In Vitro and In Vivo Evaluation of Two Extended Release Preparations of Combination Metformin and Glipizide

A system that can deliver multi-drugs at a prolonged rate is very important to the treatment of various chronic diseases such as diabetes, asthma, and heart disease. Two controlled-release systems, which exhibited similar release profiles of metformin and glipizide, i.e., elementary osmotic pump tablets (EOP) and bilayer hydrophilic matrix tablet (BT), were designed. The effects of pH and hydrodynamic conditions on drug release from two formulations were investigated. It was found that both drug releases from EOP were not sensitive to dissolution media pH and hydrodynamics change, while the release of glipizide from BT was influenced by the stirring rate. Moreover, in vivo evaluation was performed, relative to the equivalent dose of conventional metformin tablet and glipizide tablet, by a three-crossover study in six Beagle dogs. Cumulative percent input in vivo was compared to in vitro release profiles. The linear correlations of metformin and glipizide between fraction absorbed in vivo and fraction dissolved in vitro were established for EOP—a true zero-order release formula, whereas only nonlinear correlations were obtained for BT. In conclusion, drug release from EOP was both independent of in vitro and in vivo conditions, where the best sustained release effect was achieved, whereas the in vitro dissolution test employed for BT needed to be further optimized to be biorelevant.     

Possible Mechanism for Drug Retardation from Glyceryl Monostearate Matrix System

Lipophilicity was evaluated as a possible mechanism for drug retardation from a glyceryl monostearate matrix system. Lipophilicity of the glyceryl monostearate matrix system was studied using contact angle measurement of water droplets on the surface of compressed disks, extrudate ascension of water, and movement of water through a powder mixture packed in a high-performance liquid chromatographic (HPLC) column. Increase in glyceryl monostearate content resulted in an increase in water droplet contact angle, decrease in the rate of water ascending the extrudate, and increase in the pressure values as a function of flow rate of water moving through the powder mixture. These could be due to the increase in lipophilicity of the matrix, rendering the matrix less wettable. As a result, the rate of water penetration into the matrix decreased, and the drug release could be sustained.     

高效液相色谱法测定吡磺环已脲血药浓度的改进

本文就HPLC法测定吡磺环已脲的血药浓度进行了改进。色谱柱为ODS C_(18)柱,流动相为乙腈—甲醇—水(30:25:45)的混合溶液,pH3.5。甲醇沉淀血浆中蛋白,离心后取上清液直接进样,检测波长275nm。回收率大于95％,RSD小于10％,血浆中最低检测浓度10ng/ml,在0.02～1.00μg/mi浓度范围内,r=0.9996。方法简便、快速、灵敏度高,可推广应用。     

In vitro and in vivo evaluation of two extended release preparations of combination metformin and glipizide

A system that can deliver multi-drugs at a prolonged rate is very important to the treatment of various chronic diseases such as diabetes, asthma, and heart disease. Two controlled-release systems, which exhibited similar release profiles of metformin and glipizide, i.e., elementary osmotic pump tablets (EOP) and bilayer hydrophilic matrix tablet (BT), were designed. The effects of pH and hydrodynamic conditions on drug release from two formulations were investigated. It was found that both drug releases from EOP were not sensitive to dissolution media pH and hydrodynamics change, while the release of glipizide from BT was influenced by the stirring rate. Moreover, in vivo evaluation was performed, relative to the equivalent dose of conventional metformin tablet and glipizide tablet, by a three-crossover study in six Beagle dogs. Cumulative percent input in vivo was compared to in vitro release profiles. The linear correlations of metformin and glipizide between fraction absorbed in vivo and fraction dissolved in vitro were established for EOP—a true zero-order release formula, whereas only nonlinear correlations were obtained for BT. In conclusion, drug release from EOP was both independent of in vitro and in vivo conditions, where the best sustained release effect was achieved, whereas the in vitro dissolution test employed for BT needed to be further optimized to be biorelevant.     

Cyclodextrin complex osmotic tablet for glipizide delivery

Poorly soluble glipizide was selected as the model drug to prepare osmotic pump tablets (OPT) with proper accessorial material after it was made an inclusion complex by kneading method in order to increase solubility. Polyethylene glycol 4000 (PEG4000) and cellulose acetate (CA) were selected as the coating materials, and acetone-water (95:5) co-solvent was employed as the coating medium. The effects of the osmotic promoting agent, diameter of the drug-releasing orifice, coating composition, and coat weight on the drug release profile were investigated. The drug release profile of the optimal formulation was compared with a commercialized push-pull osmotic tablet. The results indicated that glipizide-cyclodextrin inclusion complex OPT had excellent zero-order release characteristics in vitro.     

Cyclodextrin Complex Osmotic Tablet for Glipizide Delivery

ABSTRACT

Poorly soluble glipizide was selected as the model drug to prepare osmotic pump tablets (OPT) with proper accessorial material after it was made an inclusion complex by kneading method in order to increase solubility. Polyethylene glycol 4000 (PEG4000) and cellulose acetate (CA) were selected as the coating materials, and acetone–water (95:5) co-solvent was employed as the coating medium. The effects of the osmotic promoting agent, diameter of the drug-releasing orifice, coating composition, and coat weight on the drug release profile were investigated. The drug release profile of the optimal formulation was compared with a commercialized push–pull osmotic tablet. The results indicated that glipizide–cyclodextrin inclusion complex OPT had excellent zero-order release characteristics in vitro.     

Spectral Data Analyses and Structure Elucidation of Hypoglycemic Drug Glipizide

Abstract

The infrared spectrum, ultraviolet spectrum, mass spectrum, and nuclear magnetic resonance spectrum of glipizide, a blood-glucose-lowering drug, were reported and interpreted comprehensively. All the ¹H and ¹³C NMR chemical shifts were assigned by means of distoritionless enhancement by polarization transfer-135, ¹H-¹H and ¹³C-¹H correlation spectroscopy, and correlation spectroscopy via long range coupling. The main characteristic fragmentations, in electron impact and electrospray ionization mass spectra, vibrations of functional groups in infrared spectrum, and electron transition in ultraviolet spectrum of glipizide were also discussed in detail.     

In vitro and in vivo studies on the complexes of glipizide with water-soluble β-cyclodextrin–epichlorohydrin polymers

The purpose of this study was to evaluate the potential of a newly modified cyclodextrin derivative, water-soluble β-cyclodextrin–epichlorohydrin polymer (β-CDP), as an effective drug carrier to enhance the dissolution rate and oral bioavailability of glipizide as a poorly water-soluble model drug. Inclusion complexes of glipizide with β-CDP were prepared by the co-evaporation method and characterized by phase solubility, dissolution, and differential scanning calorimetry. The solubility curve was classified as type A_L, which indicated the formation of 1:1 complex between glipizide and β-CDP. β-CDP had better properties of increasing the aqueous solubility of glipizide compared with HP-β-CD. The dissolution rate of drug from the β-CDP complexes was significantly greater than that of the corresponding physical mixtures indicating that the formation of amorphous complex increased the solubility of glipizide. Moreover, the increment in drug dissolution rate from the glipizide/β-CDP systems was higher than that from the corresponding ones with HP-β-CD, which indicated that β-CDP could provide greater capability of solubilization for poorly soluble drugs. Furthermore, in vivo study revealed that the bioavailability of glipizide was significantly improved by glipizide /β-CDP inclusion complex after oral administration to beagle dogs.     

罗红霉素对家兔体内格列吡嗪药动学的影响

目的: 研究罗红霉素在健康和糖尿病家兔体内对格列吡嗪胶囊代谢的影响。方法: 健康对照组家兔和糖尿病组家兔各5只,每只口服格列吡嗪 5 mg。经2周清洗期后,每只家兔口服罗红霉素 50.0 mg,每天2次,持续3天,第4天口服相同剂量格列吡嗪。所有家兔均在给予格列吡嗪前及给药后 0.5、1.5、3、5、7、9、11、24、35 h,经耳缘静脉采血,用HPLC法测定各时间点格列吡嗪的血药浓度,测得的血药浓度结果用药动学软件DAS2.0 进行曲线拟合,采用自身对照法分析给予罗红霉素前后格列吡嗪药动学的变化。结果: 格列吡嗪在家兔体内的药动学符合单室模型,健康对照组家兔单用格列吡嗪,其t_1/2、C_max、AUC分别为(2.9±0.4) h,(5815±940) μg/L,(58919±860) μg·h·L^-1;加用罗红霉素后其t_1/2、C_max、AUC分别为(3.5±0.9) h,(6165±764),(76515±1830) μg·h·L^-1。糖尿病组家兔单用格列吡嗪,其t_1/2、C_max、AUC分别为(1.7±0.4) h,(4307±580)μg/L,(32469±786) μg·h·L^-1;加用罗红霉素后其t_1/2、C_max、AUC分别为(3.2±1.5) h,(8531±1479) μg/L,(76489±1588) μg·h·L^-1 。给予罗红霉素前后格列吡嗪的t_1/2、C_max、AUC差异均存有统计学意义(P<0.05)。结论: 罗红霉素对家兔体内格列吡嗪的药动学有明显的影响,临床合用两药时需要注意调整剂量以防发生低血糖危害。     

液相色谱串联质谱法测定人血清中匹多莫德的浓度

目的: 建立液相色谱串联质谱法测定人血清中匹多莫德的浓度。方法: 血清样品用甲醇沉淀蛋白,内标为格列吡嗪,色谱柱为Lichrospher C₁₈ (4.6 mm×150 mm,5 μm),柱温为 30 ℃,流动相为甲醇-2.5 mmol/L NH₄Ac(90∶10,V/V),流速为 0.5 mL/min。质谱采用ESI离子源负离子检测,定量分析的离子对为:m/z 242.9/153.0(匹多莫德),m/z 444.0/169.9(内标格列吡嗪)。结果: 匹多莫德在 0.1~10 mg/L 范围内线性关系良好(r=0.9995),批内批间RSD均小于15%,提取回收率为 85.52%~98.30%。结论: 该方法快速,灵敏,准确,可用于匹多莫德的临床药动学研究。