Solubility-modulated monolithic osmotic pump tablet for atenolol delivery.

A method for the preparation of monolithic osmotic pump tablet was obtained by modulating atenolol solubility with acid. Tartaric acid was used as solubility promoter, sodium chloride as osmotic agent and polyvinyl pyrrolidone as retardant agent. Ethyl cellulose was employed as semipermeable membrane containing polyethylene glycol 400 as plasticizer. The formulation of atenolol monolithic osmotic pump tablet was optimized by orthogonal design and evaluated by similarity factor (f(2)). The optimal monolithic osmotic pump tablet was found to be able to deliver atenolol at the rate of approximate zero-order up to 24h, independent of release media and agitation rate. The approach of solubility-modulated by acid-alkali reaction might be used for the preparation of osmotic pump tablet of other poorly water-soluble drugs with alkaline or acid groups.     

Delivery of prazosin hydrochloride from osmotic pump system prepared by coating the core tablet with an indentation

The preparation of an osmotic pump tablet was simplified by elimination of laser drilling using prazosin hydrochloride as the model drug. The osmotic pump system was obtained by coating the indented core tablet compressed by the punch with a needle. A multiple regression equation was achieved with the experimental data of core tablet formulations, and then the formulation was optimized. The influences of the indentation size of the core tablet, environmental media, and agitation rate on drug release profile were investigated. The optimal osmotic pump tablet was found to deliver prazosin hydrochloride at an approximately constant rate up to 24 hr, and independent on both release media and agitation rate. Indentation size of core tablet hardly affected drug release in the range of 0.80-1.15 mm. The method that is simplified by elimination of laser drilling may be promising for preparation of an osmotic pump tablet.     

Delivery of Prazosin Hydrochloride from Osmotic Pump System Prepared by Coating the Core Tablet with an Indentation

The preparation of an osmotic pump tablet was simplified by elimination of laser drilling using prazosin hydrochloride as the model drug. The osmotic pump system was obtained by coating the indented core tablet compressed by the punch with a needle. A multiple regression equation was achieved with the experimental data of core tablet formulations, and then the formulation was optimized. The influences of the indentation size of the core tablet, environmental media, and agitation rate on drug release profile were investigated. The optimal osmotic pump tablet was found to deliver prazosin hydrochloride at an approximately constant rate up to 24 hr, and independent on both release media and agitation rate. Indentation size of core tablet hardly affected drug release in the range of 0.80–1.15 mm. The method that is simplified by elimination of laser drilling may be promising for preparation of an osmotic pump tablet.     

Preparation of bilayer-core osmotic pump tablet by coating the indented core tablet

In this paper, a bilayer-core osmotic pump tablet (OPT) which does not require laser drilling to form the drug delivery orifice is described. The bilayer-core consisted of two layers: (a) push layer and (b) drug layer, and was made with a modified upper tablet punch, which produced an indentation at the center of the drug layer surface. The indented tablets were coated by using a conventional pan-coating process. Although the bottom of the indentation could be coated, the side face of the indentation was scarcely sprayed by the coating solution and this part of the tablet remained at least partly uncoated leaving an aperture from which drug release could occur. Nifedipine was selected as the model drug. Sodium chloride was used as osmotic agent, polyvinylpyrrolidone as suspending agent and croscarmellose sodium as expanding agent. The indented core tablet was coated by ethyl cellulose as semipermeable membrane containing polyethylene glycol 400 for controlling the membrane permeability. The formulation of core tablet was optimized by orthogonal design and the release profiles of various formulations were evaluated by similarity factor (f(2)). It was found that the optimal OPT was able to deliver nifedipine at an approximate zero-order up to 24 h, independent on both release media and agitation rates. The preparation of bilayer-core OPT was simplified by coating the indented core tablet, by which sophisticated technology of the drug layer identification and laser drilling could be eliminated. It might be promising in the field of preparation of bilayer-core OPT.     

阿替洛尔单层芯渗透泵片的制备

目的以阿替洛尔为模型药物研究单层芯渗透泵片简化的制备方法，并进行处方优化。方法用自行设计的带针冲头压制带孔单层片芯， 以乙基纤维素为膜材包衣制备渗透泵片， 采用相似因子为指标筛选处方。结果 单层芯渗透泵片的片芯处方、包衣膜组成及厚度是影响释药的主要因素。在1.00～1.14 mm，片芯孔径对释药影响不大。结论本制备方法可免去激光打孔过程，制得的阿替洛尔单层芯渗透泵片能24 h匀速释药。     

Preparation of monolithic osmotic tablet of quercetin loaded by solid dispersion

The objective of this study was to prepare monolithic osmotic tablet of quercetin for controlled drug release. Quercetin-PVP solid dispersion was prepared to enhance its solubility and dissolution rate. Solid dispersion, suspending agents, osmotic agents and other conventional excipients were used as tablet core composition and cellulose acetate (CA) with plasticizer as release controlling membrane. Different formulation variables, the amounts of PEO (polyethylene oxide), NaCl, plasticizer, and coating weight gain were optimized to gain the optimum formulation. The mechanism of drug release from monolithic osmotic tablet was also discussed. The optimal monolithic osmotic pump tablet could deliver quercetin at the rate of approximate zero-order up to 12 h, and the cumulative release was 90.74%. The developed monolithic osmotic system for quercetin loaded by solid dispersion was found to be a promising approach for controlled release of poorly-water soluble drug candidates.     

Design and evaluation of osmotic pump-based controlled release system of Ambroxol Hydrochloride

The purpose of the present study was to design and evaluate an osmotic pump-based drug delivery system for controlling the release of Ambroxol Hydrochloride (Amb). Citric acid, lactose and polyethylene glycol 6000 (PEG 6000) were employed as osmotic agents. Surelease EC containing polyethylene glycol 400 (PEG 400) controlling the membrane porosity was used as semi-permeable membrane. The formulation of tablet core was optimized by orthogonal design and evaluated by weighted mark method. The influences of the amount of PEG 400 and membrane thickness on Amb release were investigated. The optimal osmotic pump tablet (OPT) was evaluated in different release media and at different stirring rates. The major release power confirmed was osmotic pressure. The release of Amb from OPT was verified at a rate of approximately zero-order, and cumulative release percentage at 12?h was 92.6%. The relative bioavailability of Amb OPT in rabbits relative to the commercial sustained capsule was 109.6%. Our results showed that Amb OPT could be a practical preparation with a good prospect.     

Formulation and evaluation of extended release asymmetric membrane capsules of atenolol

The objective of this study was to demonstrate that the asymmetric membrane capsule can be used to deliver a poorly water soluble drug with a pH dependent solubility such as atenolol for extended periods of time by modulating solubility with organic acid. In osmotic systems, the release rate of an excipient relative to the release rate of the drug is an important factor that determines the duration of drug release. Consequently, for maintaining the desired pH over the entire period of drug dissolution a suitable thickening and suspending agent can be incorporated. By optimizing the concentration of thickening agent, it is possible to extend the availability of pH modifier in the core to provide an osmotic driving force or solubilization over the entire delivery period, so that the desired profile can be achieved for an active agent that has lower solubility characteristics. Finally, it was observed that the release rate of atenolol was influenced by the concentration of citric acid, mannitol and hydroxypropyl methylcellulose (HPMC). Results of scanning electron microscopy studies showed the formation of pores in the membrane from where the drug release occurred. The optimal formulation was found to be able to deliver atenolol at the rate of approximate zero-order up to 24 h, independent of pH of release media and agitation rate.     

夹芯渗透泵片用于水不溶性药物的控制释放夹芯渗透泵片用于水不溶性药物的控制释放

目的研究夹芯渗透泵片用于水不溶性药物的24 h控制释放。方法以硝苯吡啶为模型药物,制备夹芯渗透泵片,研究处方、释药孔径等因素对夹芯渗透泵片释药规律的影响,并考察包衣的机械性质。结果药物层中聚氧乙烯和膨胀层中氯化钾对释药的正面影响最大。在0.50～1.40 mm,孔径对释药影响不大。醋酸纤维素包衣牢固可靠,能承受0.34～2.85 MPa的内压。结论夹芯渗透泵片能24 h匀速释放水不溶性药物。环境介质和搅拌对释药的影响不大。与市售双层渗透泵片相比,夹芯渗透泵片免去了打孔前的药物层辨认过程,制备过程简化。     

法莫替丁单室单层渗透泵片的制备

目的:以法莫替丁(famotidine,FMT)为模型药物研究难溶性药物单层渗透泵片的制备。方法:以PEO,HPMC,NaCl和柠檬酸组成片芯,以醋酸纤维素为包衣材料制备FMT单层渗透泵片,并对片芯组成优化;用相似因子法考察了体外释放条件。结果:片芯最佳组成为:FMT40 mg,PEON1065 mg,HPMCK4M70 mg,NaCl 50 mg,柠檬酸20 mg。释放介质和转速对药物释放无显著影响。本渗透泵片24 h恒速释药,累积释药率93%。结论:本渗透泵片制备简便,能较好地控制FMT24 h匀速释药。     

Novel osmotic pump tablet using core of drug-resin complexes for time-controlled delivery system

A novel elementary osmotic pump tablet was developed. The system uses the core of drug-resin complexes (DRCs) loaded with propranolol hydrochloride (PNH) for time-controlled delivery. In traditional osmotic pump tablets (OPTs), the lag time was always minimized. However, in the DRCs osmotic pump tablet (DRCOPT), the lag time was increased to achieve the time-controlled delivery. The quantity of osmotic agent in the core and channeling agent in the coating solution as well as weight gain were confirmed to be essential for the release behavior. A spherical symmetric design was applied to the optimization of the DRCOPT. The optimal formulation mainly consisted of DRC 100 mg, polyethyleneoxide (N80) 182 mg, and NaCl 30 mg. The ratio of cellulose acetate (CA)/polyethylene glycol 4000 was 15:3 (w/w) in coating solution, and the weight gain was 8%. The release behavior of the optimal DRCOPT was evaluated in media with different pH, rotation speeds, and ionic strength. It was found to generate a 2-h lag time, to deliver PNH at a rate of zero order from 2 h to 14 h in the medium of NaCl 0.15 mol/l, and the cumulative release at 24 h was 94%. Drug relee was independent of pH and rotation speed, but was proportional to ionic strength. In summary, the lag time could be used in therapeutic regimens with the characteristics of chronotherapy because of the lag time and provides a new concept for the development of osmotic pumps.     

磷酸川芎嗪微孔渗透泵片的研制及释药机制研究

目的:制备磷酸川芎嗪微孔渗透泵片,并进行处方优化和释药机制考察。方法:利用单因素考察和正交试验设计,优化筛选出最佳处方;测定不同处方制剂累积释药百分率;并对其释药机制进行探讨。结果:包衣膜中致孔剂聚乙二醇400用量、片芯羟丙甲基纤维素含量、增塑剂邻苯二甲酸二丁酯用量、包衣增重为影响药物释放的4个重要因素。最优处方为聚乙二醇400用量10%,羟丙甲基纤维素用量5%,增塑剂10%,包衣增重12mg,制得微孔渗透泵片在12h内呈现零级控释释放特征(r=0.99981),累积释放率为94.2%,批间重现性良好,不受胃肠道环境影响;释药机制包括渗透泵机制和扩散机制,以渗透泵机制为主。结论:该微孔渗透泵片处方及制备工艺简单有效,12h零级释放特征显著,重现性好,可为工业生产提供理论依据。     

Push-pull osmotic pump for zero order delivery of lithium carbonate: development and in vitro characterization

Lithium carbonate, a drug with narrow therapeutic index, needs therapeutic drug monitoring and dose adjustment to maintain lithium level within the therapeutic window. Conventional formulations of lithium carbonate exhibit immediate drug release causing swing/fluctuations in the plasma concentration of lithium, consequently leading to unfavorable side-effects and make dose adjustment difficult. The push-pull osmotic pump has been developed for zero order delivery of lithium carbonate for a period of 24 h. The effect of various formulation variables on bilayer core tablet and its semi permeable coating along with orifice diameter have been investigated and optimized for desired drug release profile. Drug release was found to be inversely proportional to the membrane thickness but directly related to the amount of pore formers in the semipermeable membrane. Images from a scanning electron microscope confirmed the presence of pores in the semipermeable membrane which facilitated the required water penetration. No distortion or change in orifice shape was noticed prior to and after the dissolution study. Drug release from the developed formulation was found to be independent of pH, agitation intensity and agitation mode but depended on osmotic pressure of dissolution media.     

硝苯地平双层控释片的制备与体外释放

目的:采用渗透泵技术,制备硝苯地平控释片,并进行体外释放研究。方法:采用单因素筛选处方,分别考察含药层高分子聚氧乙烯(PEO)相对分子质量、含药层渗透压活性物质、助推层中高分子PEO相对分子质量、助推层的含量、压力、包衣膜厚度和释药孔孔径等因素对释放度的影响。结果:通过系列研究,结果表明,衣膜的完整性、能否释放药物以及释药速度的快慢主要受含药层中高分子PEO的相对分子质量、渗透压活性物质和助推层中高分子PEO相对分子质量、含药层和助推层体积比及压力、孔径、半透膜等因素的影响。结论:自制的硝苯地平双层渗透泵控释片在体外释药条件下释药稳定,在3～14h内零级特征明显(r=0.9995)、平均释药量约为8%/h、衣膜完整。     

吲达帕胺微孔渗透泵片的设计与制备

目的 设计并制备吲达帕胺微孔渗透泵片剂.方法通过单因素考察和正交试验设计,以释放度为指标筛选优化处方.结果 以微晶纤维素(MCC)、可压性淀粉、乳糖、氯化钠、羟丙基甲基纤维素(HPMC) K4M、十二烷基硫酸钠为片芯材料;以醋酸纤维素、聚乙二醇(PEG) 400、邻苯二甲酸二乙酯(DEP)的丙酮溶液为包衣液,制备了...     

乌拉地尔渗透泵片的制备

目的:制备体外24h恒速释药的乌拉地尔渗透泵片。方法:以氯化钠和高、低分子量(4×106、2×105)的聚氧化乙烯(PEO)组成片芯,醋酸纤维素和聚乙二醇400为包衣液,制备乌拉地尔渗透泵片;采用相似因子(f2)为指标筛选片芯处方,并考察了其释药机制。结果:与理想释药曲线最接近的片芯处方组成为乌拉地尔60mg,氯化钠190mg,PEO(Mr4×106)90mg,PEO(Mr2×105)90mg,药物24h维持零级释放。结论:本渗透泵片制备方法简便,且零级释药特征明显。     

Mechanistic Investigation of Drug Release from Asymmetric Membrane Tablets: Effect of Media Gradients (Osmotic Pressure and Concentration), and Potential Coating Failures on <Emphasis Type="BoldItalic">In Vitro</Emphasis> Release

Purpose An asymmetric membrane (AM) tablet was developed for a soluble model compound to study the in vitro drug release mechanisms in challenge conditions, including osmotic gradients, concentration gradients, and under potential coating failure modes. Porous, semipermable membrane integrity may be compromised by a high fat meal or by the presence of a defect in the coating that could cause a safety concern about dose-dumping. Methods The osmotic and diffusional release mechanisms of the AM tablet were independently shut down such that their individual contribution to the overall drug release was measured. Shut off of osmotic and diffusional release was accomplished by performing dissolution studies into receptor solutions with osmotic pressure above the internal core osmotic pressure and into receptor solutions saturated with drug, respectively. The effect of coating failure modes on in vitro drug release from the AM tablet was assessed through a simulated high-fat meal and by intentionally compromising the coating integrity. Results The predominant drug release mechanism for the AM tablet was osmotic and accounted for approximately 90–95% of the total release. Osmotic release was shutoff when the receptor media osmotic pressure exceeded 76 atm. Diffusional release of the soluble drug amounted to 5–10% of the total release mechanism. The observed negative in vitro food effect was attributed to the increased osmotic pressure from the high fat meal when compared to the predicted release rates in sucrose media with the same osmotic pressure. This suppression in drug release rate due to a high fat meal is not anticipated to affect in vivo performance of the dosage form, as the rise in pressure is short-lived. Conclusions Drug release from the AM system studied was determined to be robust to varying and extreme challenge conditions. The conditions investigated included varying pH, agitation rate, media osmotic pressure, media saturated with drug to eliminate the concentration gradient, simulated high fat meal, and intentionally placed film coating defects. Osmotic and diffusional shut off experiments suggest that the mechanism governing drug release is a combination of osmotic and diffusional at approximately 90–95% and 5–10%, respectively. In addition, the coating failure mode studies revealed this formulation and design is not significantly affected by a high fat meal or by an intentionally placed defect in the film coating, and more specifically, did not result in a burst of drug release.     

包衣处方对盐酸文拉法辛微孔渗透泵型控释片体外释药的影响

目的考察包衣处方对盐酸文拉法辛口服微孔渗透泵控释片体外释药的影响,并优选最佳包衣处方。方法考察聚乙二醇400(PEG400)的用量、包衣增量、邻苯二甲酸二丁酯(DBP)的种类和用量4个因素对释放的影响,并通过正交设计优化包衣处方。结果盐酸文拉法辛微孔渗透泵控释片的体外释药符合零级释放规律,释药速率受致孔剂、增塑剂、衣膜厚度的影响均较大。结论通过对包衣处方的优化,盐酸文拉法辛口服微孔渗透泵控释片能够恒速释药。     

度米芬渗透泵片的研制

目的:制备度米芬渗透泵片,并考察、分析其释药机制。方法:以均匀设计法优化包衣工艺,测定不同处方制剂累积释药百分率,研究渗透泵片的制剂学特征及释药机制。结果:致孔剂聚乙二醇-400用量和包衣膜厚度对药物释放均有影响。优化包衣工艺条件为聚乙二醇-400用量12%、包衣膜厚度10mg。喷雾速度、温度、转速对释药行为无影响。结论:改变度米芬渗透泵片包衣成分的组成,制剂可持续12h释药;该制剂释药机理包括扩散和渗透泵原理。     

Monolithic Osmotic Tablets for Controlled Delivery of Antihypertensive Drug

An oral monolithic osmotically controlled delivery system for nifedipine using asymmetric membrane technology was developed and evaluated. Unlike conventional osmotic systems, which require laser drilling, this system releases the drug in a controlled manner from asymmetric membrane coated core tablets. Asymmetric membrane is formed by dry process with phase inversion technology process using cellulose acetate as the coating material. Higher water influx of this membrane aids in delivery of nifedipine, which is highly water insoluble with low osmotic pressure. The porous structure of the membrane was confirmed by scanning electron microscopy. Influence of different osmotic agents on drug release was evaluated. In vitro release studies showed that as concentration of osmotic agents was increased, the drug release was also enhanced. Drug release from the developed monolithic system was independent of external agitation and pH of dissolution media. Comparative in vitro release data was obtained using different types of coating membranes like controlled porosity membrane and dense coating membrane with mechanically drilled orifice. Osmotic pressure generated in the system was determined using freezing point osmometer. The osmotic pressure developed was found to be linearly proportional to time and concentration of osmotic agent.