• Advances in Traditional Medicine
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• v.7 no.1
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• pp.51-64
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• 2007

Mucus is an aqueous gel complex with a constitution of about 95% water, high molecular weight glycoprotein (mucin), lipid, salts etc. Mucus appears to represent a significant barrier to the absorption of some compounds. Natural mucoadhesive agent was isolated and purified from the aqueous extract of the seeds of prosopis pallida (PP). Formulated tablet with the isolated material by wet granulation method. Some natural edible substances are in consideration for candidates as mucoadhesive agents to claim more effective controlled drug delivery as an alternative to the currently used synthetic mucoadhesive polymers. Subjected the materials obtained from natural source i.e. PP and standard synthetic substance, sodium carboxymethyl cellulose for evaluation of mucoadhesive property by various in vitro and in vivo methods. Through standard dissolution test and a model developed with rabbit, evaluated in vitro controlled release and bioadhesive property of theophylline formulation. Mucoadhesive agent obtained from PP showed good mucoadhesive potential in the demonstrated in vitro and in viνo models. The results suggest that the mucoadhesive agent showed controlled release properties by their application, substantially. In order to assess the gastrointestinal transit time in vivo, a radio opaque X-ray study performed in healthy rabbit testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of theophylline determined by the HPLC method and those allowed correlations to the in vitro mucoadhesive study results. Better correlation found between the results in different models. PP may acts as a better natural mucoadhesive agent in the extended drug delivery system.

• Journal of Pharmaceutical Investigation
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• v.41 no.4
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• pp.217-225
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• 2011

The aim of this work was to prepare porous osmotic pump tablets for controlled delivery of Aceclofenac. Aceclofenac solid dispersion was prepared to improve the solubility by using the drug - carrier (Mannitol) ratio of 1:1. The osmotic pump tablets were prepared using the solid dispersed product of Aceclofenac. The formulation contains potassium chloride as osmotic agent, cellulose acetate as semipermeable membrane, poly ethylene glycol (PEG 4000) as pore former and sodium lauryl sulphate (SLS) as solubility enhancer. The formulations were designed by the general factors such as osmotic agent and pore former. All formulations were evaluated for various physical parameters and, the in vitro release studies were conducted as per USP. The drug release kinetic studies such as zero order, first order, and Higuchi and Korsmeyer peppas were determined and compared. All the formulations gave more controlled release compared to the marketed tablet studied. Numerical optimization techniques were applied to found out the best formulation by considering the parameter of in vitro drug release kinetics and dissolution profile standards. It was concluded that the porous osmotic pump tablets (F7) composed of Aceclofenac solid dispersion/Potassium chloride/Lactose/Sodium lauryl sulphate/Magnesium Stearate (400/40/95/10/5, mg/tab) and coating composition with Cellulose acetate/ PEG 4000 (60/40 %w/w) is the most satisfactory formulation. The porous osmotic pump tablets provide prolonged, controlled, and gastrointestinal environment-independent drug release.

• The Korean Journal of Pharmacology
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• v.29 no.2
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• pp.183-188
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• 1993

Effects of glucose on the catecholamine release from the hypothalamic fragments in vitro were studied. Basal release of catecholamines was inversely related to the concentrations $(5{\sim}30\;mM)$ of glucose in the incubation medium. Glucose did not affect the 30 mM $K{^+}-stimulated$ release of catecholamine. In the presence of tetrodotoxin $(10\;{\mu}M)$, the inhibitory effect of glucose on the basal release of catecholamines was largely persisted, but the inhibitory effect of 30 mM glucose on dopamine release was largerly blocked. In the presence of both tetrodotoxin $(10\;{\mu}M)$ and desipramine $(3\;{\mu}M)$, glucose failed to affect the basal catecholamine release. The results suggest that glucose modulates the catecholamine release through a direct action on the catecholaminergic nerve terminals, as well as through a trans-synaptical action. The glucose-modulation of the catecholamine release may explain, at least in part, the diabetes-induced changes in the hypothalamic catecholamine metabolism.

• Biomolecules & Therapeutics
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• v.22 no.2
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• pp.161-165
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• 2014

The main purpose of this study was to develop a novel, in situ gel system for sustained delivery of ranitidine hydrochloride. Ranitidine in situ gels at 0.2%, 0.5%, and 1.0% gellan gum concentration (w/v) were prepared, respectively, and characterized in terms of preparation, viscosity and in vitro release. The viscosity of the gellan gum formulations in solution increased with increasing concentrations of gellan gum. In vitro study showed that the release of ranitidine from these gels was characterized by an initial phase of high release (burst effect) and translated to the second phase of moderate release. Single photon emission computing tomography technique was used to evaluate the stomach residence time of gel containing $^{99m}Tc$ tracer. The animal experiment suggested in situ gel had feasibility of forming gels in stomach and sustained the ranitidine release from the gels over the period of at least 8 h. In conclusion, the in situ gel system is a promising approach for the oral delivery of ranitidine for the therapeutic effects improvement.

• Journal of Pharmaceutical Investigation
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• v.26 no.4
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• pp.273-280
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• 1996

Chondroitin sulfate/gelatin microspheres containing dexamethasone 21-acetate were prepared by complex coacervation method and their release patterns were examined in vitro. Microspheres prepared with a small amount of crosslinking agent had smooth surface and few pores, but those with a large amount of crosslinking agent were more porous and less spherical. In vitro release patterns were varied by changing polymer/drug weight ratio and amount of crosslinking agent. The release rate of dexamethasone 21-acetate in the presence of collagenase was faster than that in the absence of collagenase. Anti-inflammatory effect of dexamethasone 21-acetate microspheres was more efficient than that of dexamethasone 21-acetate solution in carrageenan-induced arthritis in the rat. On the basis of the above results, we might expect the degradation and drug release rate of these microspheres to be regulated by the degree of crosslinking and the level of enzymes. In patients with severe rheumatoid arthritis who have high concentration of collagenase, more drug would be released from the microspheres. An intra-articular injection therapy of rheumatoid arthritis with desired release kinetics could be developed to enhance patient compliance and therapeutic index.

• Journal of Pharmaceutical Investigation
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• v.26 no.2
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• pp.137-144
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• 1996

The study was carried out for the preparation and evaluation of a buoyant hydrogel matrix (BHM), which is buoyant in a neutral or in pH 2.0 buffer solution, by the aspects of buoyancy, swelling, and drug release. Physical mixtures of HPC and CP in various molar ratio were employed as a mucoadhesive polymer which swells and controls the rate of drug release. Anhydrous citric acid and sodium bicarbonate in the molar ratio of 1:3 were employed as effervescing agents which provide a buoyancy for the mucoadhesive polymeric matrix. The buoyancy in vitro was expressed as both floating time$(T_{fl})$ and surfing time$(T_{sf})$, which are the time required for floating from the bottom to the surface of the medium and the time to keep the floated state at the surface of medium during release studies, respectively. A close relationship was observed between the buoyancy and the amount of effervescing agent added. $T_{fl}$ of the buoyant hydrogel matrices were decreased to about 10 seconds linearly with increasing the amount of effervescing agent in the range of 5 to 15%. $T_{sf}$ of the buoyant hydrogel matrices were varied from 1 to 3 hr depending on the amount of effervescing agent. The swelling was observed by changes in diameter of the buoyant hydrogel matrices in distilled water or acidic buffer solution, resulted in dependences on pH and the amount of effervescing agents. The release of hydrochlorothiazide from the buoyant hydrogel matrices were followed by apparent zero-order kinetics, while the buoyant hydrogel matrices were floated at the surface and maintaining their swollen shapes.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.20 no.3
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• pp.51-62
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• 2007

Objective : The aim of this study is to assess the effect of Schizandrae Fructus on melanin synthesis inhibition and whitening effect. Methods : We assessed inhibitory effects of Schizandrae Fructus on melanin-release from B16F10, on melanin production in B16F10, on mushroom tyrosinase activity in vitro, on tyrosinase activity in B16F10 and effect of Schizandrae Fructus on the expression tyrosinase, TRP-1, TRP-2, PKA, ERK-1 ERK-2, AKT-1, MITF in B16F10. Results and Conclusion : 1. Schizandrae Fructus inhibited melanin-release, melanin production in B16F10. 2. Schizandrae Fructus inhibited tyrosinase activity in vitro and in B16F10. 3. Schizandrae Fructus suppressed the expression of tyrosinase, TRP-1, TRP-2, PKA, ERK-2 in B16F10.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.209-215
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• 2015

Objectives: The aim of this study was to evaluate the fluoride release of conventional glass ionomer cements (GICs) and resin-modified GICs. Materials and Methods: The cements were grouped as follows: G1 (Vidrion R, SS White), G2 (Vitro Fil, DFL), G3 (Vitro Molar, DFL), G4 (Bioglass R, Biodinamica), and G5 (Ketac Fil, 3M ESPE), as conventional GICs, and G6 (Vitremer, 3M ESPE), G7 (Vitro Fil LC, DFL), and G8 (Resiglass, Biodinamica) as resin-modified GICs. Six specimens (8.60 mm in diameter; 1.65 mm in thickness) of each material were prepared using a stainless steel mold. The specimens were immersed in a demineralizing solution (pH 4.3) for 6 hr and a remineralizing solution (pH 7.0) for 18 hr a day. The fluoride ions were measured for 15 days. Analysis of variance (ANOVA) and Tukey's test with 5% significance were applied. Results: The highest amounts of fluoride release were found during the first 24 hr for all cements, decreasing abruptly on day 2, and reaching gradually decreasing levels on day 7. Based on these results, the decreasing scale of fluoride release was as follows: G2 > G3 > G8 = G4 = G7 > G6 = G1 > G5 (p < 0.05). Conclusions: There were wide variations among the materials in terms of the cumulative amount of fluoride ion released, and the amount of fluoride release could not be attributed to the category of cement, that is, conventional GICs or resin-modified GICs.

• YAKHAK HOEJI
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• v.34 no.3
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• pp.161-165
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• 1990

An automated, simple, and reliable method was developed for determining in vitro drug release rate from transdermal delivery dosage forms. The patch is held in position in the heating block by sandwiching it between the middle plate and the bottom plate of diffusion cell. The dissolution profile of the commercially available transdermal scopolamine patch was determined over a 72-h period, and the results were compared with those obtained with other methods; paddle-over-disk method, reciprocating method, and diffusion cell method. It was demonstrated that the flow-through method is equivalent in terms of release rate profile and accumulated released drug amount over the lifetime of the dosage form tested. Also this method is simple, reliable and reproducible. Therefore, this technique can be used in a quality control for assuring product uniformity.

• Journal of Pharmaceutical Investigation
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• v.39 no.1
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• pp.7-12
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• 2009

A novel polymeric tablet of Tinidazole was formulated to treat Helicobacter pylori and Giardia lambria more efficiently, It was possible to reduce hepatotoxicity by controlling the release of Tinidazole after peroral administration. A gastric retentive formulation made of naturally occurring carbohydrate polymers and containing Tinidazole was tested in vitro for swelling and dissolution characteristics. Tinidazole tablets containing various concentration of either PEO or HPMC were prepared by the wet granulation method. In vitro release of Tinidazole at pH 1.2 and pH 6.8 buffer solutions was observed at $37^{\circ}C$ by using a KP dissolution method and an UV (313 nm) spectrophotometer. Compared to a commercial Tinidazole tablet, in vitro release of Tinidazole at both pH 1.2 and pH 6.8 buffer solutions significantly decreased as the concentration of PEO or HPMC in the tablet increased up. And the gastric retentive formulation hydrated and swelled back to about 50% of its original size in 30 min. Thus, it was possible to control the release of Tinidazole by changing the content of PEO or HPMC in the tablet, thereby manipulating the release rate and the retention of Tinidazole.