Preparation of enteric coated timed-release press-coated tablets and evaluation of their function by in vitro and in vivo tests for colon targeting

As a new oral drug delivery system for colon targeting, enteric coated timed-release press-coated tablets (ETP tablets) were developed by coating enteric polymer on timed-release press-coated tablets composed of an outer shell of hydroxypropylcellulose and core tablet containing diltiazem hydrochloride (DIL) as a model drug. The results of the in vitro dissolution tests in JP 1st fluid (pH 1.2) and JP 2nd fluid (pH 6.8) indicated that these tablets showed both acid resistance and timed-release. To clarify whether ETP tablets could have been of use in the gastrointestinal tract, ETP tablets with a layer of phenylpropanolamine hydrochloride (PPA) (a marker of gastric emptying) between the enteric coating layer and outer shell were prepared, and were administered to beagle dogs. The gastric emptying time and lag time after gastric emptying were evaluated by determining the times at which PPA and DIL first appeared in the plasma (TFA(PPA) and TFA(DIL), respectively). TFA(PPA) and TFA(DIL) were about 4 and 7 h, respectively. This value of TFA(PPA) indicated that ETP tablets displayed acid resistance in the stomach as well as in JP Ist fluid. Subtraction of TFA(PPA) from TFA(DIL) gave a value of about 3 h which agreed well with the lag time determined by in vitro dissolution test in JP 2nd fluid. Also, the results seemed to be in accordance with the time at which the tablets reached the colon after gastric emptying. Therefore, ETP tablets seemed to be an effective tool for oral site-specific delivery including targeting of the colon.     

In-vitro/in-vivo correlation of pulsatile drug release from press-coated tablet formulations: a pharmacoscintigraphic study in the beagle dog.

The aim of the current study was to investigate the in-vitro and in-vivo performance of a press-coated tablet (PCT) intended for time delayed drug release, consisting of a rapidly disintegrating theophylline core tablet, press-coated with barrier granules containing glyceryl behenate (GB) and low-substituted hydroxypropylcellulose (L-HPC). The PCTs showed pulsatile release with a lag time dependent upon the GB and L-HPC composition of the barrier layer. In-vivo gamma-scintigraphic studies were carried out for PCTs containing GB:L-HPC at 65:35 w/w and 75:25 w/w in the barrier layer in four beagle dogs, in either the fed or fasted state. The in-vivo lag time in both the fed and fasted states did not differ significantly (p>0.05) from the in-vitro lag time. Additionally, no significant difference (p<0.05) between in-vivo fed and fasted disintegration times was observed, demonstrating that in-vivo performance of the PCT was not influenced by the presence or absence of food in the gastrointestinal tract. A distinct lag time was obtained prior to the appearance of drug in plasma and correlated (R2=0.98) with disintegration time observed from scintigraphic images. However, following disintegration, no difference in pharmacokinetic parameters (AUC(0-6 dis), K(el), Cmax) was observed. The current study highlighted the potential use of these formulations for chronopharmaceutical drug delivery.     

Dosage form design and in vitro/in vivo evaluation of cevimeline extended-release tablet formulations

The objective of the present work is to develop an extended-release dosage form of cevimeline. Two types of extended-release tablets (simple matrix tablets and press-coated tablets) were prepared and their potential as extended-release dosage forms were assessed. Simple matrix tablets have a large amount of hydroxypropylcellulose as a rate-controlling polymer and the matrix is homogeneous throughout the tablet. The press-coated tablets consisted of a matrix core tablet, which was completely surrounded by an outer shell containing a large amount of hydroxypropylcellulose. The simple matrix tablets could not sustain the release of cevimeline effectively. In contrast, the press-coated tablets showed a slower dissolution rate compared with simple matrix tablets and the release curve was nearly linear. The dissolution of cevimeline from the press-coated tablets was not markedly affected by the pH of the dissolution medium or by a paddle rotating speed over the range of 50–200 rpm. Furthermore, cevimeline was constantly released from the press-coated tablets in the gastrointestinal tract and the steady-state plasma drug levels were maintained in beagle dogs. These results suggested that the designed PC tablets have a potential for extended-release dosage forms.     

小儿清热止咳分散片的填充剂与崩解剂筛选

目的为了制备中药分散片,以小儿清热止咳糖浆方剂为模型药物筛选中药分散片的填充剂和崩解剂。方法以抗张强度、吸湿性和压缩功作为选择填充剂的依据,以吸水性实验、溶胀度实验、空白片崩解时限和加入质量分数为50%浸膏的片剂崩解时限为选择崩解剂的依据。测定发泡量和产气量作为选择泡腾崩解剂的依据。结果综合以抗张强度、吸湿性和压缩功大小,选择乳糖作为分散片的填充剂。溶胀性能优劣顺序是:CMS-Na>L-HPC(信越)>PVPP>MCC101>MCC301>L-HPC(国产)>MCC302>MCC102>滑石粉>干淀粉;吸水性能优劣顺序是:L-HPC(信越)>L-HPC(国产)>CMS-Na>PVPP>MCC302>MCC102>MCC301>MCC101>浸膏;单独使用微晶纤维素或超级崩解剂达不到分散片的质量要求,联用微晶纤维素和超级崩解剂,可以达到分散片质量要求。结论中药分散片的崩解剂可以采用超级崩解剂和微晶纤维素的混合物,泡腾崩解剂选用酒石酸和碳酸氢钠,其摩尔比为1.0∶0.8。     

Design and evaluation of microwave-treated orally disintegrating tablets containing polymeric disintegrant and mannitol

Microwave (MW) treatment was used to develop a formulation process for the preparation of wet molded orally disintegrating tablets (ODTs) consisting of mannitol and polymeric disintegrant with improved hardness and disintegration properties. The wet molded tablets were prepared in accordance with the conventional methods and subsequently heated by MW irradiation to induce the swelling of the tablet. Croscarmellose sodium, crospovidone, and low-substituted hydroxypropylcellulose (L-HPC) were evaluated for their use with this technology. NBD-020, which is a grade of L-HPC, provided the better hardness and disintegration results. In addition, the crystalline forms of mannitol impacted on hardness and disintegration properties of the ODT upon MW irradiation. The effects of the disintegrant ratio, δ and β crystalline mannitol ratio, amount of water, and compression force on the ODT properties were evaluated using the design of experiment method. MW-induced swelling was enhanced by an increase in the disintegrant ratio. Although the hardness of the tablet increased following MW treatment, the disintegration time became less than that of the MW-untreated tablets as the β-mannitol ratios increased. Taken together, the results indicated that the polymeric disintegrant greatly improved the properties of the molded tablets in combination with MW treatment.     

红景天口腔崩解片的制备及质量控制

目的:研究红景天口腔崩解片的制备工艺,并评价其质量。方法:用直接压片法制备口腔崩解片,以崩解时限、口感等为指标采用正交设计法对崩解片中崩解剂含量、矫味剂比例进行筛选并进行处方优化;高效液相色谱法(HPLC)测定红景天苷的含量。结果:成功制备红景天口腔崩解片;根据崩解时限选用的崩解剂方案为2%低取代羟丙基纤维素(L-HPC)、10%羧甲基淀粉钠(CMS-Na)、10%交联聚维酮(PVPP);红景天与矫味剂阿斯帕坦、柠檬酸的最佳比例为41∶1∶1;口腔崩解片处方优化的结果为含35%微晶纤维素(MCC)、8%PVPP、0.5%微粉硅胶;口腔崩解片中红景天苷含量为(99.8±0.5)%。结论:红景天口腔崩解片崩解快、分布均匀、口感好、刺激小,有利于中药成分的快速溶出和方便患者服用。     

盐酸尼卡地平定时释放片研究

目的：以盐酸尼卡地平为模型药对定时释放片的体内外定时释放效果进行研究。方法：用干压包衣技术制备盐酸尼卡地平定时释放片。用时间参数t_0.1和t_0.8对各因素(PEG6000用量、乙基纤维素粘度、衣层厚度、片硬度等)对药物释放的影响进行评价。通过溶蚀试验确定药物释放机理。用HPLC法对5名志愿者进行了人体药代动力学研究。结果：在体外,药物在(6.5±0.3) h开始释放,在(8.0±0.3) h药物释放完全;在人体内,定时释放片和普通片的t_max分别为(8.3±0.4) h和(1.3±0.4) h,t_lag分别为(6.4±0.3) h和(0.4±0.04) h, 定时释放片的相对生物利用度为93.6%±8.8%。结论：盐酸尼卡地平定时释放片在体内外具有显著的定时释放作用。     

氨茶碱栓剂与片剂生物利用度的比较

本文研究了氨茶碱栓剂与片剂的药代动力学参数。经换算后,栓剂360mg与片剂200mg具有相等的血药水平,但栓剂起效慢,维持时间较片剂稍长,临床可根据需要选择使用。氨茶碱栓除对肛门稍有刺激和有排便感外,其他副反应较片剂为轻。     

Comparative bioavailability of a microcrystalline theophylline tablet and uncoated aminophylline tablets

Summary The bioavailability of a rapidly dissolving tablet of theophylline and three brands of standard aminophylline tablets was estimated in a four way cross-over study involving 8 healthy adult volunteers. The relative extent of bioavailability as assessed by the measurement of the total area under the plasma concentration time curves showed no difference between the products (P>0.05). Computed estimates of the rate of drug absorption were similar for all 4 products tested. The results indicate that the rapidly dissolving tablet offers no advantage in respect to rate and extent of absorption over conventional aminophylline tablets.     

Biopharmaceutical evaluation of a tablet dosage form made from ethyl cellulose encapsulated aspirin particles

Ethyl cellulose encapsulated aspirin particles, suitable for preparation of direct compression tablets were prepared by the solvent evaporation method. Ethyl acetate was used as a solvent for the polymer in combination with a saturated solution of aspirin as the dispersing medium to prevent partitioning and drug loss. This resulted in a high yield of free-flowing, non-aggregated particles. In vitro-in vivo evaluations of the experimental aspirin tablets (made by direct compression of ethyl cellulose encapsulated particles) and three different commercial aspirin products (a conventional tablet, a timed-release tablet, and a timed-release caplet) were undertaken. Comparison of the dissolution in acidic media at pH 1.2 showed different release profiles for these products. While the conventional tablet and the timed-release caplet showed the highest and the lowest rate of release, respectively; the timed-release tablet and the experimentally made tablet revealed an intermediate rate and very similar release profiles. The cumulative urinary excretion data collected in a complete crossover study, using five healthy subjects further indicated that the experimental tablet has an in vivo availability identical to that of the timed-release tablet.     

Evaluation of cellulose II powders as a potential multifunctional excipient in tablet formulations

The use of UICEL-A/102 and UICEL-XL, the cellulose II powders, as a multifunctional direct compression excipient in the design of tablets containing hydrochlorothiazide (HCTZ) or ibuprofen (IBU), the model low and high dose drugs, respectively, has been reported. Commercial Oretic and Advil tablets containing HCTZ and IBU, respectively, and tablets made using Avicel PH-102 - the most commonly and widely used commercial direct compression excipient, were used in the study for comparison purposes. Tablets were made by first blending drug with the excipient and then with stearic acid, a lubricant, in a V-blender, followed by compressing into a tablet on a hydraulic press using 105 MPa of compression pressure and a dwell time of 30 s. The crushing strengths of HCTZ tablets decreased in the order Avicel PH-102>UICEL-XL, UICEL-A/102>Oretic and of IBU tablets in the order Avicel PH-102 > or = UICEL-XL approximately UICEL-A/102>Advil. The friability values for all tablets were well below the maximum 1% USP tolerance limit. UICEL-A/102 and UICEL-XL tablets containing HCTZ disintegrated rapidly (<25 s). Oretic tablets disintegrated in about 60 s, while Avicel PH-102 tablets remained intact during 1 h test period. The IBU tablets made using UICEL-A/102 disintegrated the fastest, UICEL-XL and Advil tablets the next, and Avicel PH-102 tablets remained intact. All tablets, except for those of Avicel PH-102, conformed to the USP drug release requirements. These results conclusively show that UICEL-A/102 and UICEL-XL have the potential to be used as filler, binder, and disintegrant, all-in-one, in the design of tablets containing either a low dose or high dose drug by the direct compression method.     

Design and evaluation of a controlled-release theophylline tablet. Preliminary communication

A 300 mg controlled-release theophylline formulation was developed as a tablet prepared by wet granulation using the acrylic resins Eudragit S 100R and Eudragit RSPMR. The tablet was compared with a marketed controlled-release capsule using in vivo and in vitro tests. The in vitro dissolution of theophylline from the tablets followed an apparent zero order kinetics. The in vivo comparison was performed in a cross over fashion in four healthy volunteers who received one tablet or capsule every 12 hours during seven days. The results showed no statistically significant differences in AUC, tmax and in plasma theophylline concentrations at the different times. Nevertheless, concentrations were lower after the administration of the tablets than when the volunteers received the capsules. On the other hand, the apparent elimination half lives obtained after the tablets were longer than with the capsules. An excessive retardation in the release of theophylline from the tablet could be responsible for this fact.     

左羟丙哌嗪-β-环糊精包合物分散片的制备与评价

目的：优选左羟丙哌嗪-β-环糊精包合物分散片的处方组成与制备工艺。方法：制备左羟丙哌嗪-β-环糊精包合物,并以此为中间体添加适宜的辅料制备分散片。以崩解时限、片剂外观等为评价指标,进行处方及制备工艺的全面考察优化。结果：分散片最优处方为：左羟丙哌嗪-β-环糊精包合物80.0%,L-HPC 10.0%,MCC 9.6%,硬脂酸镁0.4%。其崩解时间不超过60 s,5 min溶出可达85%以上。结论：该分散片处方设计简单合理,工艺稳定可行,符合《中国药典》2015年版的规定。     

Effect of an antacid on gastrointestinal absorption of theophylline.

The effect of a magnesium-aluminum hydroxide antacid (Maalox) on the oral absorption of aminophylline tablets was studied. Twelve healthy adults were administered 200 mg of aminophylline alone or with 30 ml of antacid in a complete crossover study. Blood samples were drawn at 0.33, 0.67, 1, 2, 4, 8, 12, and 24 hours following theophylline (as aminophylline) administration. Theophylline plasma levels were measured by high-performance liquid chromatography. The plasma theophylline concentrations of the group receiving theophylline only were significantly greater than those of the group receiving theophylline plus antacid at the 0.67- and 1-hour sample times only (p less than 0.05). The extent of theophylline absorption and the eliminated rate constant were not significantly affected by the antacid. Antacid significantly decreased theophylline's absorption rate constant (p less than 0.05), indicating a slower absorption of theophylline with antacid. Concurrent administration of the antacid Maalox should not significantly change theophylline's clinical effect.     

Evaluation of the absorption from some commercial enteric-release theophylline products

In a single-dose bioavailability study, Wales, Robinson, Columbia, and Choledyl (Warner/Chilcott) enteric-coated tablets all allowed a bioavailability of theophylline (99%±25%, 102%±23%,103%±18%, and 98%±15%;mean±SD, n=12) statistically indistinguishable from that of the standard uncoated tablet (Searle 200 mg aminophylline). Only the Wales and Choledyl tablets (7.6, 4.2 hr) could be shown (p<0.05) to generate a peak plasma theophylline concentration later than the standard (1.4 hr). All tablet brands demonstrated a significant lag time before appearance of theophylline in the plasma, and both Wales and Choledyl tablets also had a (t _peak -t _tag )statistically different from that of the standard. Despite misleading indications from the mean plasma profile (plasma concentrations at each sampling time averaged over all subjects), plasma data from the individual participants and in vitrodissolution data show that, while release of theophylline from the Wales tablet might be inordinately slow, this is not a sustained-release preparation. Of the enteric-coated tablets only the Columbia product allowed significant levels in the first sample after dosage. Five of the 18 Columbia doses gave rise to 40–99%of the peak concentration in the 1- hr sample. In vitro,it takes 39±14 min for 40% of the theophylline content of Columbia tablets to dissolve in simulated intestinal fluid. Surprisingly rapid delivery of an entericcoated tablet to the duodenum would appear to be required to allow a significant percentage of theophylline to be dissolved and absorbed before 1 hr. None of 12 Columbia tablets tested in vitro,however, allowed dissolution of more than 0.2% of their theophylline content during 1 hr immersion in simulated gastric fluid. Since once in intestinal fluid Columbia tablets appear to dissolve more rapidly than the other enteric products, it is not clear whether the five Columbia tablets in question had imperfections or whether, in fact, this tablet brand more closely than the others represents the ideal of immediate release once in the duodenum. Plasma samples should be taken as early as 15 min after dosage when evaluating the bioavailability of enteric release products.This work was supported by FDA Contract No. 223-74-3145. Data management and analysis were achieved largely by the NIH-sponsored PROPHET system (ref.Proc. Natl. Comput. Conf. Exposition 43:457, 1974). Dr. Guentert was assisted by the Swiss National Science Foundation.     

Characterization of particle deformation during compression measured by confocal laser scanning microscopy

Direct compression of riboflavin sodium phosphate tablets was studied by confocal laser scanning microscopy (CLSM). The technique is non-invasive and generates three-dimensional (3D) images. Tablets of 1% riboflavin sodium phosphate with two grades of microcrystalline cellulose (MCC) were individually compressed at compression forces of 1.0 and 26.8 kN. The behaviour and deformation of drug particles on the upper and lower surfaces of the tablets were studied under compression forces. Even at the lower compression force, distinct recrystallized areas in the riboflavin sodium phosphate particles were observed in both Avicel PH-101 and Avicel PH-102 tablets. At the higher compression force, the recrystallization of riboflavin sodium phosphate was more extensive on the upper surface of the Avicel PH-102 tablet than the Avicel PH-101 tablet. The plastic deformation properties of both MCC grades reduced the fragmentation of riboflavin sodium phosphate particles. When compressed with MCC, riboflavin sodium phosphate behaved as a plastic material. The riboflavin sodium phosphate particles were more tightly bound on the upper surface of the tablet than on the lower surface, and this could also be clearly distinguished by CLSM. Drug deformation could not be visualized by other techniques. Confocal laser scanning microscopy provides valuable information on the internal mechanisms of direct compression of tablets.     

对乙酰氨基酚口腔崩解片的研制

目的 以对乙酰氨基酚（扑热息痛）为模型药物制备新型口服速释剂型口腔崩解片。方法 以崩解时间为指标，采用正交试验筛选片剂的处方组成，并优化制备工艺。结果 以MCC／L-HPC 50：15作为崩解剂，部分制粒压片工艺制得的扑热息痛口腔崩解片，体外平均崩解时间为35s，置于口腔40s内可崩解，无砂砾感，片剂体外溶出度1min可达95％。结论 扑热息痛口腔崩解片于口腔内可迅速崩解，制备工艺简单可行，有效地改善了药物粉末的流动性，适宜于大生产。     

Compaction of enteric-coated pellets: influence of formulation and process parameters on tablet properties and in vivo evaluation.

The aim of this study was to investigate the influence of formulation and compression parameters on the properties of tablets, containing enteric-coated pellets, and on the integrity of the enteric polymer of the individual pellets after compression. In addition the piroxicam plasma concentrations were determined after single and multiple oral administration of powder, pellet and tablet formulations at a dose of 0.3 mg piroxicam/kg bodyweight to dogs. Tablets consisted of enteric-coated pellets (containing 2.5% (w/w) piroxicam in combination with microcrystalline cellulose and sodium carboxymethylcellulose (using Avicel PH 101 and Avicel CL 611 in a ratio of 1-3), cushioning waxy pellets and 10% Kollidon CL (as an external disintegrator). From the D-optimality experimental design it was concluded that the ratio of coated pellets to cushioning pellets (CoP/CuP) affected all tablet properties evaluated. Variation of the pellet size and the CoP/CuP ratio resulted in different in vitro tablet disintegration times. Enteric coating of the pellets or compression of the coated pellets did not have a significant influence (P >0.05) on AUC(0-->72 h). Cmax values obtained after oral administration of coated pellets and compressed coated pellets were significantly lower than for the other formulations. Differences in in vitro tablet disintegration times were not reflected in the onset of the piroxicam plasma concentrations. A dosing interval of 48 h prevented piroxicam accumulation following multiple dose administration.     

Usefulness and safety of theophylline injection form (Theodrip) for the treatment of acute asthma

The effects of the speed of intravenous infusion on the pharmacokinetics of theophylline were studied in 9 healthy volunteers (Ex I). Subjects were intravenously administered either six 4.8 mg/kg theophylline (Theodrip, Nikken Chemicals Co., Ltd., Japan) or three matching placebo injections (4.8 ml/kg physiological saline) for 30 min (Step I) or for 15 min (Step II). In Steps I and II, Cmax was 10.8 +/- 1.1 and 10.8 +/- 0.8 micrograms/ml, respectively. These Cmaxs were concentrations yielding therapeutic effects in patients with acute asthma. Next, comparative pharmacokinetics between theophylline (Theodrip) and aminophylline were examined by a crossover method in 16 healthy volunteers (Ex II). The 90% confidence limits of the differences of mean values were within 80-120% and were 92.8-100.1% for Cmax, 99.7-105.3% for t1/2 and 100.2-104.4% for AUC. Thus, we concluded that the pharmacokinetics of the plasma theophylline after intravenous administration of Theodrip (theophylline at 4.8 mg/kg) were bioequivalent to those of aminophylline (6.0 mg/kg) for 30 min. In Ex I and II, no subjects had adverse effects and in Ex I no influence on ECG was seen. In addition, the convenience of Theodrip was compared with that of ampules of aminophylline among nurse volunteers (Ex III). The times required for set-up of Theodrip were significantly shorter than those of aminophylline ampules. On the other hand, the adverse reactions to aminophylline resulting from hypersensitivity reactions to its ethylenediamine component have been reported. Theodrip consists of 200 mg theophylline and 200 ml physiological saline in a plastic bag. Therefore, Theodrip, which does not contain ethylenediamine, is expected to have less adverse effects and be easier to handle than aminophylline.     

Preparation of ketamine tablets for treatment of patients with neuropathic pain

Ketamine is known to have distinguished analgesic effects without anesthetic when administered in a low dose. Since ketamine is not commercially available except injection forms, we prepared ketamine tablets for the home-care medication of patients with neuropathic pain. The direct compression or wet granulation method was employed to form 150 mg of tablets containing 50 mg of ketamine. The latter method was superior to the former one in terms of content uniformity, weight variation and disintegration tests of the tablets. Ketamine contents in the tablet prepared by the wet granulation method were unchanged for 12 weeks under the conditions of 25 degrees C and 75% relative humidity (RH). The Cmax and AUC0-3 h values for ketamine after administration of the tablet were slightly smaller than those of the syrup in a healthy volunteer. However, analgesic effects of the tablet was similar to that of the syrup in a patient with neuropathic pain. And the tablet was also effective for another four patients with neuropathic pain. These results indicate that ketamine tablets are useful for the home-care medication of patients with neuropathic pain.