• Journal of Pharmaceutical Investigation
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• v.31 no.1
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• pp.19-25
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• 2001

The purpose of this study was to use a ternary polymeric matrix system for high drug loading of a highly soluble drug for controlled release delivery. The controlled drug delivery of diltiazem HCl (solubility > 50% in water at $25^{\circ}C$) with high loading dose (the final loading dose of drug was 34%) from a ternary polymeric matrix (gelatin, pectin, HPMC) was successfully accomplished. This simple monolithic system with 240 mg drug loading provided near zero-order release over a 24 hour-period by which time the system was completely dissolved. The release kinetics of diltiazem HCl tablet with high loading dose from the designed ternary polymeric system was dependent on the ratios of HPMC : pectin binary mixture. The release rate increased as pectin : HPMC ratio were increased. Swelling behavior of the ternary system and the ionic interaction of formulation components with cationic diltiazem molecule appear to control drug diffusion and the release kinetics. Comparable release profiles between commercial product and the designed system were obtained. The binding study between gelatin with diltiazem HCl showed the presence of two binding sites for drug interaction with subsequent controlled diffusion upon swelling. This designed delivery system is easy to manufacture and drug release behavior is highly reproducible and offers advantages over the existing commercial product.

• Journal of Biomedical Engineering Research
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• v.41 no.1
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• pp.62-66
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• 2020

Controlled drug release is important for effective treatment of cancer. Poly(DL-lactide-co-glycolide) acid (PLGA) is a Food and Drug Administration (FDA) approved polymer and have been extensively studied as drug delivery carriers with biodegradable and biocompatible properties. However, PLGA drug delivery carriers are limited due to the initial burst release of drug. Certain drugs require an early rapid release, but in many cases the initial rapid release can be inefficient, reducing therapeutic effects and also increasing side effects. Therefore, sustained release is important for effective treatment. Poly Lactic Acid stereo complex (PLA SC) is resistant to hydrolysis and has high stability in aqueous solutions. Therefore, in this work, PLGA based discoidal polymeric particles are modified by Poly Lactic Acid stereocomplex (PLAsc DPPs). PLAsc DPPs are 3 ㎛ in diameter, also showing a relatively sustained release profile. Fluorescein 5(6)-isothiocyanate (FITC) released from PLAsc DPPs was continuously observed until 38 days, which showed the initial release of FITC from PLAsc DPPs was about 3.9-fold reduced as compared to PLGA based DPPs at 1 hour.

• Archives of Pharmacal Research
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• v.29 no.7
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• pp.598-604
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• 2006

In many conventional drug delivery systems in vogue, failure to deliver efficient drug delivery at the target site/organs; is evident as a result, less efficacious pharmacological response is elicited. Microspheres can be derived a remedial measure which can improve site-specific drug delivery to a considerable extent. As an application, Lung-targeting Ofloxacin-loaded gelatin microspheres (GLOME) were prepared by water in oil emulsion method. The Central Composite Design (CCD) was used to optimize the process of preparation, the appearance and size distribution were examined by scanning electron microscopy, the aspects such as in vitro release characteristics, stability, drug loading, loading efficiency, pharmacokinetics and tissue distribution in albino mice were studied. The experimental results showed that the microspheres in the range of $0.32-22\;{\mu}m$. The drug loading and loading efficiency were 61.05 and 91.55% respectively. The in vitro release profile of the microspheres matched the korsmeyer’s peppas release pattern, and release at 1h was 42%, while for the original drug, ofloxacin under the same conditions 90.02% released in the first half an hour. After i.v. administration (15 min), the drug concentration of microspheres group in lung in albino mice was $1048\;{\mu}g/g$, while that of controlled group was $6.77\;{\mu}g/g$. GLOME found to release the drug to a maximum extent in the target tissue, lungs.

• Macromolecular Research
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• v.16 no.1
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• pp.45-50
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• 2008

This study examined the swelling behavior and in vitro release of a model drug, tetracycline-HCl, from alginate and alginate-polyaspartate (Alg-PASP) composite gel beads. The alginate and Alg-PASP composite beads were prepared using an ionic crosslinking method with aqueous $Ca^{2+}$. Their microporous morphology was observed by scanning electron microscopy. The swelling ratio of the beads in different media varied according to their composition, cross-linking density ($Ca^{2+}$ concentration), and pH of the aqueous medium. The in vitro release experiment of the tetracycline-HCl encapsulated beads in different media suggests that the release of the drug is governed mainly by the swelling properties of the polymer network. The presence of PASP was found to significantly influence the swelling properties and drug release profile.

• Journal of Pharmaceutical Investigation
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• v.38 no.1
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• pp.63-72
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• 2008

Meloxicam-loaded microspheres were prepared with poly(D,L-lactic acid)(PLA) by a solvent-emulsion evaporation method. The morphology, particle size, drug loading capacity, drug entrapment efficiency (EE) and release patterns of drug were investigated in vitro. Various batches of micro spheres with different size and drug content were obtained by changing the ratio of meloxicam to $PLA^{\circ}{\AE}s$ with different molecular weight, PLA concentration in the dispersed phase and stirring rate. Meloxicam crystals on microsphere surface, which were released rapidly and could act as a loading dose, were observed with increasing drug content. The release rate was increased with increase in drug contents and decrease in the molecular weight of PLA. Microspheres prepared with smaller molecular weight produced faster drug release rate. The release rate of meloxicam for long-acting injectable delivery system in vitro, which would aid in predicting in vivo release profile, could be controlled by properly optimizing various factors affecting characteristics of microspheres. Blood concentration-time profile of meloxicam after intramuscular injection of meloxicam-loaded microspheres in rabbits showed possibility of long term application of this system in clinical settings.

• Archives of Pharmacal Research
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• v.28 no.9
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• pp.1092-1096
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• 2005

Huperzine A-loaded microspheres composed of poly(D,L-lactide-co-glycolide) were prepared by an O/w emulsion solvent evaporation method. The characterization of the microspheres such as drug loading, size, shape and release profile was described. The in vitro release in the initial 7 days was nearly linear with $10\%$ released per day. Thereafter drug release rate became slow gradually and about $90\%$ drug released at day 21. The in vitro release rate determined by dialysis bag method had a good correlation with the in vivo release rate. Huperzine A aqueous solution was intramuscularly injected (i.m.) at 0.4mg/kg and microspheres were intra­muscularly injected at 8.4 mg eq huperzine A/kg in rats. The maxium plasma concentration $(C_{max})$ after i.m. microspheres was only $32\%$ of that after i.m. solution. Drug in plasma could be detectd until day 14 and about $5\%$ of administered dose was residued at the injection site at day 14. The relative bioavailability of huperzine A microspheres over a period of 14 days was $94.7\%$. Inhibition of acyecholinesterase activity (AchE) in rat's cortex, hippocampus and striatum could sustain for about 14 days. In conclusion, huperzine A-loaded microspheres possessed a prolonged and complete drug release with significant inhibition of AchE for 2 weeks in rats.

• Journal of Pharmaceutical Investigation
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• v.22 no.2
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• pp.133-137
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• 1992

A novel oral controlled release tablet which may offer more uniform drug level in the body than simple zero-order was developed. The tablet is composed of three layers; outer film layer, middle part compression-coated hydroxypropylmethylcellulose (HPMC) matrix layer, and inner core layer. Each layer contains nicardipine HCl as a model drug. In vitro dissolution test showed that the tablet released the drug in clear three steps; a rapid initial release, followed by a constant rate of release, and then a second phase of fast release of drug. The dissolution characteristics could be modified easily by changing the grade of HPMC, thickness of matrix layer, content of methylcellulose in matrix layer, content of active ingredient in each layer. The pH of dissolution medium did not affect the release profile. This three-step release system is expected to raise the blood concentration rapidly to effective level and to maintain effective blood level longer than simple slow-release systems.

• Macromolecular Research
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• v.14 no.4
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• pp.461-465
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• 2006

Two types of injectable system using thermosensitive chitosan (chitosan-g-NIPAAm), hydrogel and microparticles (MPs)-embedded hydrogel were developed as drug carriers for controlled release and their pharmaceutical potentials were investigated. 5-Fluorouracil (5-FU)-loaded, biodegradable PLGA MPs were prepared by a double emulsion method and then simply mixed with an aqueous solution of thermosensitive chitosan at room temperature. All 5-FU release rates from the hydrogel matrix were faster than bovine serum albumin (BSA), possibly due to the difference in the molecular weight of the drugs. The 5-FU release profile from MPs-embedded hydrogel was shown to reduce the burst effect and exhibit nearly zero-order release behavior from the beginning of each initial stage. Thus, these MPs-embedded hydrogels, as well as thermosensitive chitosan hydrogel, have promising potential as an injectable drug carrier for pharmaceutical applications.

• Journal of Pharmaceutical Investigation
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• v.36 no.1
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• pp.39-44
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• 2006

Tamsulosin or a salt thereof such as its hydrochloride salt has been known to have an adrenaline ${\alpha}$ receptor blocking action for urethra and prostate areas. It has been widely used as a drug which lowers the prostate pressure and improves urinary disturbance accompanied by prostate-grand enlargement, thus for the treatment of prostatic hyperplasia. To avoid dose-dependent side effects of tamsulosin upon oral administration, the development of sustained-release delivery system is essentially required, that can maintain therapeutic drug levels for a longer period of time. The aim of this study was therefore to formulate sustained-release tamsulosin granules and assess their formulation variables. We designed entric coated sustained-release tamsulosin granules for this purpose. Nano-pores in the outer controlled release membrane were needed in order to obtain initial tamsulosin release even in an acidic environment such as gastric region. In our sustained release osmotic granule system, hydroxypropylmethylcellulose in a drug-containing layer was used as a rate controller. The drug-containing granules were coated with hydroxypropylmethylcellulose phthalate (HPMCP) and Eudragit, along with glycerol triacetate as an aqueous nano-pore former. The release of tamsulosin depended heavily on the type of Eudragit such as RS, RL, NE 30D, used in the formulation of controlled release layer. These results obtained clearly suggest that the sustained-release oral delivery system for tamsulosin could be designed with satisfying drug release profile approved by the Korean Food and Drug Administration.

• Journal of Pharmaceutical Investigation
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• v.32 no.2
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• pp.103-106
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• 2002

A method that describes the determination of the in vitro release of ketoprofen from gels was suggested. The experimental system of the method consists of a Franz diffusion cell, which contains a pH 7.4 phosphate buffer as a receptor medium, and a $70\;{\mu}m$ mesh woven nylon membrane as a diffusion barrier. Under the given condition of the system, the diffusion of ketoprofen across the membrane was rapid enough that the apparent release profile of ketoprofen obtained from the present method could represent the release of the drug from gel preparations. The release of ketoprofen in the present method was reproducible, and the rate increased in proportion to the concentration of ketoprofen in the gel. These suggest that the present method is applicable to the quality evaluation of gel preparations containing ketoprofen.