Sustained-release Pellets Research Articles

Preparation and pharmacokinetics in beagle dogs of ganershu sustained-release pellets.

Background:The active ingredients of Ganershu compound recipe, which are effective for hepatitis treatment in liver protection and transaminase reduction. However, the active ingredients of Ganershu compound recipe are poor absorption, which conduct it has a low oral bioavailability.Objective:We prepared Ganershu sustained-release pellets (GSPs) by fluidized-bed on central composite design-response surface methodology and increase its bioavailability in beagle dogs.Materials and Methods:In this study, GSPs were successfully prepared. The Drug-loaded pellets and sustained-release coated were carried out in fluidized-bed machine. GSP was optimized for fitting release, roundness, and the overall desirability by central composite design-response surface methodology.Results:To optimize cumulative release profile, the outermost ethyl cellulose coating layer and the hydroxypropyl methyl cellulose (HPMC) swelling layer were employed, which were respectively given coating levels in terms of weight gain of 22% and 6%, the concentration of HPMC is 4.5% (g/ml). The pharmacokinetics of Ganershu normal pellets (GNPs) and GSP was studied in beagle dogs after oral administration. The naringenin as an index, the area under the curve0-∞ of naringenin in GSP was 1.38 times greater than that of GNP. Meanwhile, Tmax of GSP was prolonged for about 74%.Conclusion:This study can clearly indicate that we enhanced the oral bioavailability of Ganershu by preparing the GSP, which had the sustained dissolution and improved the potential of it for clinical application.

Sustained-release pellets of nifedipine using microcrystals combined with MCC-based matrix

The purpose of this study was to prepare sustained-release pellets of nifedipine (NSPs) based on MCC matrix. Wet-milling and extrusion-spheronization techniques were employed to prepare the microcrystals and pellets, respectively. The drug release mechanism and the influencing factors were investigated. After milled with HPMC (E5), the mean particle size of nifedipine in co-grinding mixture (CGM) was 5 μm, which is 15-fold smaller than that of raw material. DSC, X-ray powder diffraction and microscopic observation confirmed the microcrystals of drug were maintained in the CGM. With increased milling time and the content of HPMC, the dissolution rate was greatly enhanced compared with the raw material. The NSPs prepared by MCC and the CGM, which was obtained by cogrinding nifedipine with 5% HPMC solution for 210 min, exhibited sustained release pattern within 8 h. Nifedipine release from MCC-based NSPs followed the Korsmeyer model and closely related to the microstructure of pellet. High stability of NSPs was confirmed after 6 months of accelerated stability test. Using commercially available sustained product as reference, bioequivalence study in beagle dogs was executed and two formulations were bioequivalent. This sustained release pellet formulation of nifedipine was advantageous with convenient and easy scaled-up preparation process.

Vascularization and cellular isolation potential of a novel electrospun cell delivery vehicle

A clinical need exists for a cell delivery device that supports long-term cell viability, cell retention within the device and retrieval of delivered cells if necessary. Previously, cell isolation devices have been based on hollow fiber membranes, porous polymer scaffolds, alginate systems, or micro-machined membranes. We present the development and characterization of a novel dual porosity electrospun membrane based device, which supports cellular infiltration and vascularization of its outer porous layer and maintains cellular isolation within a lumen bounded by an inner low porosity layer. Electrospinning conditions were initially established to support electrospun fiber deposition onto nonconductive silicone surfaces. With these parameters established, devices for in vivo evaluations were produced using nylon as a nonconductive scaffold for deposition of dual porosity electrospun fibers. The outer porous layer supported the development of a penetrating microcirculation and the membrane supported the transfer of insulin from encapsulated sustained release pellets for 4 weeks. Viable cells implanted within the device could be identified after 2 weeks of implantation. Through the successful demonstration of survival and cellular isolation of human epithelial cells within the implanted devices and the ability to use the device to deliver insulin, we have established the utility of this device toward localized cell transplantation. The cell delivery device establishes a platform to test the feasibility of approaches to cell dose control and cell localization at the site of implantation in the clinical use of modified autologous or allogeneic cells.

Design and evaluation of sustained release pellets of aceclofenac

AimThe aim of the present study was to prepare sustained release pellets of aceclofenac using pelletization technique. MethodsThe sustained release was ensured by coating the pellets with ethyl cellulose N50 and hydroxy propyl methyl cellulose E5. The influence of rate retarding polymer, ethyl cellulose in combination with film forming agent, HPMC in different weight ratios on drug release kinetics was studied. ResultsThe in vitro dissolution studies of aceclofenac from the sustained release pellets were carried out in pH 6.8 phosphate buffer using USP type I apparatus. Statistically significant differences were found among the drug release profile from different formulations. ConclusionThe kinetic study revealed that the release of drug from the optimized formulation was appeared to follow first order kinetics. The dissolution profile and in vitro release kinetics showed that aceclofenac pellets were promising for sustained delivery of the drug.

Design, in vitro release characterization and pharmacokinetics of novel controlled release pellets containing levodropropizine

This study was performed to investigate the in vitro release characteristics of levodropropizine (LDP) from novel dual-coated sustained release (SR) pellets, and evaluate the pharmacokinetics of a novel controlled release (CR) preparation composed of the dual-coated SR pellets and immediate release (IR) LDP pellets. The dual-coated SR pellets composed of a drug-loaded nonpareil core, a sub-coating layer (HPMC 6cps) and an SR-coating layer (Aquacoat® ECD, Eudragit® RS 30D or Kollicoat® SR 30D) were prepared by a bottom-spray fluidized bed-coating method. The drug release from the dual-coated SR pellets coated with Aquacoat® ECD followed a zero-order profile in water, and the drug release was not affected by the coating level of the sub-coating layer and stable under the accelerated storage condition (40 °C, 75% RH) for 6 months. The CR preparation showed significantly decreased values of maximum drug concentration (Cmax) and elimination rate (K) than the reference product (LEVOTUS® SYR) but the similar bioavailability (F = 95.43%). The novel CR preparation presents promising delivery of LDP with an immediate and sustained release manner, with similar clinical effect as the commercial IR product.

Pharmacokinetics of diltiazem hydrochloride delay-onset sustained-release pellet capsules in healthy volunteers

The pharmacokinetics (PK) of ordinary tablets and sustained release capsules of diltiazem hydrochloride in human clinical trials had been studied. The PK of diltiazem hydrochloride delay-onset sustained-release pellet capsules, a new dosage form, has not been reported, although it is very important to clinical use. In this paper, we investigated the PK of diltiazem hydrochloride delay-onset sustained-release pellet capsules and the food influence in Chinese healthy volunteers. The PK parameters indicated that the diltiazem hydrochloride delay-onset sustained-release pellet capsules appeared marked characteristics of delayed and controlled release. An opened-label, randomized and parallel clinical trial was conducted in 36 Chinese healthy volunteers with single oral dose (90 mg, 180 mg or 270 mg) and a multiple oral dose (90 mg d-1×6 d) administration. The effect of food on the PK of one single oral dose (360 mg) was investigated in 24 healthy Chinese volunteers. Plasma diltiazem concentration was determined by reversed-phase high-performance liquid chromatography (RP-HPLC) and the main pharmacokinetic parameters were analyzed by PKSolver (Ver 2.0). All clinical studies were conducted in the Clinical Pharmacological Center (No. JDX1999064) of Xiangya Hospital Affiliated Central South University, China. The PK parameters suggested that the new formulation had marked characteristics of delayed and controlled release of diltiazem, and food intake did not alter significantly diltiazem pharmacokinetic parameters.

Design of sustained release pellets of ferrous fumarate using cow ghee as hot-melt coating agent.

Introduction:The objective of the present study was to design ferrous fumarate (FF) sustained release (SR) pellets using of cow ghee (CG) as an important hot-melt coating (HMC) agent.Materials and Methods:The pellets were coated by HMC technique using CG and ethyl cellulose composition by conventional coating pan without the use of spray system. FF formulated as pellets and characterized with regard to the drug content and physico-chemical properties. Stability studies were carried out on the optimized formulation for a period of 6 months at 40 ± 2°C and 75 ± 5% relative humidity.Results:Pellets with good surface morphology and smooth texture confirmed by stereo micrographs. HMC is easy, efficient, rapid and simple method since virtually no agglomeration seen during coating. In-vitro release from pellets at a given level of coating and for present pellet size was dependent upon the physico-chemical property of the drug and mostly aqueous solubility of the drug. The selection of optimized FF formulation was confirmed by comparing percent cumulative drug release with theoretical release profile. Formulation F2 had difference factor (f1) and similarity factor (f2) values was found to be 5 and 66 respectively. F2 showed SR of drug for 8 h with cumulative per cent release of 98.03 ± 4.49%. Release kinetics indicates approximately zero order release pattern. HMC pellets were stable during the course of stability study.Conclusions:By means of HMC using CG and ethyl cellulose, SR pellets containing FF were successfully prepared.

Preparation and Evaluation of Sustained-Release Doxazosin Mesylate Pellets

Doxazosin mesylate (DXM) sustained release pellets were prepared by an extrusion-spheronization and fluid-bed coating technique. The core pellets containing DXM were prepared by extrusion-spheronization technique, and coated by a fluid-bed coater to control the release of DXM. The factors affecting to properties of pellets, such as diluent content, type and coating level of coating agents and plasticizers were studied in the present study. Polymethacrylate derivatives (Eudragit® RS PO and RL PO) were used for coating agents, and polyethylene glycol 6000 (PEG 6000), triethyl citrate (TEC) and castor oil were as plasticizers. To evaluate the properties of prepared pellets, the size of prepared pellets was investigated by sieve analysis technique and the morphology of pellets was evaluated by scanning electron microscopy. Through the dissolution test, factors that have an effect on the dissolution of the drug were evaluated. As the content ratio of microcrystalline cellulose (MCC) had increased, the dissolution was proportionally sustained. Eudragit® RS PO had more marked sustaining effect on the dissolution rate than Eudragit® RL PO, and the effect was more pronounced with the increased coating level. PEG 6000 was an appropriate plasticizer for DXM pellets, and increasing the content of PEG 6000, was also slightly decreasing the dissolution rate.

In vitro and in vivo évaluation of naringin sustained-release pellets compared with immediate-release tablets

Naringin, which is widely present in foods of plant origin and traditional Chinese medicines, has been reported to possess various biological and pharmacological properties. Unfortunately, its short half-life (t 1/2 ) restricts its use as an oral dosage form. In this study, immediate-release (IR) tablet and sustained-release (SR) pellet forms of naringin were prepared to solve this problem. Low-substituted hydroxypropyl cellulose (L- HPC) was chosen as a disintegrant in the IR tablets. In the SR pellets, microcrystalline cellulose (MCC) acts as a matrix former in wet extrusion processes. Sodium dodecyl sulfate (SDS) and sodium chloride (NaCl) increased the drug release rate. In vitro, pellets sustained a release effect for 12 h while the tablets released completely during the first half hour. In vivo, pellets showed a 2.7-fold higher t 1/2 , a lower C max and an equal T max compared with the tablets; and the relative bioavailability of SR pellets to IR tablets was 119.6%.

Formulation and evaluation of sustained release enteric-coated pellets of budesonide for intestinal delivery

Introduction:The aim of present work was to develop intestinal-targeted pellets of Budesonide, a potent glucocorticoid, used for the treatment of ulcerative colitis and Crohn's disease by extrusion and spheronization method. Current available oral formulations of Budesonide have low efficacy because of the premature drug release in the upper part of the gastrointestinal tract. In this study, a pH-controlled intestinal-targeted pellet of budesonide was established using 32 full factorial design by giving an enteric coating with Eudragit S100.Materials and Methods:Budesonide-sustained release pellets were prepared by extruder and spheronization technique using a combination of water-soluble and permeable polymers by applying 32 full factorial design. The pellets were coated by spray coating technique using Eudragit S100 as an enteric polymer. The pellets were characterized for its flowability, sphericity, friability, and in vitro drug release. Release behaviour was studied in different pH media. The release profile was studied for the mechanism of drug release.Result:The optimized formulation showed negligible drug release in the stomach followed by release for 12 h in the intestinal pH. Differential scanning calorimetry and Fourier Transform Infrared Spectroscopy studies indicated no interaction between drug and polymer. Scanning Electron Microscopy image of coated pellets suggested a uniform and smooth coat over the surface of pellets. Accelerated stability studies showed a stable nature of drug in the formulation. All evaluation parameter showed that pellets were good in spherocity and flowability.Conclusion:Sustained release pellets of Budesonide could be prepared by extrusion and spheronization which released the drug in intestinal pH for an intestine to treat inflammatory bowel disease. A ratio of polymer combination could be decided using a full factorial design.

Release Behavior of Tanshinone IIA Sustained-Release Pellets Based on Crack Formation Theory

The objective of this study was to investigate the drug release mechanism and in vivo performance of Tanshinone IIA sustained-release pellets, coated with blends of polyvinyl acetate (PVAc) and poly(vinyl alcohol)-poly(ethylene glycol) (PVA-PEG) graft copolymer. A formulation screening study showed that pellets coated with PVAc-PVA-PEG at a ratio of 70:30 (w/w) succeeded in achieving a 24 h sustained release, irrespective of the coating weight (from 2% to 10%). Both the microscopic observation and mathematical model gave further insight into the underlying release mechanism, indicating that diffusion through water-filled cracks was dominant for the control of drug release. In vivo test showed that the maximum plasma concentration of sustained-release pellets was decreased from 82.13 ± 17.05 to 40.50 ± 11.72 ng mL as that of quick-release pellets. The time of maximum concentration, half time, and mean residence time were all prolonged from 3.80 ± 0.40 to 8.02 ± 0.81 h, 4.28 ± 1.21 to 8.18 ± 2.06 h, and 8.60 ± 1.59 to 17.50 ± 2.78 h, compared with uncoated preparations. A good in vitro-in vivo correlation was characterized by a high coefficient of determination (r = 0.9772). In conclusion, pellets coated with PVAc-PVA-PEG could achieve a satisfactory sustained-release behavior based on crack formation theory.

Preparation and evaluation of sustained release pellets of Tramadol

Preparation of sustained release dosage forms is one of the main objectives in drug formulation. Tramadol is a centrally acting synthetic opioid analgesic used in treating severe pain. In this study, Tramadol sustained release pellets were prepared using two methods and the effect of type, ratio of polymers and plasticizers on drug loading and drug release profile was studied. From the results obtained, it seems that Eudragit RL is not a suitable choice when Tween was used as plasticizer. Moreover, when mixture of Eudragit S and RS were applied as polymers, the optimum drug release profile was obtained and after 10 h, 95% of loaded drug was released. Key words: Eudragit, tramadol, sustained release, plasticizer, pellet.

Preparation of lipid aspirin sustained-release pellets by solvent-free extrusion/spheronization and an investigation of their stability

A novel solvent-free extrusion/spheronization technique was investigated for preparing stable aspirin sustained-release pellets. Lipids as binders and the matrix in this technique were extruded below their melting points, and spheronized in a thermomechanical process. Four types of lipids (adeps solidus, Compritol® 888 ATO, Precirol® ATO5 and Compritol® HD5 ATO) and their admixture in different ratios were used to obtain spherical and extended-release pellets. Pellets containing 80% aspirin, 15% adeps solidus and 5% Compritol® 888 ATO had the best spherical geometry and met the dissolution requirements of aspirin extended-release tablets in USP 31. Storage stability studies showed that the content of free salicylic acid increased sharply in the traditional pellets produced by wet extrusion/spheronization, from 1.91 to 7.84%, whereas there was little increase in the lipid pellets (from 0.48 to 1.08%). The dissolution rate from the optimal pellets (F11) stored at 26°C did not change, but became faster at 40°C/RH75% after 5 months. Powder X-ray diffraction, scanning electron microscopy (SEM) and differential scanning calorimetry were used to investigate the physical properties of the pellets during stability testing. The increase in the rate of drug release from aged pellets (40°C/RH75%) may result from the partially melted adeps solidus observed in SEM photographs. This study suggests that it is possible to prepare sustained-release pellets by solvent-free extrusion/spheronization using an appropriate mixture of lipids with high stability. In particular, this novel technique is excellent for hygroscopic drugs.

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

The aim of this study was to prepare carteolol hydrochloride matrix sustained-release pellets, and to compare its performance in vivo with carteolol common tablets. The formula was optimized according to the roundness and the release of pellets with single-factor, and orthogonal test. The carteolol hydrochloride matrix sustained-release pellets were got by extrusion-spheronisaion, while the release rate in vitro was determined by rotate basket method with UV detection. The carteolol hydrochloride sustained release property was studied in New Zealand white rabbits after oral administration. The optimized prescription is composed of carteolol hydrochloride 5.5 g, MCC 6.0 g, SA 26.3 g, EC 21.0 g, CMC-Na 1.2 g. Drug release property in vitro were as follows: the release time is over 12 h, the drug release behaviors follow the first order equation and the process of drug releasing is drug diffusion with frame erosion. The Cmax, Tmax and AUC(0→24) of the pellets were 2.58 ± 0.43 (mg/ml), 4.20 ± 0.87 (h) and 22.19 ± 4.23 (mg/ml h), respectively. The Cmax, Tmax and AUC(0→24) of the tablets were 3.75 ± 0.59 (mg/ml), 1.00 ± 0.72 (h) and 18.70 ± 3.75 (mg/ml h). The carteolol hydrochloride sustained-release pellets have reasonable formulation and simple preparation technology; the pellets acquired perfect sustained-release properties in vitro/in vivo. Key words: Carteolol hydrochloride, sustained-release, pellets, in vitro, in vivo, evaluation

Characterization and evaluation of self-microemulsifying sustained-release pellet formulation of puerarin for oral delivery

The present study aims to develop self-microemulsifying drug delivery systems (SMEDDS) in sustained-release pellets of puerarin to enhance the oral bioavailability of puerarin. The performances of puerarin–SMEDDS including oils, emulsifiers, and co-emulsifiers were evaluated. Pseudo-ternary phase diagrams shows that the optimized formulation consisted of castor oil as the oil phase, Cremophor® EL as the emulsifier, and 1,2-propanediol as the co-emulsifier. SMEDDS sustained-release pellets were prepared via extrusion–spheronization. The particle size distributions of the formulations were determined using transmission electron microscopy and scanning electronic microscopy. The mean particle size was 50±8nm. The pharmacokinetics and bioavailability of the puerarin–SMEDDS sustained-release pellets and puerarin tablets were evaluated and compared in beagle dogs. The absolute bioavailability of the puerarin–SMEDDS sustained-release pellets was enhanced by approximately 2.6-fold compared with that of the puerarin tablet. The relative bioavailability (Frel) of the SMEDDS pellets was 259.7% compared with the tablet group. The results demonstrated that the puerarin–SMEDDS sustained-release pellets had a sustained-release effect, and could remarkably improve the oral bioavailability of puerarin.

Sustained-release alginate-chitosan pellets prepared by melt pelletization technique

Context: Alginate-chitosan pellets prepared by extrusion-spheronization technique exhibited fast drug dissolution.Objective: This study aimed to design sustained-release alginate pellets through rapid in situ matrix coacervation by chitosan during dissolution.Methods: Pellets made of alginate with chitosan and/or calcium acetate were prepared using solvent-free melt pelletization technique which prevented reaction between processing materials during agglomeration and allowed such reaction to occur only in dissolution phase.Results: Drug release was retarded in pH 2.2 medium when pellets were formulated with calcium acetate or chitosan till a change in medium pH to 6.8. The sustained-release characteristics of calcium alginate pellets were attributed to pellet dispersion and rapid cross-linking by soluble Ca2+ during dissolution. The slow drug release characteristics of alginate-chitosan pellets were attributed to polyelectrolyte complexation and pellet aggregation into swollen structures with reduced erosion. The drug release was, however, not retarded when both calcium acetate and chitosan coexisted in the same matrix as a result of chitosan shielding of Ca2+ to initiate alginate cross-linkages and rapid in situ solvation of calcium acetate induced fast pellet dispersion and chitosan losses from matrix.Conclusion: Similar to calcium alginate pellets, alginate-chitosan pellets demonstrated sustained drug release property though via different mechanisms. Combination of alginate, chitosan and calcium acetate in the same matrix nevertheless failed to retard drug release via complementary drug release pattern.

Response surface methodology and process optimization of sustained release pellets using Taguchi orthogonal array design and central composite design

Furosemide is a powerful diuretic and antihypertensive drug which has low bioavailability due to hepatic first pass metabolism and has a short half-life of 2 hours. To overcome the above drawback, the present study was carried out to formulate and evaluate sustained release (SR) pellets of furosemide for oral administration prepared by extrusion/spheronization. Drug Coat L-100 was used within the pellet core along with microcrystalline cellulose as the diluent and concentration of selected binder was optimized to be 1.2%. The formulation was prepared with drug to polymer ratio 1:3. It was optimized using Design of Experiments by employing a 32 central composite design that was used to systematically optimize the process parameters combined with response surface methodology. Dissolution studies were carried out with USP apparatus Type I (basket type) in both simulated gastric and intestinal pH. The statistical technique, i.e., the two-tailed paired t test and one-way ANOVA of in vitro data has proposed that there was very significant (P≤0.05) difference in dissolution profile of furosemide SR pellets when compared with pure drug and commercial product. Validation of the process optimization study indicated an extremely high degree of prognostic ability. The study effectively undertook the development of optimized process parameters of pelletization of furosemide pellets with tremendous SR characteristics.

Preparation of lovastatin matrix sustained-release pellets by extrusion-spheronization combined with microcrystal dispersion technique

The poorly water-soluble drug lovastatin (LVA) is an inhibitor of 3-hydroxy-3-methylglutarylcoenzyme A reductase and has a slow dissolution rate. In this study, a microcrystal dispersion (MCD) technique was used in the preparation of LVA to increase its dissolution rate and then combining with an extrusion-spheronization method, microcrystalline cellulose (MCC) matrix sustained-release pellets containing LVA-MCD were developed and characterized in vitro. Photomicrographs indicated that LVA-MCD existed as fine crystals, of which the mean particle size was reduced from 65.75 μm to 3.97 μm and the dried LVA-MCD powders released completely within 2 hours. SEM results during the release process showed that pellets possessed a matrix structure and after the dissolution test, this matrix structure became loose and porous. The release of LVA was fast and complete, and accumulated release by the optimal formulation was: 0.5 h (20.23 ± 3.40%), 2 h (56.87 ± 2.85%), 4 h (78.71 ± 3.42%), and 8 h (96.81 ± 3.30%). The 3 months accelerating test at 40°C and 75% RH demonstrated that drug release of pellets was not changed and drug degradation was less than 1%. Thus, a novel MCD process with MCC matrix was feasible and effective to get complete release without a lag time for the poorly water soluble drug, LVA, with high stability.

Preparation and in vitro–in vivo evaluation of none gastric resident dipyridamole (DIP) sustained-release pellets with enhanced bioavailability

The objective of this study was to develop none gastric resident sustained-release pellets loaded with dipyridamole with a high bioavailability. Two different kinds of core pellets, one containing citric acid as a pH-modifier (CAP) and, the other without pH-modifier (NCAP) were prepared by extrusion-spheronization and then coated with mixtures of enteric soluble and insoluble polymers (referred to as CAP 1 and NCAP 1) or insoluble polymer alone (referred to as CAP 2 and NCAP 2). The relative bioavailability of the sustained-release pellets was studied in fasted beagle dogs after oral administration using a commercially available immediate release tablet (IRT) as a reference. The in vitro release, in vivo absorption and in vitro–in vivo correlation were also evaluated. Results revealed that the plasma drug concentrations after administration of CAP 2, NCAP 1 and NCAP 2 were undetectable, indicating that the drug release was almost zero from the preparations throughout the gastro-intestinal tract. The C max, T max and AUC (0→24) of CAP 1 were 0.78 ± 0.23 (μg/ml), 3.80 ± 0.30 (h), and 6.74 ± 0.47 (μg/ml h), respectively. While the corresponding values were 2.23 ± 0.32 (μg/ml), 3.00 ± 0.44 (h) and 9.42 ± 0.69 (μg/ml h) for IRT. The relative bioavailability of CAP 1 was 71.55% compared with IRT. By combined incorporation of a pH-modifier into the core of pellets to modify the inner micro-environment and employing mixtures of enteric soluble and insoluble polymers as a retarding layer, drugs with high solubility in stomach and limited solubility in small intestine, such as DIP, could be successfully formulated as sustained release preparations with no pH-dependence in drug release and enhanced bioavailability.

Preparation and pharmacokinetics in beagle dogs of once-a-day tetramethylpyrazine phosphate sustained-release pellets

In this study, once-a-day tetramethylpyrazine phosphate (TMPP) sustained-release pellets were successfully prepared. The pellets cores were carried out in extrusion-spheronization machine and then coated in fluidized-bed. To optimize cumulative release profile, two different coating systems with the same the TMPP pellets cores were employed. The first coating system consisted of surlease, containing HPMC E5 (0.1% w/w), i.e., P1. The second coating system only consisted of surlease, i.e., P2. The two kinds of coating systems were both given coating levels in terms of weight gain of 10%. The resulted once-a-day TMPP sustained-release pellets (OTSP), the mixture of P1 and P2 with the weight proportion of 1:1, were filled in a capsule (150 mg TMPP/capsule). The relative bioavailability of OTSP was studied in six beagle dogs after oral administration using a commercial TMPP tablets as a reference. The Cmax and Tmax for OTSP and TMPP tablets were 213.06 ng/mL, 2.50 h and 3402.13 ng/mL, 0.33 h, respectively and the relative bioavailability of P3 was 97.18% compared with TMPP tablets. Based on the results, it was indicated that TMPP sustained-release pellets and TMPP conventional tablets were bioequivalent.