Physicochemical and Pharmacokinetic Characterization of Amorphous Solid Dispersion of Meloxicam with Enhanced Dissolution Property and Storage Stability.

The aim of the present study was to develop amorphous solid dispersion (ASD) of meloxicam (MEL) for providing rapid onset of action. ASDs of MEL with polyvinylpyrrolidone (PVP) K-30 (MEL/PVP), HPC-SSL (MEL/HPC), and Eudragit EPO (MEL/EPO) were prepared. The physicochemical properties were characterized by focusing on morphology, crystallinity, dissolution properties, stability, and the interaction of MEL with coexisting polymers. MEL/EPO was physicochemically stable after storage at 40°C/75% RH for 30 days. In contrast, recrystallization of MEL was observed in MEL/PVP and MEL/HPC at 40°C/50% RH for 30 days. Infrared spectroscopic studies and (1)H NMR analyses of MEL/EPO revealed that Eudragit EPO interacted with MEL and reduced intermolecular binding between MEL molecules. Intermolecular interaction of drug molecules is necessary for the formation of crystalline. Thus, the interaction of MEL with Eudragit EPO and interruption of the formation of supramolecular interaction between MEL molecules might lead to the inhibition of crystal growth of MEL. Of all the MEL solid dispersions prepared, MEL/EPO showed the largest improvement in dissolution behavior. Oral administration of MEL/EPO to rats showed rapid and enhanced MEL exposure with a 2.4-fold increase in bioavailability compared with crystalline MEL. Based on these findings, MEL/EPO was physicochemically stable and provided a rapid onset of action and enhanced bioavailability after oral administration.

Nanosizing of poorly water soluble compounds using rotation/revolution mixer.

In this study, nanoparticles of various poorly water soluble compounds were prepared by wet milling that was carried out using a rotation/revolution mixer and zirconia balls. To be compared with Beads mill, rotation/revolution mixer has superior in very quick process (5 min) and needs very few amounts of zirconia balls (2.4 g) for pulverizing drugs to nanometer range. Phenytoin, indomethacin, nifedipine, danazol, and naproxen were selected as the standard poorly water soluble compounds. Various parameters of the rotation/revolution mixer were studied to decide the optimal pulverization conditions for the production of nanoparticles of the abovementioned compounds. The rotation/revolution speed, shape of the mixing vessel, amount of zirconia balls, and volume of the vehicle (methylcellulose solution) mainly affected the pulverization of the compounds. Using the mixer, phenytoin could be pulverized to nanoparticles within a few minutes. The particle size was confirmed by using a scanning electron microscope and a particle size analyzer. The crystallinity of the pulverized phenytoin particles was confirmed by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). It was observed that the pulverized phenytoin particles retained their crystallinity, and amorphous phenytoin was not detected. Particles of other poorly water soluble compounds were also reduced to the nanometer range by using this method.

Enhanced biopharmaceutical effects of tranilast on experimental colitis model with use of self-micellizing solid dispersion technology.

The present study aimed to clarify the applicability of a self-micellizing solid dispersion of tranilast (SMSD/TL) to the treatment of inflammatory bowel diseases (IBD) using an experimental colitis model. SMSD/TL with several loading amounts ranging from 10 to 50% was prepared using a wet-milling system. The physicochemical properties of SMSD/TL were evaluated in terms of the dissolution behavior, morphology, and particle size distribution. Animal studies were conducted to evaluate oral bioavailability in rats and anti-inflammatory effects in a rat model of chemically induced colitis. SMSD/TL with drug loading of 15% (SMSD/TL15) showed enhanced dissolution behavior at pH 1.2, compared with other tested other formulations. After the dispersion of SMSD/TL15 in deionized water, fine micelles formed with an average diameter of 137 nm. SMSD/TL15 (10 mg-TL/kg) exhibited about 147- and 34-fold greater value for Cmax and the area under the curve of plasma concentration vs. time than crystalline TL, respectively. Although the anti-inflammatory effect on the colitis model was very limited in the crystalline TL (2 mg/kg) group, inflammatory events, such as myeloperoxidase activity and thickening of the submucosa in colon tissues, were significantly suppressed in the SMSD/TL15 (2 mg-TL/kg) group. Based on these findings, SMSD/TL might be a more efficacious dosage option for improved IBD treatment.

Strategic application of self-micellizing solid dispersion technology to respirable powder formulation of tranilast for improved therapeutic potential.

PURPOSE: The present study aimed to develop an inhalable self-micellizing solid dispersion of tranilast (SMSD/TL) using poly[MPC-co-BMA] to improve the therapeutic potential and safety. METHODS: The safety of poly[MPC-co-BMA] in lungs was assessed using rat lung epithelium-derived L2 cells. SMSD/TL and respirable powder of SMSD/TL (SMSD/TL-RP) were prepared using a wet milling system and jet mill, respectively. The physicochemical properties of TL formulations were characterized in terms of dissolution, morphology, and particle size. Pharmacological and pharmacokinetic studies were also conducted on inhaled SMSD/TL-RP. RESULTS: The lactate dehydrogenase level from L2 cells treated with poly[MPC-co-BMA] was lower than that with polysorbate 80, a positive control. SMSD/TL showed enhanced dissolution behavior of TL. The jet milled SMSD/TL particles easily separated from the lactose carrier, and the particle size was suitable for inhalation. Compared with RP of TL, inhaled SMSD/TL-RP (100 µg-TL/rat) could more strongly suppress the inflammatory responses in antigen-sensitized rats. The TL level in plasma after intratracheal administration of SMSD/TL-RP at a pharmacological effective dose (100 µg-TL/rat) was ca. 4.2-fold lower than that after oral administration of TL solution at a clinical dose (1.67 mg/kg). CONCLUSION: SMSD/TL-RP might be an attractive dosage form to improve the anti-inflammatory effects and safety of TL.

Development of a novel nanoparticle formulation of thymoquinone with a cold wet-milling system and its pharmacokinetic analysis.

The present study aimed to develop a nanoparticle (NP) formulation of thymoquinone (TQ), a potent anti-oxidant chemical, with use of a cold wet-milling (CWM) system to improve its dissolution behavior and pharmacokinetic properties. The NP formulation of TQ (TQ/CWM) was prepared by CWM system, and its physicochemical properties were characterized in terms of particle size distribution, morphology, crystallinity, and dissolution. The photochemical properties of TQ were also examined upon UV/VIS absorption, reactive oxygen species (ROS) generation, and photostability. Pharmacokinetic studies were carried out in rats. Application of the CWM system to TQ led to successful development of nano-sized TQ. The mean diameter of TQ in TQ/CWM was calculated to be 143nm, and TQ particles in TQ/CWM were found to be amorphous. There was a marked improvement in dissolution rate compared with TQ. TQ showed significant generation of singlet oxygen and superoxide upon exposure to simulated sunlight, suggesting its high photoreactivity, and solid samples such as TQ and TQ/CWM exhibited higher photostability than TQ solution. In comparison with TQ, enhanced TQ exposure was observed with a ca. 6-fold increase of oral bioavailability, and the Tmax was shown to be a quarter. From these findings, the NP approach employing the CWM system might be a promising dosage option for improving the nutraceutical values of TQ.

Biopharmaceutical characterization of nanocrystalline solid dispersion of coenzyme Q10 prepared with cold wet-milling system.

The present study aimed to develop a nano-crystalline solid dispersion (CSD) of coenzyme Q10 (CoQ10) using a newly developed cold wet-milling (CWM) system to enhance the dissolution and biopharmaceutical properties of CoQ10. CSD formulations of CoQ10 were prepared by the CWM system, and their physicochemical properties were characterized in terms of morphology, crystallinity, particle size distribution, dissolution, and photostability. Application of the CWM system to CoQ10 led to successful development of a CSD formulation (CoQ10/CWM) with a mean CoQ10 diameter of ca. 129 nm, although a conventional wet-milling system failed due to evident formation of large particles. In comparison with crystalline CoQ10, marked improvement in the aqueous dissolution was seen for the CoQ10/CWM, with no significant decrease of photostability. Oral bioavailability and hepatoprotective effects of orally dosed CoQ10 samples were also evaluated in rats. After oral administration of CoQ10/CWM (100 mg CoQ10/kg) in rats, there appeared to be a similar Tmax value and 13-fold increase of bioavailability compared with crystalline CoQ10. In a rat model of acute liver injury, pretreatment with CoQ10/CWM (100 mg CoQ10/kg, twice) led to marked attenuation of hepatic damage as evidenced by decreased ALT and AST, surrogate biomarkers for hepatic injury, whereas crystalline CoQ10 was less effective. The CSD approach with the new CWM system might be a promising dosage option for improving the nutraceutical values of CoQ10.

Preparation and evaluation of high dispersion stable nanocrystal formulation of poorly water-soluble compounds by using povacoat.

In this study, we reported the application of Povacoat®, a hydrophilic polyvinylalcohol copolymer, as a dispersion stabilizer of nanoparticles of poorly water-soluble compounds. In addition, the influence of aggregation of the nanoparticles on their solubility and oral absorption was studied. Griseofulvin (GF) was used as a model compound with poor water solubility and was milled to nanoparticles by wet bead milling. The dispersion stability of GF milled with Povacoat® or the generally used polymers (polyvinylalcohol, hydroxypropylcellulose SSL, and polyvinylpyrrolidone K30) was compared. Milled GF suspended in Povacoat® aqueous solution with D-mannitol, added to improve the disintegration rate of freeze-dried GF, exhibited high dispersion stability without aggregation (D90 = ca. 0.220 µm), whereas milled GF suspended in aqueous solutions of the other polymers aggregated (D90 > 5 µm). Milled GF with Povacoat® showed improved aqueous solubility and bioavailability compared with the other polymers. The aggregation of nanoparticles had significant impact on the solubility and bioavailability of GF. Povacoat® also prevented the aggregation of the various milled poorly water-soluble compounds (hydrochlorothiazide and tolbutamide, etc.) more effectively than the other polymers. These results showed that Povacoat® could have wide applicability to the development of nanoformulations of poorly water-soluble compounds.

Development of nanocrystal formulation of meloxicam with improved dissolution and pharmacokinetic behaviors.

The present study aimed to develop nanocrystal formulations of meloxicam (MEL) in order to enhance its biopharmaceutical properties and provide a rapid onset of action. Nanocrystal formulations were prepared by wet-milling and lyophilization with hydrophilic polymers used as aggregation inhibitors. Aggregation inhibitors were selected based on high-throughput screening of crystal growth inhibition in supersaturated MEL solution. Supersaturation of MEL was observed in PVP K-30, HPC-SSL, and POVACOAT Type F solution. Although the particle size distributions of pulverized MEL with PVP K-30 (MEL/PVP), HPC-SSL (MEL/HPC), and POVACOAT Type F (MEL/POVA) were in the nanometer range following lyophilization, increases in micron-sized aggregates were observed after storage at 60°C for 21 days. The order of increased amount of aggregates was MEL/POVA≫MEL/HPC>MEL/PVP. These findings showed that hydrophilic polymers that inhibited crystal growth in supersaturated MEL solutions tended to prevent aggregation. The dissolution behavior of all nanocrystal formulations tested was markedly enhanced compared with that of unpulverized MEL. Oral administration of MEL/PVP showed a 2.0h shortened Tmax and a 5.0-fold increase in bioavailability compared with unpulverized MEL. These findings showed that the MEL/PVP mixture was physicochemically stable and provided a rapid onset of action and enhanced bioavailability after oral administration.

Self-micellizing solid dispersion of cyclosporine A with improved dissolution and oral bioavailability.

The present study aimed to develop a self-micellizing solid dispersion (SMSD) of cyclosporine A (CsA) using an amphiphilic block copolymer, poly[MPC-co-BMA], to improve the biopharmaceutical properties of CsA. The cytotoxicity of poly[MPC-co-BMA] was assessed in rat intestinal IEC-6 cells, and the pMB was less cytotoxic than polysorbate 80, a non-ionic surfactant with a wide safety margin. SMSD/CsA was prepared using a wet-milling system, and its physicochemical properties were characterized in terms of morphology, crystallinity, dissolution, particle size distribution, and stability. The SMSD/CsA exhibited immediate formation of fine micelles with a mean diameter of ca. 180 nm when introduced into aqueous media. There was marked improvement in the dissolution behavior of the SMSD/CsA compared with amorphous CsA. Even after storage at 40°C/75% relative humidity, the dissolution behavior of aged SMSD/CsA seemed to be almost identical to that of its freshly prepared equivalent, and CsA in aged SMSD/CsA was still in amorphous form. After oral administration of SMSD/CsA (10 mg CsA/kg) in rats, enhanced CsA exposure was observed with increases of Cmax and BA by ca. 11- and 42-fold, respectively, compared with those of amorphous CsA. The poly[MPC-co-BMA]-based SMSD formulation system might be an efficacious dosage option for CsA to achieve improvements in oral bioavailability.

Development of novel solid dispersion of tranilast using amphiphilic block copolymer for improved oral bioavailability.

The present study aimed to develop novel solid dispersion (SD) of tranilast (TL) using amphiphilic block copolymer, poly[MPC-co-BMA] (pMB), to improve the dissolution and pharmacokinetic behavior of TL. pMB-based SD of TL (pMB-SD/TL) with drug loading of 50% (w/w) was prepared by wet-mill technology, and the physicochemical properties were characterized in terms of morphology, crystallinity, dissolution, and hygroscopicity. Powder X-ray diffraction and polarized light microscopic experiments demonstrated high crystallinity of TL in pMB-SD/TL. The pMB-SD/TL exhibited immediate micellization when introduced to aqueous media, forming fine droplets with a mean diameter of ca. 122 nm. There was marked improvement in the dissolution behavior for the pMB-SD/TL even under acidic conditions, although the supersaturated TL concentration gradually decreased. NMR analyses demonstrated interaction between TL and pMB, as evidenced by the chemical shift drifting and line broadening. Pharmacokinetic behaviors of orally dosed TL formulations were evaluated in rats using UPLC/ESI-MS. After oral administration of pMB-SD/TL (10mg TL/kg) in rats, enhanced TL exposure was observed with increases of Cmax and AUC by 125- and 52-fold, respectively, compared with those of crystalline TL. From these findings, pMB-based SD formulation approach might be an efficacious approach for enhancing the therapeutic potential of TL.

Physicochemical and biopharmaceutical characterization of amorphous solid dispersion of nobiletin, a citrus polymethoxylated flavone, with improved hepatoprotective effects.

The present study aimed to develop an amorphous solid dispersion (SD) of nobiletin (NOB), a citrus polymethoxylated flavone, with the aim of improving its biopharmaceutical and hepatoprotective properties. SD formulation of NOB (NOB/SD) was prepared by wet-milling and subsequent freeze drying, and its stability and dissolution properties were characterized. The hepatoprotective effects and pharmacokinetic behavior of orally dosed NOB/SD were evaluated in rats. During the storage of NOB/SD for 4 weeks under accelerated conditions, there were no significant transitions in the appearance, particle size, and amorphousity of wet-milled NOB. In comparison with crystalline NOB, the NOB/SD exhibited significant improvement in the dissolution with a 10-fold higher dissolution rate. In a rat model of acute liver injury, repeated treatment with NOB/SD (2 mg NOB/kg) every 4 h led to marked attenuation of hepatic damage as evidenced by decreased ALT and AST, surrogate biomarkers for hepatic injury; however, crystalline NOB was found to be less effective. After oral administration of NOB/SD (2 mg NOB/kg) in rats, compared with crystalline NOB, improved pharmacokinetic behavior was observed with increases of bioavailability and hepatic delivery by ca. 7- and 6-fold, respectively, possibly leading to better hepatoprotection. Given the improved physicochemical and biopharmaceutical properties, the SD formulation strategy might be efficacious for enhancing the therapeutic potential of NOB.

Comparative studies on physicochemical stability of cyclosporine A-loaded amorphous solid dispersions.

The present study aimed to evaluate the physical stability on amorphous solid dispersion (SD) of cyclosporine A (CsA) employing hydroxypropyl cellulose (HPC). SD formulations (5-30% CsA) of CsA such wet-milled SD (WM/SD) and freeze-dried SD (FD/SD) were prepared, and both SD formulations were stored at 40 °C/75% relative humidity for 8 weeks. Transitions in morphology, dissolution behavior, crystallinity and thermal behavior of CsA were evaluated. There was at least 84-fold improvement in initial dissolution rate of SD formulations compared with that of amorphous CsA powder, although their dissolution rate was gradually decreased under accelerated conditions. In particular, aged FD/SD with a drug load of 30% exhibited highly limited dissolution as evidenced by 40% reduction of solubility after 8 weeks of storage. In contrast, aged WM/SD exhibited less reduction in dissolution rate compared with FD/SD. No significant changes were seen in crystallinity and thermal behavior after aging of SD formulations for 8 weeks; however, electron microscopic observations revealed aggregation of drug molecules/particles in the aged FD/SD, possibly leading to the reduced dissolution. From these findings, stability on CsA-loaded SD might be variable depending on the preparation methodology, and the wet-milling approach could be a viable option for preparing efficacious SD formulations with improved stability.

[Equivalence studies of pravastatin original and generic drugs by dissolution test].

There are various opinions regarding the different functions of original and generic drugs. We used the paddle method to perform dissolution tests on pravastatin sodium tablets (10 mg) to investigate the causes for these differences. We used water and buffer solutions adjusted to pH 1.2 (JP1) and pH 6.8 (JP2), which are described in the Japanese Pharmacopoeia. The pravastatin concentration was measured by UV spectroscopy and HPLC. There were significant differences in the percentages dissolved of original and generic drugs after 5 and 10 min. On the other hand, the dissolution behaviors using water and JP2 measured by HPLC were similar to the results obtained by UV spectroscopy. However, the percentage dissolved of pravastatin using JP1 decreased with time because pravastatin degraded in JP1. There were also significant differences in the pravastatin concentrations of the original and generic drugs at 5, 15, 30, and 45 min. Based on the above results, since the original drug has a slower dissolution rate than the generic drugs, it is necessary to be cautious about the degradation of pravastatin in the stomach and the bioavailability of pravastatin due to the different dissolution rates and the different residual amount of pravastatin in the stomach.

Development of high-energy amorphous solid dispersion of nanosized nobiletin, a citrus polymethoxylated flavone, with improved oral bioavailability.

Nobiletin (NOB), a citrus polymethoxylated flavone, attracts attention because of a wide range of pharmacological activities such as anti-inflammation, anticancer, and most notably ameliorative actions on memory impairment and ß-amyloid pathology. However, clinical use of NOB could be partly limited due to its poor solubility and bioavailability, which might necessitate high doses in order to reach therapeutic plasma concentrations in the central nervous system (CNS) after oral administration. In the present study, amorphous solid dispersion (SD) of nanosized NOB (NOB/SD) was prepared by wet-milling technique with the aim of improving dissolution behavior and pharmacokinetic properties of NOB. Physicochemical properties of the NOB/SD were characterized with focus on surface morphology, particle size distribution, dissolution, and crystallinity assessment. Wet-milled NOB particles in NOB/SD appeared to be amorphous with a diameter of approximately 270 nm, and there was marked improvement in the dissolution behavior compared with that of crystalline NOB. After oral administration of NOB/SD, higher exposure of NOB was observed with increases of bioavailability and CNS distribution by 13- and sevenfold, respectively, compared with those of crystalline NOB. These findings suggest that an amorphous, nanosized SD could be a viable option for enhancing the bioavailability and CNS delivery of NOB.

Improved dissolution and pharmacokinetic behavior of cyclosporine A using high-energy amorphous solid dispersion approach.

The aim of the present investigation is to develop solid dispersion (SD) formulations of cyclosporine A (CsA) for improving the oral bioavailability of CsA. Amorphous SDs of CsA with eight hydrophilic polymers were prepared with wet-mill employing zirconia beads. The physicochemical properties were characterized with a focus on morphology, crystallinity, thermal behavior, dissolution, and interaction of CsA with co-existing polymer. Although CsA molecules were found to be amorphous in all wet-milled formulations, some SD formulations failed to improve the dissolution. Of all CsA formulations, SD using polymer with HPC(SSL) exhibited the largest improvement in dissolution behavior. Pharmacokinetic profiling of orally dosed CsA in rats was carried out using UPLC/ESI-MS. After the oral administration of HPC(SSL)-based SD, enhanced CsA exposure was observed with increases in C(max) and AUC of ca. 5-fold, and the variation in AUC was ca. 40% less than that of amorphous CsA. Infrared spectroscopic studies suggested an interaction between CsA and HPC(SSL), as evidenced by the conformational transition of CsA. From the improved dissolution and pharmacokinetic data, the amorphous SD approach using wet-milling technology should lead to consistent and enhanced bioavailability, leading to an improved therapeutic potential of CsA.