid dispersions was high. While the amplified toxicity of the wettable powder of EM-PRIII solid dispersions against the P. xylostella larvae showed no significant differences from that of the EM technical, the long-term toxicity under the field condition was much better than that of the commercially available EM 1.5% emulsifiable concentrate. Notably, solid dispersions with both the PVP-K30 and PRIII carriers reduced the effect of UV photolysis.

Hydration and Dispersion Forces in Hydroxypropylcellulose Phase Behavior

Many-body polarization and hydration forces can strongly affect the equilibrium structure and energetics of mixed phases. Accurately reproducing both forces presents a challenge to force field models because it requires balancing hydrogen bonding at short range with many-body orientational order and dispersive attraction at long range. This work reports the first comparison of experimental measurements of the pressure-area isotherm for hydroxypropylcellulose (HPC) against molecular dynamics results with four different force field models-united-atom, all-atom (OPLS and CHARMM), and Drude oscillator models. All force fields exhibit the experimentally determined, exponentially shaped repulsive force at short range. Above a critical temperature of about 40 °C and a lattice spacing of around 14 Å, HPC experiments show a reversible, heat-induced polymer aggregation into an ordered phase driven by loss of water. The nonpolarizable force fields do not display the critical point and instead show biphasic behavior at all temperatures tested. This indicates net attractive forces at intermediate lattice spacings. In contrast, the Drude polarizable force field shows positive osmotic pressure and a single, homogeneous phase over all temperatures and spacings tested. Analysis of structural data from our simulations provides several clues to help interpret these findings. Although all force fields show similar water-water hydrogen bond numbers in the mixed phase, the polarizable model predicts that water-HPC hydrogen bonds are much more favorable than HPC-HPC hydrogen bonds when polymers are dispersed. At high density, water is driven out and replaced by HPC-HPC hydrogen bonds. The polarizable force field shows that both effects have a stronger dependence on polymer density than any of the nonpolarizable models. Our observations support the conclusion that hydration forces are coupled to the polymer coordination number by local, structural waters and that long-range dispersive attraction is overestimated by pairwise additive models.

Preparation and Evaluation of Mosapride Citrate Dual-Release Dry Suspension

In this paper, a novel formulation of dual-release dry suspension of mosapride citrate (DRDS-MC) was designed which can be quickly released in the stomach while having sustained-release effect. Co-grinding mixture of mosapride citrate (MC) together with L-HPC as hydrophilic excipient was prepared in order to improve the solubility of MC. The co-grinding mixture was characterized by solubility studies, DSC, X-RD, SEM, FTIR, and size distribution before the preparation of the DRDS-MC. Then, the co-grinding mixture was used to prepare DRDS-MC via wet granulation method. The evaluation of DRDS-MC was focused on physicochemical properties, intestinal absorption, and pharmacokinetics. The results of DSC, X-RD, SEM, FTIR, and size distribution indicated that MC resides in co-grinding mixture with no crystalline changes, hydrogen bonds made L-HPC greatly improving the solubility of MC. Then, the dissolution of DRDS-MC reached 70% in pH 1.2 within 2 h, and the 12-h dissolution of MC in pH 6.8 was nearly 80%. The sedimentation volume after 3 h was 0.94 and redispersibility was good. The linear regression equation between in vitro release of DRDS-MC and intestinal absorption fraction in rats was: Y = 29.215 + 47.535*X (r = 0.952). At last, pharmacokinetic studies in beagle dogs demonstrated that DRDS-MC has prolonged effect compared with commercial formulation Gasmotin as a reference. All results indicated that the DRDS-MC could be quickly released in the stomach while having sustained-release effect.

Expanding the Application and Formulation Space of Amorphous Solid Dispersions with KinetiSol®: a Review

Due to the high number of poorly soluble drugs in the development pipeline, novel processes for delivery of these challenging molecules are increasingly in demand. One such emerging method is KinetiSol, which utilizes high shear to produce amorphous solid dispersions. The process has been shown to be amenable to difficult to process active pharmaceutical ingredients with high melting points, poor organic solubility, or sensitivity to heat degradation. Additionally, the process enables classes of polymers not conventionally processable due to their high molecular weight and/or poor organic solubility. Beyond these advantages, the KinetiSol process shows promise with other applications, such as the production of amorphous mucoadhesive dispersions for delivery of compounds that would also benefit from permeability enhancement.