[The swelling behavior of choline fenofibrate hydrogel matrix tablets using dynamic image analysis].

The purpose of this study is to investigate the effects of formulation on the swelling behavior of choline fenofibrate hydrogel matrix tablets and reveal the relation between swelling property and release profile using dynamic image analysis. The volume swelling ratio (SR) and height/width (k) could evaluate the swelling behavior of matrix tablets well. The mount of hydroxypropyl methylcellulose (HPMC) and the ratio between K15M and K4M affected the volume swelling ratio, while PVP didn't. The three factors all impacted k, which was an indicator of the strength of the gel formed by HPMC. The accumulative release ratio and SR, the rate of swelling and the rate of release were compared. The proper model equations were established for the results with an excellent correlation. The results prove that there is a strong relevance between the swelling behavior and release property. This study provides a guideline in the study design for hydrogel matrix tablets.

[Preparation and properties of thermosensitive in situ gel for ophthalmic formulation containing pearl hydrolyzate].

The study was designed to generate an ophthalmic thermosensitive in situ gel with improved mechanical and mucoadhesive properties that may prolong the retention time to enhance the bioavalability of pearl hydrolyzate. The gene was comprised of poloxamer 407, poloxamer188 and Carbopol 934, which were optimized by central composite design and response surface methodology. The rheological properties, transcorneal permeability, retention time and in vitro release behaviors of the optimal gel formulation were investigated. The gel was Newtonian liquid at 25 ℃ and performed as a semisolid gel with non-Newtonian liquid property with a gelation time of 13 s at 35 ℃. Compared with a conventional eye drops, the ophthalmic in situ gel exhibited a sevenfold increase in retention with a sustained release behavior, which was observed with suitable permeability coefficient at 5.58 cm·s-1. In conclusion, the new gel of pearl hydrolyzate prolonged the release duration of drug, which may decrease the frequency of administration of pearl hydrolyzate.

[Determination of contact angle of pharmaceutical excipients and regulating effect of surfactants on their wettability].

To study the effects of surfactants on wettability of excipients, the contact angles of six types of surfactants on the surface of two common excipients and mixture of three surfactants with excipients were measured using hypsometry method. The results demonstrated that contact angle of water on the surface of excipients was associated with hydrophilcity of excipients. Contact angle was lowered with increase in hydrophilic groups of excipient molecules. The sequence of contact angle from small to large was starch < sodium benzoate < polyvinylpyrrolidone < sodium carboxymethylcellulose < sodium alginate < chitosan < hydroxypropyl methyl cellulose

[The rheology properties of common hydrophilic gel excipients].

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.

Ibuprofen ion-exchange fiber complex: improved dissolution and gastric tolerance based on ion exchange.

The purpose of the present study is to develop a novel method to improve the dissolution of water-insoluble drug ibuprofen and the gastric tolerance of this non-steroidal anti-inflammatory drug which has potentially serious gastrointestinal side effects. This method is based on ion exchange of ion-exchange fibers. Water-insoluble drug ibuprofen was dispersed in deionized water, and then the ion-exchange fibers in OH(-) type was immersed in it. Ibuprofen and the active groups of the ion-exchange fibers combined into ion pairs based on the acid-base reaction. This drug carrier did not release drugs in deionized water, but in water solution containing other ions it would release the drugs into the solution by ion exchange. Confirmed by the X-ray diffraction and the scanning electron microscopy, the ibuprofen combined onto the ion-exchange fibers was in a highly molecular level dispersed state. The improved dissolution of ibuprofen ion-exchange fiber complexes is likely to originate from this ibuprofen's highly dispersed state. Due to this, ibuprofen's highly dispersed state, ibuprofen ion-exchange fiber complexes significantly decreases the gastrointestinal side effects of ibuprofen by avoiding the solid ibuprofen's educing. The present study showed that ibuprofen ion-exchange fiber complexes have the two-fold advantages. One is to improve the dissolution of ibuprofen. The other is to decrease the ibuprofen's gastrointestinal toxicity.

[The preparation and kinetic study on enzymatically-controlled drug release of isotretinoin/amylose inclusion complex].

The inclusion complex of isotretinoin was prepared by sealed-control temperature method and amylose was used as carrier. The formation of inclusion complex was confirmed by powder X-ray diffraction and DSC. The equation of enzymatically-controlled drug release was established by kinetic theory, and the release characteristic of drug was confirmed by using the kinetic equation. The results show that the drug release was attributed to first order reaction without alpha-amylase. However, with alpha-amylase, the drug release was an acceleration process by the effect of both dissociation and enzymatic hydrolysis simultaneously. The research indicates that drug release from the inclusion complex was modulated by the addition of alpha-amylase.

Modulating drug loading and release profile of beta-cyclodextrin polymers by means of cross-linked degree.

The purpose of the present study is to use beta-cyclodextrin polymers (beta-CDP) with different cross-linked degree (CLD) to form inclusion complexes with ibuprofen and examine the effects of structural and compositional factors of beta-CDP on its drug loading and release behaviors. A series of beta-CDP with different CLD were synthesized and characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and 13C NMR spectrum. The beta-CDP was systemically characterized for the relation between the CLD of beta-CDP and the drug loading and release as well. The results of FT-IR and 13C NMR showed that similar peak-shaped vibration of beta-CDP and beta-CD implies that the polymer keeps the original characteristic structure of beta-CD. The CLD of the beta-CDP played a critical role in the drug loading and release, increasing the CLD resulted in reduction of drug loading, but increase in drug release.

[Kinetic study on dissociation of amylose/salicylic acid compound using non-isothermal method].

The inclusion compound of amylose and salicylic acid (SA) was prepared by a sealed temperature control method, and the formation of the inclusion compound was confirmed by IR spectrum and powder X-ray diffraction. The kinetic parameters of dissociation of amylose/SA compound were studied by the nonisothermal method which was defined as a relationship between the dissociation ratio and time. The values of activation energy (Ea) and frequency factors (InA) were calculated by a nonlinear least-square method. In this study, the formation of the inclusion compound of amylose/SA was confirmed by IR spectrum powder X-ray diffraction. SA existed in a molecule form in the spiral stouction of amylose. The dissociation of amylose/SA compound was attributed to first order reaction. The values of Ea calculated by the nor-isothermal method were 21.71 and 22.41 kJ x mol(-1) at heating rate 5 and 10 degrees C x h(-1), respectively. The corresponding isothermal method value of Ea was 22.17 kJ x mol(-1); the calculated InA values were 9.32 and 10.08 at heating rate 5 and 10 degrees C x h(-1), respectively. The corresponding isothermal method lnA value was 9.26. The results were in good agreement with Ea values and lnA values by isothermal method. These results indicated that the non-isothermal method described in this study could be adequately used for the stability study of inclusion compound and was a rapid and accurate method for the determination of kinetic parameters.

Pharmacokinetic studies of meloxicam following oral and transdermal administration in Beagle dogs.

AIM: The potential for topical delivery of meloxicam was investigated by examining its pharmacokinetic profiles in plasma and synovial fluid following oral and transdermal administration in Beagle dogs. METHODS: The experiment was a two-period, crossover design using 6 Beagle dogs. Meloxicam tablets were administered orally at a dose of 0.31 mg/kg, and meloxicam gel was administered transdermally at a dose of 1.25 mg/kg. Drug concentrations in plasma and synovial fluid were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The pharmacokinetic parameters were calculated using the Topfit 2.0 program. RESULTS: The pharmacokinetic results showed that AUC(0-t) (23.9+/-8.26 microg.h.mL(-1)) in plasma after oral administration was significantly higher than after transdermal delivery (1.00+/-0.43 microg.h.mL(-1)). In contrast, the ratio of the average concentration in synovial fluid to that in plasma following transdermal administration was higher than that for an oral delivery. The synovial fluid concentration in the treated leg was much higher than that in the untreated leg, whereas the synovial fluid concentration in the untreated leg was similar to the plasma concentration. CONCLUSION: The high concentration ratio of synovial fluid to plasma indicates direct penetration of meloxicam following topical administration to the target tissue. This finding is further supported by the differences observed in meloxicam concentrations in synovial fluid in the treated and untreated joints at the same time point. Our results suggest that transdermal delivery of meloxicam is a promising method for decreasing its adverse systemic effects.Acta Pharmacologica Sinica (2009) 30: 1060-1064; doi: 10.1038/aps.2009.73; published online 8 June 2009.

Development and evaluation of a pH-dependent sustained release tablet for irritable bowel syndrome.

The overall objective of this study was to develop a pH-dependent sustained release tablet formulation of a model drug, tegaserod maleate (TM), which is a poorly water soluble and acid labile drug in gastric milieu. The formulation's goal was to allow the dosage form to pass through the stomach intact, start disintegrating in the upper small intestine and slowly release the active in a controlled manner. Partition coefficient, contact angle and drug-excipient compatibility were investigated as part of the preformulation studies. A pH-dependent sustained release tablet was prepared using a combination of Eudragit L100 and Eudragit S100. The effects of solubilizer, disintegrant, binder, coating polymer concentration, pore former, and plasticizer on the drug release rate were determined. The results demonstrated that approximately 90% of the drug was released in a sustained release manner in the pH 6.8 phosphate buffer within 12 h while no drug was detected when subjected to drug release studies in 0.1 mol/L hydrochloric acid for 2 h. The drug release mechanism involved stress points and/or pore formation in the coated film. The coated tablets were stable at 40 degrees C/75% RH for 3 months. These results highlighted the feasibility of this coated tablet system containing TM, which may contribute to the successful treatment of irritable bowel syndrome.

Cloud point extraction-HPLC method for determination and pharmacokinetic study of flurbiprofen in rat plasma after oral and transdermal administration.

A method based on cloud-point extraction (CPE) was developed for the determination of flurbiprofen (FP) in rat plasma after oral and transdermal administration by high-performance liquid chromatography coupled with UV detection (HPLC-UV). The non-ionic surfactant Genapol X-080 was chosen as the extract solvent. Variables parameter affecting the CPE efficiency were evaluated and optimized. Chromatography separation was performed on a Diamond C(18) column (4.6 mm i.d. x 250 mm, 10 microm particle size) by isocratic elution with UV detection at 254 nm. The assay was linear over the range of 0.2-50 and 0.1-10 microg/ml for oral and transdermal administration, respectively, and the lower limit of quantification (LLOQ) was 0.1 microg/ml. The extraction recoveries were more than 84.5%, the accuracies were within +/-3.8%, and the intra- and inter-day precisions were less than 10.1% in all cases. After strict validation, the method indicated good performance in terms of reproducibility, specificity, linearity, precision and accuracy, and it was successfully applied to the pharmacokinetic study of flurbiprofen in rats after oral and transdermal administration.

In vitro and in vivo evaluation of tegaserod maleate pH-dependent tablets.

The purpose of this study was to prepare tegaserod maleate (TM) pH-dependent tablets and evaluate their advantages as a sustained release delivery system. TM, insoluble in water and unstable in gastric milieu, was formulated into pH-dependent tablets coated with combinations of two methacrylic acid copolymers - Eudragit L100 and Eudragit S100. The influence of core tablet compositions, polymer combination ratios and coating levels on the in vitro release rate of TM from coated tablets was investigated. The optimum formulation was evaluated for in vitro release rate and in vivo bioavailability study on beagle dogs. In addition, physico-chemical properties of the drug, including solubility at different pH and temperatures, and dissociation constant were determined. The results showed that no drug was released in 0.1 mol/L hydrochloric acid within 2h, and about 90% of the drug was released in the pH 6.8 phosphate buffer within 12h in a sustained manner. The pharmacokinetic investigation showed that TM pH-dependent tablets exhibited a sustained plasma concentration, a lag time of approximately 2.3h and a relative bioavailability of 159% compared to plain tablets. A close correlation existed between the in vitro release rate of the pH-dependent system and its in vivo absorption percentage. The results of the present study have demonstrated that the pH-dependent tablet system is a promising vehicle for preventing rapid hydrolysis in gastric milieu and improving oral bioavailability of TM for the treatment of irritable bowel syndrome.

[LC-MS/MS determination of budesonide in dog plasma].

A liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of budesonide in dog plasma. Budesonide and the internal standard triamcinolone acetonide were separated from plasma by alkalinized liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a Capcell Pak C18 MG column with the mobile phase consisted of acetonitrile -5 mmol x L(-1) ammonium acetate (60:40, v/v) at a flow-rate of 0.50 mL x min(-1). A tandem mass spectrometer equipped with electrospray ionization source was used as detector and operated in the negative ion mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions m/z 489 --> m/z 357 and m/z 493 --> m/z 413 for budesonide and the internal standard, respectively. The linear calibration curves were obtained in the concentration range of 25.0-2000 pg x mL(-1). The lower limit of quantification was 25.0 pg x mL(-1). The intra- and inter-day relative standard deviation over the entire concentration range was less than 15%. The accuracy was in the range of -8.1% to -1.7% in terms of relative error. The method was applied to a pharmacokinetic study of budesonide controlled-release capsules in Beagle dogs. Maximal budesonide plasma level was observed after (3.5 +/- 3.3) h and the Cmax was (786 +/- 498) pg x mL(-1) after a single oral administration of 9 mg budesonide capsules, Cmax was increased to (2142 +/- 1515) pg x mL(-1) after multiple oral administration (9 mg x 5 d) of budesonide capsules. This method was selective and rapid, and the sensitivity was sufficient for the purpose of the pharmacokinetic study of budesonide controlled-release formulation.

Pharmacokinetics of clarithromycin citrate salt after oral administration to beagle dogs and food effects on its absorption.

To investigate the pharmacokinetics of clarithromycin citrate salt and the effect of food on the absorption of free base and citrate salt, clarithromycin citrate was prepared and the in vitro intrinsic dissolution profiles of the free base and the salt were examined at pH 5.0 and pH 6.8. The pharmacokinetic profiles of clarithromycin following a single oral administration as the free base and its citrate salt (equivalent to 75 mg clarithromycin) were evaluated in eight beagle dogs. The plasma concentrations of clarithromycin were determined by reversed-phase liquid chromatography coupled to tandem mass with positive ion electrospray ionization using the multiple reaction monitoring method. The dissolution rates of clarithromycin and its citrate salt were similar at pH 5.0; however, at pH 6.8 citrate salt significantly enhanced the dissolution rate of clarithromycin. Clarithromycin's relative bioavailability value as expressed by the ratio of total mean area under the curve for clarithromycin citrate to that of clarithromycin was 104.2% and 110.1% under fast and fed conditions, respectively. The clarithromycin plasma area under the curve ratio was 33.4% and 25.7%, respectively, following oral clarithromycin or clarithromycin citrate salt drug coadministration with breakfast compared to fast-state controls (P < 0.05). There was no difference in pharmacokinetic parameters between clarithromycin and clarithromycin citrate salt under fast and fed conditions, but under the fed condition, T(max) was delayed and the C(max) of clarithromycin citrate salt and clarithromycin was decreased relative to the fasted condition, indicating that the consumption of this meal substantially reduced the drug's bioavailability.

Sleep Deprivation Induces Dry Eye Through Inhibition of PPARα Expression in Corneal Epithelium.

Purpose: To determine if sleep deprivation induces dry eye through altering peroxisome proliferator-activated receptor alpha (PPARα) expression in mice. Methods: The "stick over water" sleep deprivation-induced dry eye (SDE) model evaluated PPARα involvement in inducing this condition. Scanning electron microscopy (SEM) examined microvilli morphology in superficial corneal epithelial cells (SCECs) in SDE and PPARα-/- mice. Quantitative RT-PCR (qRT-PCR) and Western blot (WB) or immunostaining evaluated PPARα, carnitine palmitoyl transferase 1α (CPT1α), and transient receptor potential vanilloid 6 (TRPV6) expression levels and Ezrin phosphorylation status. Hematoxylin-eosin and Oil Red O staining characterized meibomian gland morphology and corneal lipid accumulation, respectively. Phenol red cotton threads measured tear production. In cultured corneal epithelial sheets, qRT-PCR, WB, and SEM determined the individual effects of fenofibrate and MK886 (PPARα agonist and antagonist, respectively) on PPARα, TRPV6 expression, and SCEC microvilli morphology. Results: Corneal epithelial lipid accumulation, microvilli morphologic changes, and decreased tear production were associated with marked declines in PPARα, CPT1α, and TRPV6 expression levels as well as Ezrin phosphorylation status, whereas meibomian glands were unaltered in SDE mice. These effects of SDE mice mimicked those in their nonstressed PPARα-/-counterpart. Topical application of fenofibrate reversed these effects in SDE corneas. In cultured corneal epithelial sheets, fenofibrate increased PPARα and TRPV6 gene and protein expression levels and restored microvilli morphology, whereas MK886 attenuated these changes. Conclusions: Sleep deprivation induces dry eye through abnormal SCEC microvilli morphology, which is caused by sequential downregulation of PPARα, TRPV6 expression, and Ezrin phosphorylation status in mice.

[The delivery mechanism of micro-porous osmotic pump tablets].

To investigate the delivery mechanism of micro-porous osmotic pump tablets ( MPOP), taking tramadol hydrochloride ( TR) as the model drug, tramadol hydrochloride micro-porous osmotic pump tablets (TR MPOP) were prepared with compressible starch as diluent, cellulose acetate as coating material, polyethylene glycol 400 as pore-forming agents. The equilibrium solubility and osmolality of TR were determined. The effects of fillers in tablet cores, coating levels, and osmotic pressures of release media on expansion behavior of preparations were described. The influences of the category, osmolality, and pH value of release media, release methods, and release conditions on release curves of tablets were evaluated. Based on several models, the delivery pattern of TR MPOP was fitted. The equilibrium solubility in water and osmolality of TR were (775.8 +/- 17.7) g x L(-1) and 4.036 Osmol x kg(-1), respectively. During the drug-release period, it was observed that the tablets expanded markedly in response to the expansion characteristics of compressible starch and the osmotic pressure difference across the membrane. When osmotic pressure of release media increased, the significant change of the equilibrium solubility of TR was not found, but the release rates of TR MPOP decreased significantly. The delivery rate was not influenced by the pH of release mediums, dissolution methods and paddle stirring rates. The drug release profile conformed to the model of zero order in 8 h. The pore-forming agents were dissolved in release medium, which caused micro-pores. The expansion of tablets made the size of micropores bigger, and then the drug-releasing pores were obtained. It was proved that the drivers of drug delivering from TR MPOP were mainly the difference of osmotic pressure, and secondly the difference of solubility. TR MPOP were the controlled-release preparation.

Investigation of microemulsion system for transdermal delivery of meloxicam.

A new oil-in-water microemulsion containing 0.375% meloxicam was developed in order to improve the skin permeability of meloxicam. Among various surfactants and cosurfactants investigated in the microemulsion system, polyoxyethylene sorbitan trioleate (Tween 85) showed excellent solubility and ethanol expressed skin permeation enhancing effect for meloxicam. The microemulsion existence ranges were defined through the construction of the pseudo-ternary phase diagram. The effect of the content of isopropyl myristate (IPM) and the effect of the mass ratio of the surfactant/cosurfactant (Km) on skin permeation of meloxicam were evaluated with excised rat skins. The optimum formulation with the highest skin permeation rate (5.40 microg/cm2/h) consisted of 0.375% meloxicam, 5% IPM, 50% Tween 85/ethanol (1:1) and water.

[Determination of salidroside and p-tyrosol in Hongjingtian for injection(freezing-dry) by SPE-HPLC].

OBJECTIVE: To assay salidroside and p-tyrosol in Hongjingtian for injection (freezing-dry). METHOD: Samples were purified by Sep-Pak C18 column and salidroside and p-tyrosol were determined by HPLC with Irregular-H C18 (4.6 mm x 250 mm, 5 microm), and eluted with a mobile phase of methanol-acenitonitrile -0.06% phosphate (10: 10:80). The flow rate was 1.0 mL x min(-1), the detection wavelength was set at 275 nm and the column temperature was maintained at 30 degrees C. RESULT: The calibration curves were linear in the range of 2.24-22.4 microg for salidroside (0.999 7) and 0.856-8.56 microg for p-tyrosol (0.999 6), the average recovery was 101.3%, 99.8% respectively. CONCLUSION: The method is convenient, rapid, accurate and reliable.

Evaluation of in-vitro dissolution and in-vivo absorption for two different film-coated pellets of clarithromycin.

The aim of this study was to compare two formulations of film-coated pellets containing clarithromycin after single oral dose study in healthy male volunteers. Two formulations with different coating polymers were prepared: formulation-1 (F-1) was prepared by incorporating three kinds of pH-dependent gradient-release coated pellets into capsules and formulation-2 (F-2) was prepared by coated with an insoluble semiosmotic film. Release profiles of film-coated pellets were evaluated using paddle method under different conditions. Pharmacokinetic profiles of these formulations were obtained in three healthy male volunteers and compared to commercially available immediate release (IR) tablets. The relative bioavailability based on the AUC0-24h was found to be 96.2% and 58.7% for F-1 and F-2 compared with IR, and the Tmax was delayed.

Thermosetting gels with modulated gelation temperature for ophthalmic use: the rheological and gamma scintigraphic studies.

For ophthalmic drug delivery, Pluronic F127 solutions have a phase transition temperature too low for them to be instilled into the eye at room temperature. Refrigerator storage is usually required to make administration easier, whereas the potential irritation of cold to the sensitive ocular tissues may result in poor topical bioavailability. The purpose of this study is to develop a thermosetting gel with a suitable phase transition temperature by combining Pluronic analogs and to examine the influence of incorporating mucoadhesive polysaccharide, sodium hyaluronate (HA-Na), on the ocular retention of the gel. Dynamic rheological method and single photon emission computing tomography (SPECT) technique were used to ex/in vivo evaluate the thermosetting gels, respectively. An optimized formulation containing 21% F127 and 10% F68 increased the phase transition temperature by 9 degrees C as evaluated by elasticity modulus compared to that of individual 21% F127 solution. Rheological behaviors of the Pluronic solutions showed that the combined Pluronic formulation was free flowing liquid below 25 degrees C and converted to a firm gel under the physiological condition. Furthermore, this formulation possessed the highest viscosity both before and after tear dilution at 35 degrees C. Gamma scintigraphic data demonstrated that the clearance of the thermosetting gel labeled with 99mTc-DTPA was significantly delayed with respect to the phosphate buffered solution, and at least a threefold increase of the corneal residence time was achieved. However, no further improvement in the ocular retention was observed when adding HA-Na into the thermosetting gel due to the substantially decreased gel strength.