• Title/Summary/Keyword: drug release

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Drug-Release Behavior of Polymeric Prodrugs of Ibuprofen with PEG and Its Derivatives as Polymeric Carriers

  • Lee, Chao-Woo
    • Macromolecular Research
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    • v.12 no.1
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    • pp.71-77
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    • 2004
  • We have synthesized various types of poly(ethylene glycol) (PEG)-ibuprofen conjugates by nucleophilic substitution of bromo-terminated PEG with ibuprofen-Cs salt. The conversion of the terminal hydroxyl groups to bromo-termini was quantitative, as was the drug conjugation process, which suggests that the present synthetic method is very useful for the preparation of PEG-based prodrugs from pharmaceuticals having carboxyl functionalities. The drug-release behavior of the prodrugs was examined in both phosphate buffer (PBS, pH 7.4) and rat plasma. From the drug-release behavior in PBS, we determined that each prodrug has high storage stability. The drug-release rate was observed to be much faster in rat plasma than in buffer solution as a result of the acceleration effect provided by enzymes present in the plasma. The drug-release rate in rat plasma depends on the degree of molecular aggregation of the prodrugs, which can be changed effectively by the nature of their spacer groups or by the use of Pluronic as the polymer carrier.

Effects of Polymer-Drug Interactions on Drug Release from Sustained Release Tablets (서방정으로부터의 약물 용출에 대한 고분자-약물 상호작용의 영향)

  • Kim, Haeng-Ja;Lee, Seung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.26 no.2
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    • pp.119-124
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    • 1996
  • To develop oral controlled release dosage forms, ionic interactions between polymers and drugs were evaluated. Hydroxypropylmethyl cellulose and carboxymethylene were used as model nonionic and ionic polymers, respectively. 5-fluorouracil, propranolol-HCl and sodium salicylate were selected as model nonionic, cationic and anionic, respectively. Polymer-drug mixtures were compressed into tablets and drug release kinetics from these tablets were determined. Drug release from the tablets made of the nonionic polymer was not affected by the charge of drugs, rather, was regulated by the solubility of drugs in different pH releasing media. However, drug release kinetics were significantly affected when drug-polymer ionic interactions exist. Enhanced drug release was observed from anionic drug-anionic polymer tablets due to ionic repulsion, whereas drug release was retarded in cationic drug-anionic polymer tablets owing to ionic attractive force. Therefore, the results suggested that the polymer-drug interactions are important factors in designing controlled release dosage forms.

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Study on Preparation and Drug Release of Sulconazole Nitrate Gels (질산술코나졸겔의 제조 및 약물방출에 관한 연구)

  • Hyun, Jong-Mok;Kim, Kyung-Kook;Jee, Ung-Kil
    • Journal of Pharmaceutical Investigation
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    • v.26 no.4
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    • pp.263-271
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    • 1996
  • Sulconazole nitrate(SCN), an imidazole derivative which has been effective in the treatment of dermatophytosis, tinea versicolor and candidiasis, was formulated as a gel containing drug, poloxamer 407, ethanol and propylene glycol. The resulting SCN gels were evaluated with respect to their viscosity, drug release rate, skin permeation rate. The apparent viscosity of SCN gel increased in proportion to poloxamer 407, drug and propylene glycol concentration. In case ethanol was added, the apparent viscosity decreased. The drug release rate of SCN gel increased in proportion to temperature and ethanol concentration. But the drug release rate decreased as the concentration of poloxamer 407 increased. The increase of drug concentration induced nonlinear increase of drug release rate. When propylene glycol was added at the level of 10%, the drug release rate increased but from 15% it decreased. The skin permeation rate decreased in high concentration of poloxamer 407. The skin permeation rate of SCN gel containing 15% ethanol increased about twice than that of gel without ethanol. The increase of drug concentration induced nonlinear increase of skin permeation rate. When propylene glycol was added at the level of 10%, the skin permeation rate increased but from 15% it decreased.

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Drug Release Characteristics of Biodegradable Polymers for Stent Coating (스텐트 코팅용 생분해성 고분자의 약물 방출 특성)

  • 강혜수;김진설;김동운;강병철;이봉희;김범수
    • KSBB Journal
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    • v.18 no.2
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    • pp.107-110
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    • 2003
  • Biodegradable polymers, poly(lactic-co-glycolic acid) (PLGA), poly(3-hydroxybutyrate) (PHB), and medium chain length polyhydroxyalkanoates (MCL-PHA) containing rose bengal (model drug) were coated onto the surface of stainless steel (stent materials) and their in vitro release characteristics were investigated. Drug release increased with; decreasing PLGA concentration, increasing rose bengal concentration, and Increasing dip-coating duration. The order of drug release from the polymer coating was: PHB > PLGA > MCL-PHA. These results suggest that drug release can be controlled by: changing the concentration and type of polymer, the drug concentration, and the dip-coating duration.

Formulation Design of Sustained-Release Matrix Tablets Containing 4-Aminopyridine (유드라짓과 알긴산 나트륨 매트릭스를 이용한 4-Aminopyridine의 서방성 제제설계)

  • Kim, Jeong-Soo;Kim, Dong-Woo;Lee, Gye-Won;Jee, Ung-Kil
    • Journal of Pharmaceutical Investigation
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    • v.35 no.6
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    • pp.453-460
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    • 2005
  • 4-Aminopyridine (AP) is a potassium channel blocker used in the treatment of neurological disorders such as multiple sclerosis and Alzheimer disease. AP‘s window of therapeutic effect appears to correlate with its plasma halflife (3.5 hours). It demonstrates pH-dependent solubility because of a weakly basic drug. In addition, the resulting release from conventional matrix tablets decreases with increasing pH-milieu of the gastrointestinal tract. The aim of this study is to design sustained release matrix tablet containing AP, overcoming this problem. $Eudragit^{\circledR}$ L 100 (EuL) and sodium alginate were used in an effort to achieve pH independent drug release. The effect of sodium alginate and EuL on drug release from matrix tablet was investigated. The drug release behavior from the different tablets was analyzed by $t_{20%},\;t_{40%},\;t_{60%}$, The exponential diffusion coefficient n, kinetic constant K were calculated according to the Korsmeyer-Peppas equation. The drug release from matrix tablets prepared with sodium alginate was decreased with increasing the content of sodium alginate in pH 7.4 while there is no significant difference in pH 1.2. The exponent n values were determined to be approximately 0.5 and 0.8 respectively, in both pH 1.2 and 7.4. These values indicate diffusion-based anomalous mechanism and erosion-based anomalous mechanism, respectively. The drug release from sodium alginate matrix tablets prepared with solid dispersion of EuL containing drug showed a slow drug release in an acidic medium and a more fast drug release in phosphate medium, compared with sodium alginate matrix tablets prepared with physical mixture. These results may be attributed to the gel forming ability of sodium alginate and pH dependent solubility of EuL. Therefore, sustained-release AP matrix tablets using sodium alginate and EuL were successfully prepared.

Prenatal effect of pyrantel pamoate on several hematological parameter of offspring in mice

  • Abdulwahab.A.Noorwall;Ghazi M. Al-Hachim;Award -Omar
    • Archives of Pharmacal Research
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    • v.9 no.2
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    • pp.87-91
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    • 1986
  • In attempt to develop a drug delivery system using serum albumin microspheres, bovine serum albumin microspheres containing antitumar agent. Cytarabine, were prepared. The shape, surface characteristics, size distribution, behavior of in vivo distribution, drug release behavior, and degradation of albumin microsphers in animal liver issue homogenate and proteolytic enzyme were investigated. The shape of albumin microspheres was spherical and the surface was smooth and compact. The size distribution of the albumin microspheres was effected by dispertion forces during emulsification and albumin concentration. Distribution of albumin microspheres after imtravenous administration in rabbit was achieved immediately. In vitro, albumin microsphere matrix was so hard that it retained most of cytarabine except initial burst during the first 10 minutes, and the level of drug release during the initial burst was affected by heating temperature, drug/albumin microsphere matrix was so hard that it retained most of cytarabine except initial burst during the first 10 minutes, and the level of drug release during the initial burst was affected by heating temperature, drug/albumin concentration ratio and size distribution. After drug release test, the morphology of albumin microspheres was not changed. Albumin microsphere matrix was degraded by the animal liver issue homogenate and proteolytic enzyme. The degree of degradation was affected by heating temperature.

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Cross-Linked Starch Microspheres: Effect of Cross-Linking Condition on the Microsphere Characteristics

  • Atyabi, Fatemeh;Manoochehri, Saeed;Moghadam, Shadi H.;Dinarvand, Rassoul
    • Archives of Pharmacal Research
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    • v.29 no.12
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    • pp.1179-1186
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    • 2006
  • Cross-linked starch microspheres were prepared using different kinds of cross-linking agents. The influence of several parameters on morphology, size, swelling ratio and drug release rate from these microspheres were evaluated. These parameters included cross-linker type, concentration and the duration of cross-linking reaction. Microspheres cross-linked with glutaraldehyde had smooth surface compared with those prepared with epichlorhydrine or formaldehyde. The particle size increased with increasing the cross-linking time and increasing the drug loading. Swelling ratio of the particles was a function of cross-linker type but not the concentration or time of cross-linking. Drug release from starch microspheres was measured in phosphate buffer and also in phosphate buffer containing a-amylase. Results showed that microspheres cross-linked with epichlorhydrine released all their drug content in the first 30 minutes. However, cross-linking of the starch microspheres with glutaraldehyde or formaldehyde decreased drug release rate. SEM and drug release studies showed that cross-linked starch microspheres were susceptible to the enzymatic degradation under the influence of alpha-amylase. Changing the enzyme concentration from 5000 to 10,000 IU/L, increased drug release rate but higher concentration of enzyme (20,000 IU/L) caused no more acceleration.

A Formulation Study for the Controled Release Rate of Diltiazem. HCl using the Multiple Drug Release System (다중약물방출시스템을 이용한 염산딜티아젬의 방출속도 조절에 관한 연구)

  • Kim, Hak-Hyung;Oh, Jin-Hwan;Han, Kun
    • Journal of Pharmaceutical Investigation
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    • v.35 no.3
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    • pp.157-163
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    • 2005
  • The pellets with multiple drug release system (MDRS) of Diltiazem. HCl which consist of immediate drug release layer, drug reservoir layer and controlled release rate membrane, were prepared by using CF-Coater. As main factors for more effective MDRS of Diltiazem. HCl, ethylcellulose was used for the controlling drug release rate, and diethylphthalate was used for plasticizer, respectively. In vitro evaluation study was performed by comparative dissolution test between our test MDRS and reference Diltiazem. HCl preparation. The physical tests were performed using FT-IR and SEM. In vivo evaluation was also performed by observing the behavior of a plasma drug concentration after oral administration. The bioavailability was determined by analyzing the blood sample after oral administration to healthy, male volunteers once a day. As a result, there were no significant differences in bioequivalence parameters $(AUC_{\infty},\;C_{max},\;t_{1/2})$ between two systems. It might be concluded that our MDRS of Diltiazem. HCl could be an alternative delivery system to reference drug preparation.

pH-Dependent Drug Release from Polymethacrylic Acid Hydrogel Matrix (Polymethacrylic Acid 하이드로겔 매트릭스로부터의 pH 의존성 약물 방출)

  • Kim, Kyung-Chung;Kim, Kil-Soo;Lee, Seung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.19 no.4
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    • pp.179-183
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    • 1989
  • Drug release experiments were performed based on pH-sensitive swelling behaviors of polymethacrylic acid. 5-Fluorouracil as a nonionic model drug revealed release patterns depending solely on pH-dependent swelling kinetics of polymethacrylic acid. In contrast, release of propranolol hydrochloride as a cationic model drug was significantly affected by ionic drug-polymer interaction as well as the swelling kinetics. Accordingly, a zero-order release pattern was obtained at pH 7, which was distinguished from the general matrix type drug release pattern.

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Swelling Controlled Drug Release from Acrylamide-Styrene Copolymer Hydrogels (Acrylamide-Styrene Copolymer 하이드로겔로부터의 수팽윤 속도조절에 의한 약물 방출)

  • Kim, Min-Kyoung;Lee, Seung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.19 no.4
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    • pp.173-178
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    • 1989
  • Drug release rates from copolymer hydrogels were controlled by their hydrophilic-hydrophobic balances. As a model copolymer hydrogel, poly(acrylamide-co-styrene) was synthesized at different monomer composition. Release mechanisms of propranolol-HCI from the copolymer matrices were investisated. Swelling rates of the copolymer hydrogels retarded as their hydrophobicity increased. Swelling kinetics of the copolymer hydrogels regulated drug release rates via polymer relaxation controlled release mechanisms. Zero order drug release could thus be achieved within certain periods.

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