Solid self-emulsifying nitrendipine pellets: Preparation and in vitro/in vivo evaluation

Objective of this study is to develop and evaluate the new solid self-emulsifying (SE) pellets of poorly soluble nitrendipine (NTD). These pellets were prepared via extrusion/spheronization technique, using liquid SEDDS (NTD, Miglyol^® 812, Cremophor^® RH 40, Tween 80, and Transcutol^® P), adsorbents (silicon dioxide and crospovidone), microcrystalline cellulose and lactose. The resulting SE pellets with 30% liquid SEDDS exhibited uniform size (800–1000 μm) and round shape, droplet size distribution following self-emulsification was nearly same to the liquid SEDDS (72 ± 16 nm and 64 ± 12 nm). The in vitro release was similar for the two SE formulations (over 80% within 30 min), both significantly higher than the conventional tablets (only 35% within 30 min). The oral bioavailability was evaluated for the SE pellets, liquid SEDDS and conventional tablets in fasted beagle dogs. AUC of NTD from the SE pellets showed 1.6-fold greater than the conventional tablets and no significant difference compared with the liquid SEDDS. In conclusion, our studies illustrated that extrusion/spheronization technique could be a useful large-scale producing method to prepare the solid SE pellets from liquid SEDDS, which can improve oral absorption of NTD, nearly equivalent to the liquid SEDDS, but better in the formulation stability, drugs leakage and precipitation, etc.     

Preparation and in vitro/in vivo evaluation of sustained-release venlafaxine hydrochloride pellets

The objective of this study was to prepare different venlafaxine hydrochloride sustained-release products and to elucidate the influence of composition of the coating film on the in vitro drug release profiles and in vivo pharmacokinetics. Pellets were prepared by a standardized process of extrusion/spheronization. A selected fraction size (0.8-1.0 mm diameter) of pellets of each formulation was coated with Eudragit NE30D or ethylcellulose (10 cps). Many efforts have been made to tailor drug release rate by choosing different coating materials, different percent of pore forming components and coating weight variation to achieve a desired sustained-release effect. The dissolution studies were performed and data were analyzed in terms of cumulative release as a function of time. The influence on the release of venlafaxine from sustained-release capsules was observed in dissolution media of different pH and gradient pH. Scanning electron microscope (SEM) micrographs revealed morphological changes of the pellet coating surface which were related to in vitro drug release profiles. The relative bioavailability for Formulation 1 and Formulation 2 was evaluated in six healthy beagle dogs after oral administration in a fast state using sustained-release capsules (Effexor XR) as a reference. The results suggested that Formulation 1 and Formulation 2 both had better bioavailability compared with Effexor XR. It could be found that there existed quite difference in the in vivo release and oral absorption performances, despite the similar in vitro drug release behavior for the two formulations. It might be attributable to complex in vivo environment and then variation in the release behavior. Thus differences in the film micro-structure and surface roughness caused by aqueous dispersion and organic solvent coating techniques strongly influence the in vivo release and oral absorption performances.     

茴拉西坦自乳化给药系统与片剂的药代动力学及体内外相关性的研究

目的：研究茴拉西坦自乳化制剂和普通片剂的体内外相关关系;评价其大鼠口服给药的体内药代动力学。方法：通过测定自乳化制剂和普通片剂的体外溶出度考察其释药特性,采用RP-HPLC法测定活性代谢产物对氨基甲氧基丁酸的浓度血浆中,通过Wagner-Nelson法计算体内吸收分数（f）,研究两制剂的吸收分数（f）与体外累积溶出度（Q%）的相关性。结果：自乳化微乳体外15min的溶出度为（80±4）%,比片剂的溶出度（50%）明显提高;体内代谢产物的回收率为90%,日内日间精密度分别小于4%和6%,该方法灵敏度高、准确可靠。自乳化微乳的AUC0-∞为（11168±2395）ng·mL^-1·h,是普通片剂的3倍。自乳化微乳和片剂的MRT0-∞分别为（2.7±0.6）h和（1.7±0.5）h,具有统计学差异（P〈0.05）。体内外相关性结果表明,片剂的体内吸收与体外溶出度呈线性相关,线性方程的斜率为0.7765,截距为-2.9527;自乳化微乳的体内外相关性符合二次模型,其拟合系数为0.972。结论：茴拉西坦自乳化给药系统可显著提高药物体内的生物利用度。自乳化制剂处方中含有促吸收的复合表面活性剂和油相,其体外药物呈快速释放的特性,而体内自发与胃肠液形成o/w型微乳后可通过淋巴转运的吸收途径。     

Enhanced oral bioavailability of piperine by self-emulsifying drug delivery systems: in vitro,in vivo and in situ intestinal permeability studies

Abstract

The main purpose of this work was to develop and evaluate a self-emulsifying drug delivery system (SEDDS) of piperine to enhance its solubility and bioavailability. The formulation was optimized by solubility test and ternary phase diagrams. Then physiochemical properties and in vitro release of SEDDS were characterized. In vivo pharmacokinetics study and in situ single-pass intestinal perfusion were performed to investigate the effects of SEDDS on the bioavailability and intestinal absorption of piperine. The optimized formulation was composed of ethyl oleate, Tween 80 and Transcutol P (3:5.5:1.5, w/w), with the level of the piperine reached 2.5% (w/w). The in vitro dissolution rates of piperine SEDDS were significantly higher than the self-prepared capsules. In vivo pharmacokinetic study showed C_max1, C_max2 and area under the curve of piperine after oral administration of SEDDS in rats were 3.8-, 7.2- and 5.2-fold higher than the self-prepared capsules, respectively, and the relative bioavailability of SEDDS was 625.74%. The in situ intestinal absorption study revealed that the effective permeability and the effective absorption rate values of piperine for SEDDS were significantly improved comparing to solutions (p?<?0.01). So SEDDS formulation could improve the oral bioavailability and intestinal absorption of piperine effectively.     

Development and characterization of liquid and solid self-emulsifying drug delivery system of fexofenadine

Fexofenadine, the active metabolite of terfenadine, a well known and effective H1 receptor antagonist, is administered by the oral route. The objective of present investigation was to develop and characterize a liquid self-emulsifying drug delivery system (SEDDS) and a solid SEDDS by using bioenhancer excipients like Tween 80 and Labrasol which are known for their inhibiting action on CYP450 and P-glycoprotein pump. Solubility of fexofenadine was determined in various vehicles, including oils, surfactants and co-solvents. Various evaluation parameters (emulsification study, particle size, poly-dispersibility index, % drug release, etc.) were carried out to find out optimized liquid SEDDS formulation. Optimized liquid formulations were converted in solid SEDDS by simple and convenient physical adsorption technique. Solid SEDDS was characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transport infra-red spectroscopy. The optimized liquid SEDDS formulation contained 29 % Captex 200P/Capmul MCM C8 EP as oil, 47 % Labrasol/Tween 80 as a surfactant and 24 % Ethanol as a co-solvent. The optimized liquid and solid SEDDS showed higher drug release than pure API powder. DSC and XRD results of solid SEDDS confirmed that the drug presented in the formulation was in an amorphous state. The prepared liquid SEDDS and solid SEDDS containing bio-enhancer excipients increased the in vitro dissolution rate of fexofenadine compared to pure drug and has potential to increase bioavailability by blocking Pgp efflux pump and CYP450 hepatic metabolism.     

复方丹参pH依赖型延迟释药微丸在家犬体内的药效动力学

目的制备复方丹参pH依赖型延迟释药微丸填充胶囊并进行家犬体内药效动力学研究。方法分别用HPMC，Eudragit L-30D-55，Eudragit L100/S100 (1∶6)包衣制备pH依赖型延迟释药微丸，测定体外释放曲线，并用血清药理学方法进行家犬体内的药效动力学研究。结果制备了复方丹参pH依赖型延迟释药微丸，体外溶出曲线呈pH依赖特征。单剂量给药后自制速释片R的药效动力学参数T_max为0.58 h，E_max为34.63%，延迟释药胶囊T1和T2的T_max分别延长至2.42和3.17 h，E_max分别降低至13.57%和14.52%，相对生物利用度分别为99.3%和133.6%。多剂量给药后自制速释片R波动度DF 7.32，延迟释药胶囊T1和T2的波动度DF 3.40和3.03。结论复方丹参pH依赖型延迟释药胶囊体外释放具有pH依赖特征，体内具有明显的延迟释药作用，多剂量达到稳态时，药效动力学波动系数低于普通片。     

靛玉红及其磷脂复合物和自乳化释药系统在犬体内的药动学

目的:考察靛玉红及其磷脂复合物和自乳化释药系统在犬体内的药动学过程。方法:采用三周期交叉试验设计法,取6条健康beagle犬随机分成3组,分别服用剂量为100mg的靛玉红片、靛玉红磷脂复合物和靛玉红自乳化释药系统,用高效液相色谱(HPLC)法测定靛玉红的血药浓度,利用3P97软件包和统计矩方法计算主要药动学参数和相对生物利用度。结果:以靛玉红片为对照,靛玉红磷脂复合物和自乳化释药系统的相对生物利用度分别为(157±s 10)%和(162±16)%。结论:磷脂复合物和自乳化释药系统有利于改善靛玉红口服生物利用度。     

Self-emulsifying drug delivery systems (SEDDS) of coenzyme Q10: formulation development and bioavailability assessment

The goals of our investigations are to develop and characterize self-emulsifying drug delivery systems (SEDDS) of coenzyme Q10 (CoQ10), using polyglycolyzed glycerides (PGG) as emulsifiers and to evaluate their bioavailability in dogs. Solubility of CoQ10 was determined in various oils and surfactants. SEDDS consisted of oil, a surfactant and a cosurfactant. Four types of self-emulsifying formulations were prepared using two oils (Myvacet 9-45 and Captex-200), two emulsifiers (Labrafac CM-10 and Labrasol) and a cosurfactant (lauroglycol). In all the formulations, the level of CoQ10 was fixed at 5.66% w/w of the vehicle. The in vitro self-emulsification properties and droplet size analysis of these formulations upon their addition to water under mild agitation conditions were studied. Pseudo-ternary phase diagrams were constructed identifying the efficient self-emulsification region. From these studies, an optimized formulation was selected and its bioavailability was compared with a powder formulation in dogs. Medium chain oils and Myvacet 9-45 provided higher solubility than long chain oils. Efficient and better self-emulsification processes were observed for the systems containing Labrafac CM-10 than formulations containing Labrasol. Addition of a cosurfactant improved the spontaneity of self-emulsification. From these studies, an optimized formulation consisting of Myvacet 9-45 (40%), Labrasol (50%) and lauroglycol (10%) was selected for its bioavailability assessment. A two-fold increase in the bioavailability was observed for the self-emulsifying system compared to a powder formulation. SEDDS have improved the bioavailability of CoQ10 significantly. The data suggest the potential use of SEDDS to provide an efficient way of improving oral absorption of lipophilic drugs.     

Comparative bioavailability study in dogs of a self-emulsifying formulation of progesterone presented in a pellet and liquid form compared with an aqueous suspension of progesterone

A pellet formulation of progesterone in a self-emulsifying system (SES) was prepared by the process of extrusion/spheronization to provide a good in vitro drug release (100% within 30 min, T(50%) at 13 min). A three-way randomized crossover study was performed in six fasted male beagle dogs with these pellets and the same SES liquid formulation, both contained in a hard shell capsule, and an aqueous suspension. The same dose of progesterone (16 mg) in pellets and in the SES liquid formulation resulted in similar AUC, C(max) and T(max) values, estimated from progesterone plasma levels by (125)I radioimmunoassay. Although the maximum absorption was slightly retarded (0.5 to 1 h) by SES (pellets and liquid), AUC and C(max) were approximately seven and nine times greater then those obtained when an aqueous suspension formulation of the same dose of progesterone was administered to the same dogs. These results showed that it was possible to improve the bioavailability of the poorly soluble, poorly permeable progesterone when administered in SES. Moreover, presenting the progesterone in the form of a pellet did not prevent the release of the drug in vivo. These data demonstrate the utility of extrusion/spheronization in delivering a nonaqueous system in a novel solid dosage form.     

自乳化药物传递系统的研究进展

本文对近几年国内外有关自乳化药物传递系统的特点、吸收机制、组成、影响因素及其在药剂学方面的应用进行了归纳和分析。自乳化药物传递系统可显著地提高难溶性或亲脂性药物口服生物利用度，具有广阔的发展前景。     

Formulation and in vivo evaluation of chlorpropham (CIPC) oral formulations

The objective of these studies was to examine the in vivo performance of oral formulations of chlorpropham (CIPC). In order to develop a new oral formulation several different solubilization techniques were evaluated, namely: cosolvents, surfactants, and complexing agents. The solubilization data indicated that a conventional solution formulation was not plausible. Two self-emulsifying drug delivery systems (SEDDS) were developed and evaluated for stability. Both SEDDS formulations were found to be chemically stable. In vivo analysis of a SEDDS formulation, a suspension formulation and an intravenous bolus dose was conducted in F344 rats. Pharmacokinetic analysis of the formulation data indicated that the SEDDS formulation provided only marginally better oral bioavailability compared to a suspension formulation. While SEDDS formulations often result in greater bioavailability this was not observed for CIPC. In vivo analysis indicate that CIPC results in a situation where the dissolution rate of CIPC from the suspension is not rate limiting, rather the absorption rate in the GI tract is rate-limiting. This paradigm is the result of CIPCs low melting point and the relatively small particle size of the suspension which facilitate the dissolution in the GI tract.     

离心造粒包衣法制备洛索洛芬钠缓释微丸及体外释放度考察

目的:制备洛索洛芬钠缓释微丸。方法:采用离心造粒包衣法制备洛索洛芬钠微丸。首先制备微晶纤维素空白母核和洛索洛芬钠含药素丸,并在此基础上进行丙烯酸树脂水分散体(Eudragit NE30D、Eudragit L30D-55)包衣,并对包衣微丸的释药特征进行探讨。结果:微晶纤维素(MCC)空白母核32～40目的收率约78.6%,含药素丸18～24目收率约88.2%,使用Eudragit NE30D和Eudragit L30D-55比例是20:1的包衣液,包衣增重10%。包衣干燥后,即得洛索洛芬钠缓释微丸,洛索洛芬钠缓释胶囊体外释药行为较好地符合Higuchi方程。结论:在优化的工艺条件下可制得表面光滑、圆整度高的洛索洛芬钠缓释微丸。     

Design and study of ibuprofen disintegrating sustained-release tablets comprising coated pellets.

One challenge in tableting of sustained-release multiparticulates is maintaining the desired drug release after compaction. The aim of this study was to design sustained-release ibuprofen tablets which upon oral ingestion rapidly disintegrate into sustained-release pellets in which the integrity of the pellet core and/or coat is preserved. First free films composed of Eudragit RS 30D and RL 30D in 4:1 ratio and containing different levels of triethyl citrate (TEC) were prepared and tested to optimize the plasticizer level. Cured Eudragit based pellets with 60% ibuprofen loading which in our previous study showed proper mechanical properties for compression were coated with Eudragit RS 30D/RL 30D (4:1) containing 20% triethyl citrate at different coating levels. The mechanical properties of the coated pellets were tested. Polymer coated pellets were compacted into tablets either alone or with a blend of excipients comprising Avicel, PEG 4000, cross-linked PVP. A 3(2) full factorial design was used to optimize the filler blend composition. Effects of pellet to filler ratio, compression force and granulation of filler on tablet characteristics were investigated. Results of mechanical test showed that the coating of cured pellets had no significant effect on yield point and elastic modulus of the pellets. In the case of 5% coating level sustained release of ibuprofen over a period of 24h was achieved. The results obtained from tableting procedure showed that by selecting suitable filler blend (60% Avicel, 10% cross-linked PVP and 30% PEG 4000), compression force, and granulation of filler it was possible to prepare sustained-release tablets containing high ratio of coated pellets (even 80%) with desirable strength, disintegration time, and drug release rate. It was observed that compression force, pellet to filler ratio, composition of filler blend and granulation of fillers had no effect on drug release rate from compacted pellets but had significant influence on tablet strength, friability, and disintegration time. SEM graphs and in vitro release profiles for compacted pellets showed no apparent damage to the coated pellets as a result of the compaction process.     

Dissolution and absorption behavior of meclizine dihydrochloride from soft gelatin capsules

Two kinds of soft gelatin capsules containing meclizine dihydrochloride (MZ) were prepared by using a medium-chain length triglyceride as a base. One is a self-emulsifying type, and the other is an oil dispersing type. The release of MZ from soft capsules and its in vivo absorption behavior were examined and compared with those of a commercial tablet. The release of MZ from the self-emulsifying soft capsule which was only slightly affected by pH was greater than those from the oil dispersing soft capsule and commercial tablet. The serum levels of MZ after the administration of preparations orally to beagle dogs increased in the order of self-emulsifying soft capsule, commercial tablet, oil dispersing soft capsule. This result suggests that the self-emulsifying soft capsule is useful for the increase of the bioavailability of the drug.     

Extrusion-spheronization of pH-sensitive polymeric matrix pellets for possible colonic drug delivery

The aim of this study was to investigate extrusion-spheronization pelletization for preparing pH-sensitive matrix pellets for colon-specific drug delivery. The effects of three independent variables (amounts of Eudragit S, citric acid and spheronizing time) on pellet size, shape (roundness and aspect ratio), and drug release were studied with central composite design. The pellets contained ibuprofen as a model drug, citric acid as a pH-adjusting agent, Eudragit S as a pH-sensitive binder and microcrystalline cellulose (MCC). The pellets were prepared with Nica extrusion-spheronizing equipment and subsequently enteric-coated using an air-suspension technique. Eudragit S as a pH-sensitive matrix former in pellets increased the pellet size and influenced pellet roundness. In small amounts Eudragit S increased pellet roundness but in larger amounts pellet roundness was reduced. Citric acid promoted the pelletization process resulting in a narrower area distribution. The pH-sensitive matrix pellet failed to delay the drug release. The combination of citric acid and enteric coating, however, delayed the drug release for 15 min in a pH 7.4 phosphate buffer.     

Development of a supersaturable SEDDS (S-SEDDS) formulation of paclitaxel with improved oral bioavailability

A new, supersaturable self-emulsifying drug delivery system (S-SEDDS) of paclitaxel was developed employing hydroxypropyl methylcellulose (HPMC) as a precipitation inhibitor with a conventional SEDDS formulation. In vitro dilution of the S-SEDDS formulation results in formation of a microemulsion, followed by slow crystallization of paclitaxel on standing. This result indicates that the system is supersaturated with respect to crystalline paclitaxel, and the supersaturated state is prolonged by HPMC in the formulation. In the absence of HPMC the SEDDS formulation undergoes rapid precipitation, yielding a low paclitaxel solution concentration. A pharmacokinetic study was conducted in male Sprague-Dawley rats to assess exposure after an oral paclitaxel dose of 10 mg/kg in the SEDDS formulations with (S-SEDDS) and without HPMC. The paclitaxel S-SEDDS formulation shows approximately 10-fold higher maximum concentration (C(max)) and five-fold higher oral bioavailability (F approximately 9.5%) compared with that of the orally dosed Taxol formulation (F approximately 2.0%) and the SEDDS formulation without HPMC (F approximately 1%). Coadministration of cyclosporin A (CsA), an inhibitor of P-glycoprotein and CYP 3A4 enzyme, at a dose of 5 mg/kg with the S-SEDDS formulation further increased the oral bioavailability (F approximately 22.6%). This assessment demonstrates that the systemic exposure of paclitaxel following oral administration can be substantially improved via the S-SEDDS approach.     

Investigation for the quality factors on the tablets containing medicated pellets

Sustained and controlled pellets are considered as one of the ideal dosage forms. Due to the large coverage area of pellets, loaded drugs can be absorbed completely in the body and bioavailability is improved correspondingly. Coated pellets-containing tablet is a special oral formulation consisting of various pellets with different release rate. Desired rate of drug release rate can be achieved by adjusting the proportion of pellets. However, this formulation faces strict requirements in the process of preparation. Several factors will influence release behavior of tablets, including pellet cores, coating, and tabletting. Therefore, these factors will be investigated sufficiently in this review to provide valuable information for manufacturing process.     

Preparation and in vitro/in vivo evaluation of sustained-release metformin hydrochloride pellets.

In this study, metformin hydrochloride (MH) sustained-release pellets were successfully prepared by centrifugal granulation. Seed cores preparation, drug layering, talc modification and coating of polymeric suspensions were carried out in a centrifugal granulator. Talc modification was performed before coating in order to overcome the high water solubility of metformin. The influence of surface modification by talc, the effects of Eudragit types and ratios, as well as the correlation between in vitro release and in vivo absorption were investigated in detail. Experimental results indicated that talc modification made a decisive contribution to controlling the drug release by avoiding drug dumping. Three dissolution media: 0.1 M HCl, distilled water and pH 6.8 phosphate buffer were employed to determine the in vitro release behaviors of the above metformin hydrochloride pellets. The relative bioavailability of the sustained-release pellets was studied in 12 healthy volunteers after oral administration in a fast state using a commercially available immediate release tablet (Glucophage) as a reference. Following coating with a blend of Eudragit L30D-55 and Eudragit NE30D (1:20), at 7% or 10% coating level, respectively (referred to as F-2, F-3), the pellets acquired perfect sustained-release properties and good relative bioavailability. The Cmax, Tmax and relative bioavailability for F-2 and F-3 coated pellets were 1.21 microg/ml, 6 h, 97.6% and 1.65 microg/ml, 8 h, 165%, respectively. Combined use of two Eudragit polymers with different features as coating materials produced the desired results. Restricted delivery of metformin hydrochloride to the small intestine from differently coated pellets resulted in increased relative bioavailability and a sustained release effect. The adoption of several different pH dissolution media established a better relationship between the in vitro release and in vivo absorption of the sustained-release pellets.     

In-vitro and in-vivo evaluation of enteric-coated starch-based pellets prepared via extrusion/spheronisation

Pellet cores containing modified starch (high-amylose, crystalline and resistant starch) as the main excipient were enteric-coated with an Eudragit L30 D-55 based dispersion. The polymer weight gain was from 15% to 30% (w/w). Pellet cores were prepared using piroxicam (2.5% w/w, poor water solubility) and anhydrous theophylline (2.5% and 25% w/w, coarse and micronised powder, medium water solubility) as model drugs. Next to the water solubility, particle size and concentration of the model drugs, the influence of sorbitol (0% and 10%, w/w) and drying method (oven and fluid-bed) on pellet yield, size (Feret mean diameter), sphericity (aspect ratio, AR and two-dimensional shape factor, e(R)), friability, surface morphology and drug release were evaluated. Binder (HPMC) and granulation liquid (water) concentration were optimised to obtain maximum yield (size fraction between 900 and 1400 microm) and acceptable sphericity (AR<1.2). Pellet friability was <0.01% for all formulations, while the mean pellet diameter was lower for pellets with sorbitol and the ones dried in an oven. Mercury intrusion porosimetry combined with scanning electron microscopy revealed an influence of drying method and sorbitol level on the surface structure: the surface of fluid-bed dried pellets without sorbitol and with 2.5% of model drug was cracked, which correlated with a Hg-intrusion peak at the 6-80 microm pore size range. Due to improved mechanical properties of the wet mass, sorbitol addition smoothened the pellets as the main peak of Hg-intrusion shifted to a smaller pore size range. Using a higher drug concentration and micronised theophylline shifted the main peak of Hg-intrusion further towards the smaller pore size range. Oven-dried pellets showed no Hg-intrusion and no cracks were observed. When applying the highest coating thickness (30% weight gain), all theophylline pellet formulations were successfully coated (<10% drug release after 2h in acid dissolution medium), while pellets with the lowest coating thickness (15% weight gain) released from 5% to about 30% theophylline. The extent of drug release depended on the pellet composition and drying method as these factors determined the surface properties. Piroxicam release in acid medium was less than 1% irrespective of the surface characteristics, due to its poor water solubility. In basic medium (phosphate buffer, pH 6.8) all pellets released the drug in less than 45 min. The bioavailability of coated and uncoated piroxicam pellets was determined after oral administration to six dogs. Values of AUC(0-->72h), C(max) and t(max) after oral administration of piroxicam pellets to dogs were not significantly different from the values obtained for immediate release capsules (P>0.05).     

Suitability of κ-carrageenan pellets for the formulation of multiparticulate tablets with modified release

κ-Carrageenan is a novel pelletisation aid with high formulation robustness and quick disintegration leading to fast drug release unlike the matrix-like release from non-disintegrating microcrystalline cellulose pellets. Compression of pellets into tablets is cost effective. The feasibility of formulating multiparticulate tablets with coated κ-carrageenan pellets was investigated. Pellets containing a highly soluble drug in acid, namely bisacodyl and κ-carrageenan or MCC as pelletisation aid were prepared, enteric coated with a mixture of Kollicoat(?) MAE 30 DP and Eudragit(?) NE 30 D and compressed using silicified microcrystalline cellulose as embedding powder. The effect of coating level, type of pellet core, compression force and punch configurations on drug release were studied. A sufficient coating thickness for κ-carrageenan pellets was necessary to obtain multiparticulate tablets with adequate resistance in the acid stage regardless of the compression pressure used. While κ-carrageenan pellets and their tablets released over 80% of the drug during the neutral stage only about 20-24% was released from MCC pellets and their tablets. The type of punches used (oblong or round) did not significantly influence the drug release from the prepared tablets. Moreover, sufficient prolonged release properties were obtained with κ-carrageenan pellets containing theophylline as a model drug and coated with Kollicoat(?) SR 30 D using Kollicoat(?) IR as pore former. A lower coating level and higher amount of pore former were needed in case of theophylline pellets formulated with MCC as pelletisation aid. The sustained release properties of both coated pellet formulations were maintained after compression at different compression pressures.