Coamorphous combinations of poorly water-soluble drugs dabigatran etexilate mesylate and tadalafil for improving dissolution and physical stability / 中国药科大学学报

@#Dabigatran etexilate mesylate(DE)and tadalafil(TD)are BCS class II drugs with poor water solubility. 〓 In this study coamorphization technique was used to improve their solubilities/dissolutions and hence to enhance their oral absorptions. The coamorphous DE-TD were prepared by solvent-evaporation method and characterized by PXRD, DSC, FTIR and TGA. In addition, dissolution behavior and physical stability were also investigated. Only halo pattern and a single Tg of 119 °C was observed on the PXRD and DSC of the co-evaporated product, respectively, indicating the formation of coamorphous DE-TD. FTIR result suggested that a hydrogen bond was probably formed between N-H group of DE and C==O group of TD. In comparison to crystalline counterparts, coamorphous DE-TD showed a significantly improved intrinsic dissolution rate and prolonged supersaturation time in intrinsic dissolution and supersaturation dissolution studies, respectively. No crystallization was observed under affecting factors testing(30 days)as well as long-term and accelerated stability testing(90 days)for the prepared coamorphous DE-TD under 25°C/60%RH or 40°C/75%RH, while amorphous DE crystalized at 10 days under 25 ℃/75% RH.

Improvement of in vitro dissolution and physical stability for spironolactone solid dispersion formulated with Soluplus / 药学学报

Spironolactone, a class II drug of the biopharmaceutics classification system, has low oral bioavailability due to poor solubility. Spironolactone solid dispersions were prepared using the solvent method in order to improve its aqueous solubility. Optimization studies of spironolactone solid dispersions were performed using in vitro dissolution tests. Differential scanning calorimetry, X-ray diffraction and Fourier transform infrared were used to investigate the physical state of the drug in carrier materials and to detect the possible interactions between the drug and carrier materials in the solid dispersions. In addition, stress tests were employed to elucidate the key factors which have influence on the stability of the spironolactone solid dispersions. Results showed that spironolactone in the solid dispersions formulated with Soluplus and HPMC-E5 were both in amorphous state and the hydrogen bonds between the drug and carrier materials were formed in the solid dispersion. Therefore, the in vitro dissolution of spironolactone was also significantly enhanced. Stress tests demonstrated that the physical stability of spironolactone solid dispersions prepared with Soluplus was greatly improved compared to those formulated with HPMC-E5. Thus, spironolactone solid dispersion formulated with Soluplus using the solvent method could be used to improve the in vitro dissolution and stability of poorly soluble drugs.

Midazolam and haloperidol for palliative sedation: physicochemical stability and compatibility of parenteral admixtures

This study was done to determine the time while the binary admixtures with midazolam and haloperidol drugs are administered by perfusion to the patients in the clinical routine. Samples with different concentrations of both drugs were prepared following the usual clinical practice. Solvents used were 0.9 % sodium chloride solution and 5% dextrose, and viaflo plastic bags were used as the containers of the admixtures. Samples were not protected from light and were stored at 20 ºC or at 4 ºC. Compatibility and physicochemical stability were studied by visual inspection, turbidity measurement, pH determination and ultraviolet detection high performance liquid chromatography (UV-HPLC) was used to determine midazolam and haloperidol concentrations. The assay was validated following the FDA and EMA guidelines. Darunavir was used as internal standard (IS). For the studied admixtures, turbidity measurements and pH determinations showed little changes in function of the time. Haloperidol and midazolam concentrations determined by HPLC are within the acceptable range of drug concentrations, which are considered stable for four days in case of admixtures stored at 20 ºC and for seven days for refrigerated admixtures. Taking into account the microbiological risk matrix, the compatibility and the chemical and microbiological stability of the midazolam and haloperidol in the co-administered admixtures in viaflo plastic bags with 0.9 % sodium chloride solution and 5% dextrose can be set as 48 hours when samples are stored at 20 ºC and one week if they are refrigerated.

Physical Stability Evaluation of Glycyrrhetinic Acid Derivatives-Mediated Liposomes / 中国药学杂志

OBJECTIVE: To evaluate the physical stability of glycyrrhetinic acid derivatives-mediated coumarin 6(Cou6) liposomes and confirm the applicability of different stability tests on liposomes. METHODS: Film dispersion-ultrasonic method was used to prepare Cou6 liposomes, PEG-modified liposomes and glycyrrhetinic acid-mediated liposomes. The stability constants, membrane stability, serum stability and leakages of the six kinds of liposomes were studied. RESULTS: The physical stability of the liposomes without modification was poor. As for the glycyrrhetinic acid-mediated liposomes, the stability constants at 15 min were 5.37-7.32 and the concentrations of Triton X-100 were 0.207‰-0.380‰ when half liposome membranes were destroyed. The serum stability in 24 h and leakages in 7 or 14 d showed good stability with little change. CONCLUSION: The physical stability is one of the key pharmaceutical properties of liposomes. The stability constant, serum stability and leakage tests and the method of membrane stability we have established can be used to study the stability of liposomes.

Preparation of tadalafil-dapoxetine coamorphous complex with evaluation of dissolution and physical stability / 药学学报

Tadalafil (TD), a phosphodiesterase-5 inhibitor for the treatment of erectile dysfunction, has a low oral bioavailability due to its extremely poorly aqueous solubility. The aim of this study was to enhance its solubility and dissolution by coamorphization with dapoxetine (DP), a selective serotonin reuptake inhibitor to manage premature ejaculation. Coamorphous TD-DP (molar ratio, 1:1) was prepared by solvent-evaporation method and characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). The supersaturated dissolution of TD from coamorphous TD-DP was investigated in various aqueous media and compared to that of crystalline TD. In addition, physical stability of coamorphous system was also evaluated under the conditions of 40℃/75% relative humidity (RH) and 25℃/60% RH for 90 days. DSC thermogram and PXRD pattern indicated the formation of the coamorphous TD-DP. In comparison to original TD crystal, the dissolution of TD from coamorphous system were significantly enhanced in various media (water, 0.01 mol·L-1 HCl and pH 4.5 phosphate buffer). In addition, no crystallization phenomenon of the prepared coamorphous system was observed until 90 days' storage under 25℃/60% RH. However, when temperature and humidity were increased to 40℃/75% RH, the coamorphous TD-DP was recrystallized easily.

Physical stabilization of amorphous itraconazole in solid dispersions for improved dissolution profile.

The main objective of the present investigation was to improve dissolution efficiency and stabilize amorphous form of itraconazole (ITR) through formulation of ternary solid dispersion system (SDs) with polyvinylpyrrolidone K30 (PVP K30) and sylysia®350 using spray drying technique. The prepared ternary SD system was characterized for solid state properties, in vitro dissolution efficiency and accelerated stability study at 40 °C/75% RH for the period of 3 months to explore extent of stabilization of amorphous itraconazole (AITR). Surprisingly, AITR was found to have no significant improvement in its dissolution characteristics compared to pure drug. The formation of cohesive supercooled liquid state might be the reason for poor solubility. Hence a combined approach of SD system with an antiplasticizing agent and surface adsorption technique was employed to prevail over functional inabilities of AITR. The binary and ternary SDs of AITR were prepared employing PVP K30 as antiplasticizer and/or sylysia®350 as adsorbent in the ratio 1:1:1 w/w using spray drying technique. The prepared systems have shown significant improvement in dissolution characteristics when compared to pure drug. Accelerated stability studies confirmed the absence of crystallization events over a period of 3 months endorsing excellent stabilization of AITR.

Investigation of two kinds of solidification methods for felodipine nanosuspension: flocculation versus lyophilization / 中国药学杂志

OBJECTIVE: To solve the stability problem of felodipine nanosuspension which is a physically unstable colloidal dispersion by solidification method.

Development, physical-chemical stability and rheological behavior of silicones formulations containing Dimethylaminoethanol (DMAE).

The aim of this paper was to develop formulations increased of DMAE and evaluate their physical-chemical stability and rheological behavior. Eleven formulations containing 3% DMAE pidolate or 3% DMAE acetamidobenzoate were developed and both preliminary stabilities tests and rheological measurements were carried out. They were considered stable during all period of study. The type of DMAE did not modify the viscosity of the emulsion and all presented pseudoplastic behavior with hysteresis area. An increase of hysteresis area could be observed with DMAE addition. The results point that the type of DMAE can influence the physical stability of the final product.

Physical stability of arginine-glycine-aspartic acid peptide coated on anodized implants after installation

PURPOSE: The aim of this study was to evaluate the stability of arginine-glycine-aspartic acid (RGD) peptide coatings on implants by measuring the amount of peptide remaining after installation. MATERIALS AND METHODS: Fluorescent isothiocyanate (FITC)-fixed RGD peptide was coated onto anodized titanium implants (width 4 mm, length 10 mm) using a physical adsorption method (P) or a chemical grafting method (C). Solid Rigid Polyurethane Foam (SRPF) was classified as either hard bone (H) or soft bone (S) according to its density. Two pieces of artificial bone were fixed in a customized jig, and coated implants were installed at the center of the boundary between two pieces of artificial bone. The test groups were classified as: P-H, P-S, C-H, or C-S. After each installation, implants were removed from the SRPF, and the residual amounts and rates of RGD peptide in implants were measured by fluorescence spectrometry. The Kruskal-Wallis test was used for the statistical analysis (alpha=0.05). RESULTS: Peptide-coating was identified by fluorescence microscopy and XPS. Total coating amount was higher for physical adsorption than chemical grafting. The residual rate of peptide was significantly larger in the P-S group than in the other three groups (P<.05). CONCLUSION: The result of this study suggests that coating doses depend on coating method. Residual amounts of RGD peptide were greater for the physical adsorption method than the chemical grafting method.

New trends in the co-crystallization of active pharmaceutical ingredients.

Pharmaceutical materials science being a fundamental branch that continuously provides important insights, theories, and technologies to formulation sciences. The recent advances in this area have brought the possibility to produce pharmaceutical materials by design. In particular, the formation of co-crystals, i.e. crystalline molecular complexes of twoor more neutral molecules, represents a potential route to achieve pharmaceutical materials with improved properties of interest, including dissolution rate and stability under conditions of high relative humidity. Co-crystals consists of API and a stoichiometric amount of a pharmaceutically acceptable co-crystal former. Pharmaceutical co-crystals are nonionic supramolecular complexes and can be used to address physical property issues such as solubility, stability and bioavailability in pharmaceutical development without changing the chemical composition of the API. These can be constructed through several types of interaction, including hydrogen bonding, pi-stacking, and van der Waals forces. Phase transformations induced during processing/storage affects the mechanisms of conversion of crystalline drugs to co-crystals. Pharmaceutical co-crystals considered better alternatives to optimize drug properties could play a major part in the future of API formulation and can be employed for chiral resolution. This review introduces co-crystals as an emerging class of pharmaceutical materials, focusing on the experimental methods applicable to their crystallization. In addition, the examples illustrating how the co-crystal approach can be utilized to enhance the specific properties of pharmaceutical solids, such as dissolution rate of poorly-water soluble APIs and physical stability of moisture-labile APIs.