To investigate theological properties of common hydrophilic gel excipients such as Carbopol based on viscosity, the viscosity was determined by rotation method and falling-ball method. Linear regression was made between ln(eta) and concentration, the slope of which was used to explore the relation between viscosity and concentration of different excipients. The viscosity flow active energy (E(eta)) was calculated according to Arrhenius equation and was used to investigate the relation between viscosity and temperature of different excipients. The results showed that viscosities measured by two methods were consistent. Concentration of guargum (GG) and hydroxypropylmethyl cellulose (HPMC) solution had a great influence on the viscosity, k > 5; while concentration of polyvinylpyrrolidone-K30 (PVP-K30) and polyethylene glycol 6000 (PEG6000) exerted a less effect on viscosity, k < 0.2; viscosity flow active energy of different excipients were close, which ranged from 30 to 40 kJ x mol(-1). Therefore, theological properties study could provide the basis for application of excipients and establish a foundation for the research of relation between excipients structure, property and function.
Excipients ; chemistry ; Gels ; chemistry ; Polyethylene Glycols ; chemistry ; Polyvinyls ; chemistry ; Povidone ; chemistry ; Rheology ; Temperature ; Viscosity

In this article, based on the relative references in the latest 8 years, we introduce briefly the origin, preparation and application of various injectable and absorbable gelling scaffold materials, and outline their advantages and disadvantages as localized gelling scaffold systems.
Absorbable Implants ; Biocompatible Materials ; Gels ; chemistry ; Injections ; Tissue Engineering ; methods

OBJECTIVETo prepare the nasal thermosensible gels of Chinese medicine Xingbi and study the release mechanism.

METHODThe gels were prepared by using P407 as the gel matrix and P188 and PEG 6000 were used to adjust the gelatination temperature. The formulations were screened by the method of orthogonal test. Mathematic models were used to imitate the drug release.

RESULT20% poloxmar 407, 2% poloxmar 188 and 2% PEG 6000 were suitable to Chinese medicine Xingbi thermosensitive gel in situ. Nasal thermosensible gels of Chinese medicine Xingbi was gelated at the temperature between 32-34 degrees C and the dissolution curves in vitro showed that the drug release could be best described by the Higuchi equation.

CONCLUSIONThe formulation of the nasal thermosensible gels of Chinese medicine Xingbi is reasonable and it is worth doing further research.

Chemistry, Pharmaceutical ; methods ; Drugs, Chinese Herbal ; chemistry ; pharmacokinetics ; Gels ; chemistry ; Humans ; Nose Diseases ; drug therapy ; Temperature

OBJECTIVETo prepare kappa-carrageenan-chitosan polyelectrolyte gel pellets and detect the effects of formulation and preparation factors on in vitro drug release from the pellets.

METHODThe K-carrageenan-chitosan polyelectrolyte gel pellets with baicalin as model drug were prepared by ionotropic gelation technique. The ratio of kappa-carrageenan/chitosan in pellets was determined with the composite of K-carrageenan and chitosan. The effects of the concentration of K-carrageenan, the ratio of drug/kappa-carrageenan, the concentration of gelling solution, gelling time and drying method on the release of pellets were determined by in vitro drug release.

RESULTThe mass ratio of K-carrageenan/chitosan in pellets was 6: 4. Release of the pellets in 0.1 mol x L(-1) HCl was about 10% for 2 hours and fast in PBS, indicating a typical sustained release property. The pellets released less with the increase in the concentration of K-carrageenan, the ratio of drug/kappa-carrageenan and the concentration of KCl. They also released less with the increase in gelling time, but showed little effect until 1 hour. The release of the pellets prepared by the freeze-drying method was much faster than those by vacuum drying and atmospheric drying methods which had little influence on drug release.

CONCLUSIONThe K-carrageenan-chitosan polyelectrolyte gel pellets had sustained release property. Their drug release rate could be regulated with different formulation and preparation factors.

Carrageenan ; chemistry ; Chemistry, Pharmaceutical ; Chitosan ; chemistry ; Desiccation ; Drug Carriers ; chemistry ; Electrolytes ; chemistry ; Gels ; Microspheres ; Potassium Chloride ; chemistry ; Time Factors

OBJECTIVETo optimize formulas of Quban gel.

METHODThe U6 (6(2) x 3) uniform design was adopted to optimize gel formulas, with rheological parameters, such as viscosity and yield value in room temperature, viscosity and yield value in average temperature of skin, thixlotropy.

RESULTThe optimum proportion of matrix was made of 1.0 g carbomer 940, 5 mL glycerin and pH value 5-6.

CONCLUSIONThe regression model for gel matrix quality and gel rheological parameters was established to directly reflect the impacting effect of various factors, and provide certain preference basis for the screening of gel matrix formulas. Quban gel prepared by the method was evenly distributed, moderately viscous and highly thixotropic

Chemistry, Pharmaceutical ; methods ; Drugs, Chinese Herbal ; chemistry ; Gels ; Quality Control ; Regression Analysis ; Viscosity

Present study used dip-coating techniques to fabricate ultrathin nano-HA coating on titanium in organic sol-gel of Ca (NO3)2. 4H2O and PO(CH3)3 and inorganic sol-gel of Ca (NO3)2. 4H2O and (NH4)2HPO4. Scanning electron microscope (SEM) and grazing-incidence X-ray diffraction (XRD) were used to observe the morphology and distribution of crystallite size (D) and lattice strain (epsilon) of ultrathin nano-HA coating. After heated at 400 degrees C, the apatite structure of coatings on titanium began to appear. At heating temperature of 400 degrees C-600 degrees C, the effect of heating temperature on D and epsilon of both coatings was obvious. Precursor types significantly affected the particle diameters of nano-HA coatings, which were 25-40 nm for organic sol-gel and about 100 nm for inorganic sol. The thickness of ultrathin nano-HA coatings was 2.5 microm for organic sol-gel and 5 microm for inorganic sol and morphology of interfaces between coating and titanium was intact and homogenous.
Coated Materials, Biocompatible ; chemical synthesis ; chemistry ; Durapatite ; chemical synthesis ; chemistry ; Gels ; Nanostructures

OBJECTIVETo establish the analytical method for the release kinetic (RK) of Aconitum Brachypodum gel based on the nonlinear mixed effect model (NLMEM), in order to rationally evaluate the drug release process and explain the release mechanism.

METHODThe zero-order kinetic model containing for non-corroded drug system with the random effect was taken as the base model. The fixed effect and random effect factors impacting the drug release were analyzed by PROC NLMIXED of SAS to establish the final typical model. Subsequently, 10 training subsets were randomly extracted from the primary data to respectively their RK models, calculate the corresponding predicted root-mean-square error and average relative error, and evaluate the model stability and prediction accuracy.

RESULTThe burst effect F0 had a very significant effect on the RK model. Among the component factors, carbopol 940 showed an obvious effect on the inherence release speed constant k0 and the concentration gradient change constant a, with different variations on the basis of dosage range. The random effect factors of k0 and a had a significant impact. The final RK model was proved to be stable, effective and reliable in the cross validation.

CONCLUSIONThe drug release kinetic analysis method could be used to rationally evaluate the drug release process and explain the release mechanisms.

Aconitum ; chemistry ; Drugs, Chinese Herbal ; chemistry ; Gels ; Kinetics ; Monte Carlo Method ; Nonlinear Dynamics

To evaluate the traits and rheological properties of thermosensitive in situ gel of Yihuang Decoction and its common gel for vaginal use, and predict the release behavior of Yihuang Decoction in situ gel in vitro. Poloxamer was used as thermosensitive material to prepare Yihuang Decoction vaginal in situ gel, and Yihuang Decoction common gel was prepared with carbopol. Then the differences of the two gels before and after diluting with vaginal fluid were compared. The rheological parameters of Yihuang Decoction in situ gel and its common gel were determined with Anton Paar MCR102 rheometer. In addition, berberine hydrochloride was selected as an index component to evaluate the in vitro release properties of Yihuang Decoction vaginal thermosensitive in situ gel. Yihuang Decoction vaginal thermosensitive in situ gel was Newtonian fluid under low-temperature conditions, which was yellow and transparent. After reaching the gelling temperature of 24.5 ℃, it became semi-solid, pseudoplastic fluid. The gelling temperature was predicted to be 37 ℃, and the phase transition time was 30 s after diluting with simulated vaginal fluid. However, the rheological properties of Yihuang Decoction common gel had no significant changes with temperature. Compared with in situ gel, the color of common gel was darker and more translucent. Besides, its mobility was stronger after diluting with simulated vaginal fluid. The in vitro release study showed that the kinetic behavior of berberine hydrochloride in Yihuang Decoction vaginal thermosensitive in situ gel was matched with the Higuchi equation. Through simulation of vaginal administration, physical properties and dynamic rheological parameters were used to intuitively and scientifically evaluate the two gels. Compared with the common gel, the thermosensitive in situ gel could quickly attached to the vaginal mucosa and release drug, and thus was more suitable for developing vaginal administration of Yihuang Decoction, which also provides references for studying new vaginal preparation of Yihuang Decoction.
Administration, Intravaginal ; Drugs, Chinese Herbal/chemistry* ; Female ; Gels/chemistry* ; Humans ; Poloxamer ; Rheology ; Temperature ; Viscosity

To develop an ophthalmic preparation of Shedan, an in situ forming gel was prepared with the formulation containing 18% of poloxamer 407 and 5% of poloxamer 188 by response surface designs plus central composite designs. The rheology results showed that LVE range gamma should limited within 0.5%, Shedan high-frequency region, and the thixotropy recovery time is less than 5 seconds. The phase transition temperature was 33.25 °C according to curve of storage modulus and loss modulus determined by temperature scanning. Surface tension and osmometer of it determined by surface tension meter and dew point osmometer were 36.43 mN · m(-1), and 320.6 mOsm · kg(-1), respectively. Fluorescein sodium was selected as the marker to monitor the corneal residence time, and the results showed that Shedan gel could prolong drug residence for 180 min. In line with zero-order kinetics, releases of muscone and salvianolic acid B in vitro depends on gels erosion. The results of rabbit ocular irritation experiments suggested that Shedan in situ forming gel was biocompatible and nonirritant. In conclusion, a novel Shedan in situ forming gel was developed and characterized for potential drug treatment of retinal vein occlusion.
Animals ; Benzofurans ; chemistry ; Cycloparaffins ; chemistry ; Female ; Gels ; chemistry ; Male ; Ophthalmic Solutions ; Poloxamer ; chemistry ; Rabbits ; Retinal Vein Occlusion ; drug therapy ; Viscosity

Now the layer-by-layer self-assembling (LbL) technique has become an attention-getting reparative methodology for ultrathin film formation. Many scientists in different academic areas including bioengieering, medical science, drug controlled release, optoelectronics dive into this technology. Among of them, carriers with structures which can be flexibly controlled are more useful since functional structure units can be assembled in layer-by-layer fashion, which is simplicity, chemical mildness, concealment, can achieve targeted drug delivery and so on. In this review, we have discussed the advantage, development, influential factors and applications of LbL. We have focused on reviewing the applications and perspective of nanoparticles, microgels and capsules were both fabricated via the LbL assembling at drug delivery.
Capsules ; chemistry ; Drug Carriers ; chemistry ; Drug Compounding ; methods ; Drug Delivery Systems ; methods ; Gels ; chemistry ; Nanoparticles ; chemistry ; Particle Size