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Ciftci K, Hincal AA, Kas HS, Ercan TM, Sungur A, Guven O, Ruacan S. Solid tumor chemotherapy and in vivo distribution of fluorouracil following administration in poly(L-lactic acid) microspheres. Pharm Dev Technol 1997; 2:151-60. [PMID: 9552441 DOI: 10.3109/10837459709022620] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The physicochemical properties and in vivo distribution of poly(L-lactide) (L-PLA) microspheres containing 5-fluorouracil (5-FU) prepared by a solvent evaporation method were evaluated for potential use in the treatment of liver cancers. Two different molecular weight polymers of L-PLA [L-PLA1 (152,500 Da) and L-PLA2 (52,000 Da)] were used to prepare 5-FU-loaded microspheres. The mean particle size of the microspheres was 3-6 microns, and there was a direct relationship between the mean particle size and the molecular weight of the polymers. The drug release behavior from microspheres exhibited a diffusion mechanism in different dissolution media, with the molecular weight of the polymer being a major factor in controlling the drug release and degradation rates. Following intravenous injection of 99mTc-labeled L-PLA microspheres, with or without 5-FU, or free 5-FU into mice, L-PLA2 microspheres localized mainly in the liver. The disappearance rate of radioactivity from the tissue was very slow in comparison to that of free 5-FU. The results were confirmed by histological examination of liver tissue following administration of fluorescein particles. In addition, growth of a human liver tumor as first transplant generation under the renal capsule of immunocompetent rats and antitumor activity of L-PLA2 microspheres were investigated. Histological examination by optical microscopy showed that there was no neoplastic tissue of the kidney or in other tissues examined after treatment.
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Affiliation(s)
- K Ciftci
- Faculty of Pharmacy, Department of Pharmaceutical Technology, University of Hacettepe, Ankara, Turkey
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102
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Affiliation(s)
- U V Banakar
- St. Louis College of Pharmacy, MO 63110, USA
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103
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Rothen-Weinhold A, Gurny R. Controlled and/or prolonged parental delivery of peptides from the hypothalmic pituitary axis. Eur J Pharm Biopharm 1997. [DOI: 10.1016/s0939-6411(96)00030-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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104
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Bhardwaj R, Blanchard J. In vitro evaluation of Poly(d,l-lactide-co-glycolide) polymer-based implants containing the α-melanocyte stimulating hormone analog, Melanotan-I. J Control Release 1997. [DOI: 10.1016/s0168-3659(96)01544-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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105
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Hudon E, Rondeau JJ, Lenaerts V, Würthrich P, Boutignon F, Deghenghi R, Marleau S, Yamaguchi N, Adam A, Ong H. Radioimmunoassay of meterelin and pharmacokinetics after single injection and implant administration in dogs. J Pharm Sci 1997; 86:172-8. [PMID: 9040091 DOI: 10.1021/js960332v] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A sensitive and specific radioimmunoassay for a novel luteinizing-hormone-releasing-hormone (LHRH) agonist, [2-Me-D-Trp6, DesGly10]LHRH ethylamide (meterelin), was developed for documenting the pharmacokinetic parameters of this peptide following its intravenous (iv) and subcutaneous (sc) administration in dogs. The assay was also used for monitoring meterelin in plasma following its release from d,l-lactide-glycolide implants in the same species. Rabbit antisera generated against [DespyroGlu1] meterelin and conjugated to bovine serum albumin with glutaraldehyde showed high specificity, whereas crossreactivity to LHRH and its fragments and to analogs with substitutions at residues 6 and 10 was found insignificant. The assay was validated in terms of accuracy (recovery range, 94.0-105.4%), in terms of precision (intra- and interassay variations of 10.0-12.4% and 8.6-11.3%, respectively), and in terms of sensitivity (minimum detectable dose of 2.7 pg/assay). Following iv acute administration, a biexponential decline of plasma meterelin levels was observed, with distribution and elimination half-lives of 5.9 +/- 2.5 and 106 +/- 22 min, respectively. After sc acute administration, the elimination half-life was in the range of 103 to 173 min. The systemic clearance (CLT) ranged from 1.6 to 2.6 mL/min/kg, and the volume of distribution at steady state (Vdss) varied from 285 to 438 mL/kg. The elimination half-life (T1/2 beta), Vdss, and ClT were not significantly different after both routes of administration over the 1-100-microgram/kg dose range of peptide studied. Castrate levels of testosterone were attained 10 days after sc administration of the implant, lasted for up to 247 days, and were well correlated with plasma levels of meterelin.
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Affiliation(s)
- E Hudon
- Faculté de Pharmacie, Université de Montréal, Québec, Canada
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106
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Thomasin C, Merkle HP, Gander BA. Physico-chemical parameters governing protein microencapsulation into biodegradable polyesters by coacervation. Int J Pharm 1997. [DOI: 10.1016/s0378-5173(96)04810-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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107
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Microencapsulation of rh-erythropoietin, using biodegradable poly(d,l-lactide-co-glycolide): protein stability and the effects of stabilizing excipients. Eur J Pharm Biopharm 1997. [DOI: 10.1016/s0939-6411(96)00017-3] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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108
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Mi FL, Tseng YC, Chen CT, Shyu SS. Preparation and release properties of biodegradable chitin microcapsules: I. Preparation of 6-mercaptopurine microcapsules by phase separation methods. J Microencapsul 1997; 14:15-25. [PMID: 8994072 DOI: 10.3109/02652049709056464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Chitin [poly-(N-acetyl-1,4-beta-D-glucopyranosamine)] microcapsules were prepared by the simple desolvation and the non-solvent addition phase separation methods. In the simple desolvation method, chitin droplets were dropped into the desolvation agent (water, ethanol, or acetone) and microcapsules soon formed. Several solvent-nonsolvent pairs: N,N-dimethylacetamide (DMAc)-water, DMAc-ethanol, DMAc-propanol, DMAc-n-butanol, and DMAc-acetone with different solubility parameter difference, (delta delta) were chosen to prepare chitin microcapsules containing 6-mercaptopurine by using the non-solvent-addition phase separation method. The results showed that the surface morphology and release behaviour of the microcapsules were greatly affected by different solvent-nonsolvent pairs. The surface of microcapsules prepared from the system of high delta delta was more smooth than those from the systems of low delta delta. The drug content using the simple desolvation method increased with decreasing delta delta because of the higher film formation rate of the microcapsules. On the other hand, the drug content using the nonsolvent addition method was lower than that using the simple desolvation method because of the dispersion forces, applied by mechanical stirring. Microcapsules prepared by the simple desolvation method had a narrower size distribution and larger mean size than those prepared by the nonsolvent addition method.
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Affiliation(s)
- F L Mi
- Department of Chemical Engineering, National Central University, Chung-Li, Taiwan, ROC
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109
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Sustained release of a water-soluble GP IIb/IIIa antagonist from copoly(dl-lactic/glycolic)acid microspheres. Int J Pharm 1997. [DOI: 10.1016/s0378-5173(96)04780-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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110
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Roskos KV, Maskiewicz R. Degradable controlled release systems useful for protein delivery. PHARMACEUTICAL BIOTECHNOLOGY 1997; 10:45-92. [PMID: 9160368 DOI: 10.1007/0-306-46803-4_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- K V Roskos
- Matrix Pharmaceutical, Inc., Fremont, California 94555, USA
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111
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Li Y, Nothnagel J, Kissel T. Biodegradable brush-like graft polymers from poly(d,l-lactide) or poly(d,l-lactide-co-glycolide) and charge-modified, hydrophilic dextrans as backbone—Synthesis, characterization and in vitro degradation properties. POLYMER 1997. [DOI: 10.1016/s0032-3861(97)00178-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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112
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Ogawa Y. Injectable microcapsules prepared with biodegradable poly(alpha-hydroxy) acids for prolonged release of drugs. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 1997; 8:391-409. [PMID: 9105978 DOI: 10.1163/156856297x00173] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this paper, microencapsulation techniques for the preparation of drug-containing monolithic microcapsules for prolonged release using biodegradable poly(alpha-hydroxy) acids, such as polylactic acid, poly(lactide-co-glycolide) and copoly(lactic/glycolic) acid are reviewed. Phase separation, solvent evaporation, and spray drying procedures are discussed. In order to achieve controlled-release formulations of highly water-soluble drugs that are entrapped efficiently, various manufacturing techniques and procedures have been developed. Degradation of poly(alpha-hydroxy) acids is altered by the copolymer ratio and molecular weight of the polymer used to make microcapsules and the amounts of released microencapsulated drugs correlate almost linearly with polymer degradation, indicating that controlled-release formulations, which release drugs over different times, can be prepared using suitable poly(alpha-hydroxy) acids with different degradation rates.
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Affiliation(s)
- Y Ogawa
- DDS Research Laboratories, Takeda Chemical Industries, Ltd., Osaka, Japan
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113
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Fitzgerald J, Corrigan O. Investigation of the mechanisms governing the release of levamisole from poly-lactide-co-glycolide delivery systems. J Control Release 1996. [DOI: 10.1016/0168-3659(96)01450-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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114
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Effects of GLIADEL® wafer initial molecular weight on the erosion of wafer and release of BCNU. J Control Release 1996. [DOI: 10.1016/0168-3659(96)01371-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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115
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Thomasin C, Corradin G, Men Y, Merkle HP, Gander B. Tetanus toxoid and synthetic malaria antigen containing poly(lactide)/poly(lactide-co-glycolide) microspheres: importance of polymer degradation and antigen release for immune response. J Control Release 1996. [DOI: 10.1016/0168-3659(96)01363-6] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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116
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Parenteral protein delivery systems using biodegradable polyesters of ABA block structure, containing hydrophobic poly(lactide-co-glycolide) A blocks and hydrophilic poly(ethylene oxide) B blocks. J Control Release 1996. [DOI: 10.1016/0168-3659(95)00163-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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117
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In vitro degradation of nanospheres from poly(D,L-lactides) of different molecular weights and polydispersities. Int J Pharm 1996. [DOI: 10.1016/0378-5173(95)04258-x] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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118
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Preparation of hydrophilic monodisperse microspheres by radiation precipitation polymerization and its characteristics. Eur Polym J 1995. [DOI: 10.1016/0014-3057(95)00068-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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119
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Controlled intraocular delivery of ganciclovir with use of biodegradable scleral implant in rabbits. J Control Release 1995. [DOI: 10.1016/0168-3659(95)00074-i] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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120
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Abstract
The in vitro degradation behaviour of a wide range of poly(D,L-lactic-co-glycolic acid) (PLGA) has been examined in terms of degree of degradation and morphological change during an incubation period of up to 53 d. Gel permeation chromatography and differential scanning calorimetry were employed to characterize their degradation profiles. It was found that amorphous PLGA exhibited a transient multiple crystallization behaviour of D- or L-lactic acid oligomers during degradation. This indicated that the hydrolytic scission of ester bonds tends to primarily target the linkage between glycolic acid and D- or L-lactic acid or glycolic acid. In addition, two distinctive glass transition temperatures appeared when these crystallization phenomena occurred, suggesting the transient presence of fast and slowly eroding polymer domains within microspheres during the degradation. This study supports the heterogeneous bulk degradation for PLGA microspheres which has been proposed recently for a large specimen.
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Affiliation(s)
- T G Park
- School of Pharmacy, Temple University, Philadelphia, PA 19140, USA
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121
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122
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Fujioka K, Takada Y, Sato S, Miyata T. Novel delivery system for proteins using collagen as a carrier material: the minipellet. J Control Release 1995. [DOI: 10.1016/0168-3659(94)00107-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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123
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124
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Gander B, Wehrli E, Alder R, Merkle HP. Quality improvement of spray-dried, protein-loaded D,L-PLA microspheres by appropriate polymer solvent selection. J Microencapsul 1995; 12:83-97. [PMID: 7730960 DOI: 10.3109/02652049509051129] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim was to study the effect of the type of polymer solvent on characteristics of microspheres produced by spray drying. The water-soluble model protein, bovine serum albumin (BSA) was microencapsulated into biodegradable poly(D,L-lactic acid) using the following 10 different polymer solvents: acetaldehyde dimethyl acetal, acetone, dichloromethane, dioxane, ethyl acetate, ethyl vinyl ether, nitromethane, tetrahydrofuran, 1,1,1-trichloroethane, and 1,1,2-trichloroethylene. These solvents having similar toxicity levels differ greatly in their physico-chemical characteristics such as boiling point, vapour pressure, miscibility and interfacial tension with an aqueous phase, and solubility parameter. The effect of these solvents on microsphere morphology was studied by SEM-micrographs. Regular particle morphology was obtained when dichloromethane, ethyl acetate, or nitromethane was used as the polymer solvent, whereas the trichlorinated solvents, tetrahydrofuran, and dioxane produced a substantial number of coalesced particles. The results are interpreted in terms of boiling point, vapour pressure, and polymer-solvent affinity. Further, BSA-loading and -integrity in the microspheres, and burst release were analysed. The theoretical loading of 2.9% was attained with dichloromethane, ethyl acetate and nitromethane, in agreement with observations of particle morphology. HPLC- and SDS-PAGE analysis of the microencapsulated BSA did not show any protein degradation or dimerization, whereas solid-phase ELISA clearly revealed that the in vitro protein antigenicity was substantially reduced (50%), particularly by water miscible solvents. Dichloromethane and ethyl acetate did not show any detrimental effect on protein antigenicity. Finally, burst release could be related again to particle morphology, with dichloromethane and nitromethane giving a burst release of only 5%. In conclusion, dichloromethane, ethyl acetate and nitromethane proved to be the most suitable solvents for the polymer-protein system studied.
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Affiliation(s)
- B Gander
- Department of Pharmacy, Swiss Federal Institute of Technology, Zürich
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125
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Shigeyuki T, Yoshiaki U, Hajime T, Yasuaki O. Preparation and characterization of copoly(dl-lactic/glycolic acid) microparticles for sustained release of thyrotropin releasing hormone by double nozzle spray drying method. J Control Release 1994. [DOI: 10.1016/0168-3659(94)90227-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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126
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Volland C, Wolff M, Kissel T. The influence of terminal gamma-sterilization on captopril containing poly(d,l-lactide-co-glycolide) microspheres. J Control Release 1994. [DOI: 10.1016/0168-3659(94)90012-4] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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127
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Okada H, Doken Y, Ogawa Y, Toguchi H. Sustained suppression of the pituitary-gonadal axis by leuprorelin three-month depot microspheres in rats and dogs. Pharm Res 1994; 11:1199-203. [PMID: 7971724 DOI: 10.1023/a:1018905403359] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The pharmacological effects of leuprorelin three-month depot microspheres were investigated in rats and dogs. After s.c. and i.m. injection, the microspheres provided similar linear drug release and sustained serum drug levels for 3 months. Persistent suppression of serum LH, FSH (in rats) and testosterone (in rats and dogs) for over 16 weeks was achieved when the microspheres were given at a dose of 100 (rat) and 25.6 (dog) micrograms/kg/day. These hormone release responses upon periodic challenge tests revealed that a single injection of the microspheres caused dramatic suppression of the function of the pituitary-gonadal system for 15 weeks in rats. The growth of the genital organs was also suppressed dose-dependently by injection of the microspheres over 3 months; the strongest suppression was achieved at a dose of 100 micrograms/kg/day. This three-month depot formulation is expected to be more convenient than the one-month depot with improved patient compliance and therapeutic effects.
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Affiliation(s)
- H Okada
- DDS Research Laboratories, Takeda Chemical Industries, Ltd., Osaka, Japan
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128
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Niwa T, Takeuchi H, Hino T, Kunou N, Kawashima Y. In vitro drug release behavior of D,L-lactide/glycolide copolymer (PLGA) nanospheres with nafarelin acetate prepared by a novel spontaneous emulsification solvent diffusion method. J Pharm Sci 1994; 83:727-32. [PMID: 8071830 DOI: 10.1002/jps.2600830527] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Nanospheres with D,L-lactide/glycolide copolymer (PLGA) were prepared as a biodegradable and biocompatible polymeric carrier for peptide drugs by a novel spontaneous emulsification solvent diffusion method. Nafarelin acetate (NA), a luteinizing hormone-releasing hormone analogue, was employed as a model peptide drug to investigate the encapsulation efficiency. The drug and PLGA, dissolved in an acetone-dichloromethane-water mixture, were poured into an aqueous solution of polyvinyl alcohol under moderate stirring at room temperature. Spontaneous emulsification arising from a rapid diffusion of acetone from the organic to the aqueous phase enables preparation of PLGA submicron spheres 200-300 nm in size. The entrapment of NA in nanospheres was improved by blending low molecular weight (Mw = 4500) PLGA with higher molecular weight PLGA due to the synergistic effect of the rapid deposition of PLGA and the ionic interaction between NA and PLGA. By coadmixing a small amount of negatively charged phospholipids such as dipalmitoyl phosphatidylglycerol or dicetyl phosphate, the leakage of water-soluble NA was further prevented. The NA encapsulated in PLGA nanospheres was more stable than native NA in acidic medium (pH = 1.2). The drug-release behavior from nanospheres suspended in the disintegration test solution no. 1 (Japanese Pharmacopeia XII) exhibited a biphasic pattern. It was found tht the initial burst of release might be due to the degradation of the PLGA chain, as monitored by gel permeation chromatography. At a later stage, the drug was released more slowly, the rate of which was determined by the diffusion of the drug in the porous matrix structure.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T Niwa
- Department of Pharmaceutical Engineering, Gifu Pharmaceutical University, Japan
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129
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Formulation and in vitro release study on poly (dl-lactide) microspheres containing hydrophilic compounds: glycine homopeptides. J Control Release 1994. [DOI: 10.1016/0168-3659(94)90261-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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130
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O'Hagan D, Jeffery H, Davis S. The preparation and characterization ofpoly(lactide-co-glycolide) microparticles: III. Microparticle/polymer degradation rates and the in vitro release of a model protein. Int J Pharm 1994. [DOI: 10.1016/0378-5173(94)90201-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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131
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Hiroaki O, Masaki Y, Toshiro H, Yayoi I, Shigeru K, Yasuaki O, Hajime T. Drug delivery using biodegradable microspheres. J Control Release 1994. [DOI: 10.1016/0168-3659(94)90159-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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132
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133
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Abstract
Poly(D,L-lactide) (DL-PLA) and poly(D,L-lactide-co-glycolide) (DL-PLGA) microspheres containing a non-steroidal anti-inflammatory model drug, piroxicam, were prepared by a spray drying process. The microspheres were characterized for surface morphology by scanning electron microscopy, particle size distribution by laser diffraction spectrometry, drug content and in vitro drug release. The diameters of the microspheres ranged from 1 to 15 microns. The DL-PLA particles appeared to be more spherical and smooth than the DL-PLGA particles, which showed a more undulated surface. Piroxicam content in the microspheres was 10%. A very high encapsulation efficiency of 99.0% was achieved with both polymers. In vitro release studies were carried out in a flow-through cell. The in vitro release rate of the drug from the DL-PLA microspheres was very slow. Less than 20% of the loaded drug was released within 10 d. The release mechanism was diffusion controlled and followed a square root of time relationship. Only a very small initial burst effect was observed. In contrast, the DL-PLGA microspheres provided a much faster drug release: about 50% was released within the first 5 h of the experiment. The mechanism for piroxicam release from the DL-PLA microspheres is not matrix erosion, but mainly drug diffusion through the intact polymer barrier. For the DL-PLGA microspheres, a pore diffusion release mechanism is proposed.
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Affiliation(s)
- B W Wagenaar
- Christian-Albrecht-University, Department of Pharmaceutical Technology, Kiel, Germany
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134
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Sánchez A, Vila-Jato J, Alonso MJ. Development of biodegradable microspheres and nanospheres for the controlled release of cyclosporin A. Int J Pharm 1993. [DOI: 10.1016/0378-5173(93)90369-q] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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135
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Kawashima Y, Iwamoto T, Niwa T, Takeuchi H, Hino T. Role of the solvent-diffusion-rate modifier in a new emulsion solvent diffusion method for preparation of ketoprofen microspheres. J Microencapsul 1993; 10:329-40. [PMID: 8377091 DOI: 10.3109/02652049309031523] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A new emulsion solvent diffusion method to prepare the microspheres of ketoprofen with an acrylic polymer was developed by utilizing sugar esters as solvent diffusion modifiers. The microspheres were produced via transient o/w emulsion droplets of the polymer, which was formed by the interaction of drug and water-miscible organic solvent, e.g. ethanol. The solvent consisting in oil droplets diffused into the outer aqueous medium. In the droplets, ethanol interacted with ketoprofen via hydrogen bonding between -OH group of ethanol and both -COOH and = CO groups of ketoprofen. These hydrogen bonds made ethanol solution strongly hydrophobic. The sugar ester added in the ethanol could inhibit such intermolecular interaction between ethanol and the = CO group of ketoprofen. Modulation in the binding force of ketoprofen-ethanol by the sugar ester contributed to achieving a desirable initial ethanol diffusion rate from the oil droplets for the formation of ketoprofen microspheres with high yield (> 85 per cent) and drug entrapment ratio (> 90 per cent).
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Affiliation(s)
- Y Kawashima
- Gifu Pharmaceutical University, Pharmaceutical Engineering Department, Japan
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136
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Couvreur P, Puisieux F. Nano- and microparticles for the delivery of polypeptides and proteins. Adv Drug Deliv Rev 1993. [DOI: 10.1016/0169-409x(93)90046-7] [Citation(s) in RCA: 174] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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137
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138
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Scholes P, Coombes A, Illum L, Daviz S, Vert M, Davies M. The preparation of sub-200 nm poly(lactide-co-glycolide) microspheres for site-specific drug delivery. J Control Release 1993. [DOI: 10.1016/0168-3659(93)90103-c] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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139
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140
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Kadowaki S, Sugimoto K, Tsurumaki Y, Tabata Y, Ikada Y, Fujita J, Mori KJ. Application of poly(L-lactic acid) particles for the suppression of genetic resistance to bone marrow allografts by reticuloendothelial system-blockade. Biomed Pharmacother 1993; 47:385-91. [PMID: 8068860 DOI: 10.1016/0753-3322(93)90103-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have recently successfully achieved bone marrow allografts by reticuloendothelial system (RES)-blockade. Long-term survival of the recipient mice after BMT was achieved without apparent evidence of graft-versus-host disease (GVHD), although T-cells were not depleted from donor marrow cells. Hemopoietic system of these recipient mice was replaced by that of donor origin [7]. As a first step to the application of this technique for human patients, we tested poly(L-lactic acid) (PLLA) particles as biodegradable particles. PLLA particles were phagocytized by macrophages when injected intravenously, and degraded slowly. PLLA has already been in clinical use as a bioresorbable suture material and matrix for drug release. We found that administration of PLLA prior to bone marrow transplantation resulted in a successful take of the allografts. In addition, PLLA was found not to show any antigenicity in normal mice.
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Affiliation(s)
- S Kadowaki
- Department of Biology, Faculty of Science, Niigata University, Japan
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141
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Affiliation(s)
- A L Adjei
- Pharmaceutical Products Division, Abbott Laboratories, North Chicago, Illinois 60064
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142
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Ramtoola Z, Corrigan OI, Barrett CJ. Release kinetics of fluphenazine from biodegradable microspheres. J Microencapsul 1992; 9:415-23. [PMID: 1403489 DOI: 10.3109/02652049209040480] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Fluphenazine-loaded microspheres were prepared using biodegradable lactide and lactide-co-glycolide polymers. Sustained release of fluphenazine was achieved with fluphenazine loadings of up to 30 per cent in both the lactide and lactide-co-glycolide polymers. Fluphenazine release from microspheres was found to increase with increasing drug loading and was most rapid from the poly-L-lactide-co-glycolide microspheres. The release profiles showed a 'lag' period followed by an accelerating release phase and in some cases a decay period, i.e. the release profiles were sigmoidal and fitted the Prout-Tomkins equation (Prout and Tompkins 1944). Consequently it was considered that polymer degradation, the primary rate-determining step controlling drug release, occurred by a mechanism involving propagation of active sites, drug release reflecting the spread of this degradation throughout the polymer.
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Affiliation(s)
- Z Ramtoola
- Department of Pharmaceutics, School of Pharmacy, Trinity College, Dublin, Ireland
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143
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Bodmer D, Kissel T, Traechslin E. Factors influencing the release of peptides and proteins from biodegradable parenteral depot systems. J Control Release 1992. [DOI: 10.1016/0168-3659(92)90014-i] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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144
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145
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Yamaguchi K, Anderson JM. Biocompatibility studies of naltrexone sustained release formulations. J Control Release 1992. [DOI: 10.1016/0168-3659(92)90085-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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146
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Camarata PJ, Suryanarayanan R, Turner DA, Parker RG, Ebner TJ. Sustained release of nerve growth factor from biodegradable polymer microspheres. Neurosurgery 1992; 30:313-9. [PMID: 1620291 DOI: 10.1227/00006123-199203000-00001] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Although grafted adrenal medullary tissue to the striatum has been used both experimentally and clinically in parkinsonism, there is a definite need to augment long-term survival. Infusion of nerve growth factor (NGF) or implantation of NGF-rich tissue into the area of the graft prolongs survival and induces differentiation into neural-like cells. To provide for prolonged, site-specific delivery of this growth factor to the grafted tissue in a convenient manner, we fabricated biodegradable polymer microspheres of poly(L-lactide)co-glycolide (70:30) containing NGF. Biologically active NGF was released from the microspheres, as assayed by neurite outgrowth in a dorsal root ganglion tissue culture system. Anti-NGF could block this outgrowth. An enzyme-linked immunosorbent assay detected NGF still being released in vitro for longer than 5 weeks. In vivo immunohistochemical studies showed release over a 4.5-week period. This technique should prove useful for incorporating NGF and other growth factors into polymers and delivering proteins and other macromolecules intracerebrally over a prolonged time period. These growth factor-containing polymer microspheres can be used in work aimed at prolonging graft survival, treating experimental Alzheimer's disease, and augmenting peripheral nerve regeneration.
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Affiliation(s)
- P J Camarata
- Department of Neurosurgery, University of Minnesota, Minneapolis
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147
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Abstract
The immunogenic potential of tetanus toxoid (TT) was compared when either adsorbed to aluminium hydroxide (TT-alum) or entrapped in microparticles consisting of poly(D,L-lactic-co-glycolic acid) (PLA:PGA, 55:45) derived polymers. Furthermore, the effect of administering the microparticles in an aqueous buffer or water-in-oil emulsion on the TT immunogenicity was also investigated. When mice were immunized with the different formulations, similar levels of anti-TT antibodies were observed during the primary IgG response. The choice of the carrier seemed to play an important role for both the level and maintenance of the secondary IgG response, attained as a consequence of a booster immunization with TT-alum. The strongest secondary antibody response was obtained by priming with TT-containing microparticles, resuspended in water-in-oil emulsions. As expected, incomplete Freund's adjuvant (IFA) proved to be a more potent adjuvant than peanut oil, whereas resuspension of the microparticles in aqueous solution induced a relatively less efficient antibody response. Overall, microencapsulated TT primed the mice more effectively, since the secondary antibody response was higher and persisted longer compared with TT-alum priming. These results indicate that in addition to TT maintaining its antigenicity after microencapsulation, the microparticles also potentiate its immunogenic properties. This approach should prove very useful for designing more effective vaccines.
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Affiliation(s)
- I Esparza
- Department of Drug Delivery Systems, Sandoz Pharma, Basel, Switzerland
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148
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Heinrich N, Fechner K, Berger H, Lorenz D, Albrecht E, Rafler G, Schäfer H, Mehlis B. In-vivo release of a GnRH agonist from a slow-release poly(lactide-glycolide) copolymer preparation: comparison in rat, rabbit and guinea-pig. J Pharm Pharmacol 1991; 43:762-5. [PMID: 1686903 DOI: 10.1111/j.2042-7158.1991.tb03478.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Different batches of 50:50 poly((+-)-lactide-glycolide) copolymer (PLG) were used as biodegradable carriers for D-Phe6-gonadotropin-releasing hormone (GnRHa) in the form of injectable long-acting implants loaded with 10% GnRHa and tracer amounts of [125I]GnRHa. After their injection subcutaneously into rats, rabbits, and guinea-pigs, the release kinetics of the peptide were determined by counting the radioactivity remaining in the implants (i) after recovery from the rats after death or (ii) directly on the skin above the injection site of rabbits and guinea-pigs in-vivo. No significant differences in the release pattern of the peptide amongst the three species whether the release process was controlled by diffusion or by degradation of the polymeric matrix were found. It is concluded that the results of in-vivo release tests using laboratory animals are valid for man and that enzymes are not involved in the degradation of the polymeric matrix. The results may be of general importance for the use of long-term release PLG formulations of highly active drugs, especially peptides and proteins.
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Affiliation(s)
- N Heinrich
- Institute of Drug Research, Berlin, Germany
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149
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Wada R, Hyon SH, Nakamura T, Ikada Y. In vitro evaluation of sustained drug release from biodegradable elastomer. Pharm Res 1991; 8:1292-6. [PMID: 1796048 DOI: 10.1023/a:1015860030772] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Poly(DL-lactic acid) (PLA), poly(epsilon-caprolactone) (PCL), and their copolymers (PLA-CL) with various monomer compositions were synthesized, and their properties as matrix for the sustained release of drugs were evaluated. The copolymerization technique produced very soft films which incorporated the drugs without deterioration of the elastic properties. Cisplatin and MD-805 were loaded in the films by casting the polymer solution containing the drugs. Fractions of the drugs released from the PLA-CL films were governed by the initial loading, the film thickness, and the polymer molecular weight. The drug release profiles obeyed the classical Fickian diffusion equation at least in the early stage, but significant hydrolytic degradation of the matrix polymers occurred in the later stage, influencing the kinetics of drug release. The monomer composition of copolymer affected the release profile more strongly than the initial molecular weight of the copolymer.
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Affiliation(s)
- R Wada
- Research Center for Biomedical Engineering, Kyoto University, Japan
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150
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Wang H, Schmitt E, Flanagan D, Linhardt R. Influence of formulation methods on the in vitro controlled release of protein from poly (ester) microspheres. J Control Release 1991. [DOI: 10.1016/0168-3659(91)90127-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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