呱西替柳滴丸的制备及其溶出度研究

采用差示扫描量热法、扫描电子显微镜术和溶出试验研究了呱西替柳-聚乙二醇(GA-PEG)低共熔混合物及其滴丸。结果表明,随着 PEG 分子量增高,低共熔混合物中药物的比例增加,但低共熔温度与PEG 分子量之间并无规律性。其中 GA-PEG4000的滴丸有较大的溶出度,加入崩解剂有助于增加滴丸与溶出介质接触的表面积,进而提高溶出度。     

Implication of inclusion complexation of glimepiride in cyclodextrin-polymer systems on its dissolution, stability and therapeutic efficacy

The effect of complexation of glimepiride, a poorly water-soluble antidiabetic drug, with β-cyclodextrin and its derivatives (HP-β-CyD and SBE-β-CyD) in presence of different concentrations of water-soluble polymers (HPMC, PVP, PEG 4000 and PEG 6000) on the dissolution rate of the drug has been investigated. The results revealed that the dissolution rate of the drug from these ternary systems is highly dependent on polymer type and concentration. The dissolution rate of the drug from ternary systems containing PEG 4000 or PEG 6000 seems to be generally higher than from systems containing HPMC or PVP. An optimum increase in the dissolution rate of the drug was observed at a polymer concentration of 5% for PEG 4000 or PEG 6000 and at 20% concentration of HPMC or PVP. The dissolution rate of the drug from the ternary system glimepiride–HP-β-CyD–5% PEG 4000 was high compared to the other systems. Tablets containing the drug or its equivalent amount of this ternary system were prepared and subjected to accelerated stability testing at 40 °C/75% R.H. to investigate the effect of storage on the chemical stability as well as therapeutic efficacy of the tablets. The results revealed stability of the tablets and consistent therapeutic efficacy on storage.     

In Vitro and In Vivo Study of Poly(ethylene glycol) Conjugated Ibuprofen to Extend the Duration of Action

Ibuprofen-polyethylene glycol (PEG) conjugates (PEG-Ibu) were prepared and their potential as a prolonged release system was investigated. Two PEG-Ibu conjugates were synthesized from Ibuprofen and PEG with two different molecular weights by esterification in the presence of DCC and DMAP. The PEG-Ibu conjugates were characterized by FT-IR, (1)H NMR, Mass spectroscopy and DSC analysis. The solubility study in aqueous system showed an increase in solubility of conjugates. The dissolution / hydrolysis studies showed a specific acid-base catalysis pattern dependent on the pH of the medium. This indicated a good chemical stability in aqueous buffer solution of acidic medium and the extended release behavior was found in both prodrugs after 9 hour. The results demonstrate that, in the same condition, the rate of hydrolysis for PEG(4000)-Ibu is slower than other. The Writhing induced by acetic acid experiment and paw edema test after oral administration showed that both conjugates had extended analgesic and anti-inflammatory effects compared with Ibuprofen. These results suggest that PEG-Ibu could be a promising NSAID prodrug with an extended pharmacological effect owing to delayed-release of parent drug.     

Improvement of the dissolution kinetics of SR 33557 by means of solid dispersions containing PEG 6000

Solid dispersions of SR 33557 in preparations containing from 30 to 80% w/w polyethylene glycol 6000 (PEG 6000) were prepared by the fusion method. The solubility of the drug substance either alone or in solid dispersions was determined in pH 1.2 and 4.5 media (extraction fluid NFXII, without enzyme). A large increase in the solubility was noted from the 80% w/w PEG preparation. A wettability study performed by measuring the contact angle on tablets of either drug substance or PEG 6000, or solid dispersions, revealed a minimal contact angle for the 80% w/w PEG 6000 solid dispersion (eutectic composition of SR 33557/PEG 6000 phase diagram). Dissolution kinetic analysis performed at pH 1.2 on all solid dispersions, on the physical mixtures containing 70 and 80% w/w PEG 6000, and on SR 33557 alone, showed a maximum release rate (100%) for the solid dispersions containing 70 and 80% w/w PEG 6000. The dissolution rate of the physical mixtures was faster than that of the drug substance alone but remained, however, lower than that of the solid dispersions, at the same composition. It was also observed that the dissolution rate, at pH 1.2 and 4.5, of the 70% w/w PEG 6000 solid dispersion was practically pH independent, which was not the case for the drug substance alone. The latter solid dispersion showed a slowing down of the dissolution kinetics after 3 months storage at 50°C whereas no change in the dissolution rate was observed following storage for 12 months at 25°C.     

Synthesis, characterization and stability of dendrimer prodrugs

The design, synthesis and characterization of a series of zero generation (G0) PAMAM dendrimer-based prodrugs for the potential enhancement of drug solubility and bioavailability are described. Naproxen, a poorly water-soluble drug, was conjugated to dendrimers either directly by an amide bond or by ester bonds using either L-lactic acid or diethylene glycol as a linker. All of the prodrugs were more hydrophilic than the parent drug, as evaluated by drug partitioning between 1-octanol and phosphate buffer (pH 7.4). Hydrolysis of the conjugates was measured at 37 degrees C in hydrochloric acid buffer (pH 1.2), phosphate buffer (pH 7.4), borate buffer (pH 8.5) and in 80% human plasma. The amide conjugate and both ester conjugates were chemically stable at all pHs over 48 h of incubation. Naproxen was enzymatically released from both ester conjugates in plasma; the lactic ester conjugate hydrolyzed slowly with only 25% of naproxen released after 24h, the diethylene glycol ester conjugate cleaved rapidly following pseudo first order kinetics (t(1/2) = 51 min). G0 PAMAM dendrimer prodrugs with an appropriate linker (diethylene glycol) show good potential as carriers for oral delivery.     

Physical Stability of Solid Dispersions Containing Triamterene or Temazepam in Polyethylene Glycols

The effect of storage on the physical stability of solid dispersions of triamterene or temazepam in polyethylene glycols was studied using differential scanning calorimetry (DSC), particle-size analysis and dissolution methods. The enthalpies of fusion of the carriers, without included drug and previously fused and crystallized, increased on storage. Analysis of similarly treated solid dispersions, containing either 10% temazepam or 10% triamterene, showed that each drug influenced the morphology of the polyethylene glycol (PEG). The enthalpies and melting points of the solidus components of the dispersions' carriers were initially reduced after preparation, but on storage these increased. The particle sizes of the drugs dispersed in the PEGs increased on storage. The changes in dissolution after storage of triamterene or temazepam dispersions were smaller for dispersions in PEG 1500 than for dispersions in PEGs of higher molecular weight (PEG 2000, PEG 4000 or PEG 6000) in which the reduction in dissolution was particularly marked during the first month of storage. The rank order of changes in dissolution were PEG 1500 ? PEG 2000 < PEG 4000 ～ PEG 6000.     

Physicochemical characterization and in vivo properties of Zolpidem in solid dispersions with polyethylene glycol 4000 and 6000.

Solid dispersions and physical mixtures of Zolpidem in polyethylene glycol 4000 (PEG 4000) and 6000 (PEG 6000) were prepared with the aim to increase its aqueous solubility. These PEG based formulations of the drug were characterized in solid state by FT-IR spectroscopy, X-ray powder diffraction, and differential scanning calorimetry. By these physical determinations no drug-polymer interactions were evidenced. Both solubility and dissolution rate of the drug in these formulations were increased. Each individual dissolution profile of PEG based formulation fitted Baker-Lonsdale and first order kinetic models. Finally, significant differences in ataxic induction time were observed between Zolpidem orally administered as suspension of drug alone and as solid dispersion or physical mixture. These formulations, indeed, showed almost two- to three-fold longer ataxic induction times suggesting that, in the presence of PEG, the intestinal membrane permeability is probably the rate-limiting factor of the absorption process. Copyright     

The mechanochemical preparation of solid disperse systems of ibuprofen-polyethylene glycol

The method of mechanical activation is applied to obtain a solid-state dispersion of ibuprofen in polyethylene glycol (PEG). The release rate and solubility of the drug was found to depend on carrier molecular weight and its weight fraction. The highest release rate and solubility were achieved in systems containing equimolar amounts of the drug and PEG 4000 or PEG 6000. It was shown by IR-spectroscopy and fluorescence measurements that the mechanical treatment gives rise to an interaction between ibuprofen and PEG that was a cause of the effects observed.     

Release and rectal absorption of ethosuximide from suppositories in rabbits

Ethosuximide was formulated in different suppository bases. In vitro release experiment demonstrated more rapid and higher release of the drug from water soluble polyethylene glycol (PEG) bases than from Witepsol fatty bases. Rectal administration in PEG 400:4000 and 400:6000 to rabbits gave high plasma levels where Cmax was 45.66 and 42.66 micrograms.ml-1, respectively; while, in the presence of Witepsol E76 and W35 it was 34.00 and 28.33 micrograms.ml-1, respectively. The systemic availability was 89.39%, 82.72%, 58.80% and 47.45% when the bases were PEG 400:4000, PEG 400:6000, Witepsol E76 and Witepsol W35, respectively.     

The effect of the molecular weight of polyethylene glycol on the bioavailability of paracetamol-polyethylene glycol solid dispersions

A controlled study of the bioavailability of paracetamol in solid dispersion with PEG 6000, 10000 and 20000 has been made. The total amount of paracetamol excreted in urine increased with molecular weight of the PEG, but the rate of absorption of the drug was unaffected.     

通心舒滴丸成型工艺研究

目的　通过试验选择通心舒滴丸最佳的成型工艺。方法　以滴丸的溶散时间、丸重差异变异系数及外观质量作为综合评定指标,对药物清膏与基质的比例、基质配比(PEG4 0 0 0与PEG6 0 0 0的比例)、滴速、药液温度以正交试验法实验,优选出滴丸最佳成型工艺。结果　以清膏∶基质 =1∶2 5,PEG4 0 0 0∶PFG6 0 0 0 =1∶1,滴速为 4 5滴·min-1,药液温度为 85℃进行滴制,为最佳成型工艺。结论　本试验筛选出滴丸的最佳成型工艺,滴丸外观性状好、溶散度较好,丸重差异小,符合滴丸剂的质量标准。     

Synthesis, stability studies, anti-inflammatory activity and ulcerogenicity of morpholinoalkyl ester prodrugs of niflumic acid

In search for potential prodrugs for anti-inflammatory drug candidates in the niflumate series, novel morpholinoalkyl ester prodrugs of niflumic acid (CAS 4394-00-7) 5a-b were prepared by esterification of appropriate morpholinylalkyl alcohols 3a-b with niflumic acid 4 in the presence of dicyclohexyl carbodiimide (DCC) and catalyst dimethylamino pyridine (DMAP) at 0-5 degrees C. The structures were confirmed by elemental and spectral data (UV, IR, 1H-NMR, 13C-NMR, and EI-MS). The ester prodrugs 5a-b showed better solubility than the parent drug niflumic acid 4 in simulated gastric fluid (SGF) and phosphate buffer (pH 7.4). The in vitro hydrolysis studies were conducted at pH 1.3 (SGF), phosphate buffer (pH 7.4) and in human plasma diluted with phosphate buffer (pH 7.4) at 37+/-0.5 degrees C using HPLC with UV detection. The ester prodrugs 5a-b were quantitatively hydrolyzed to the parent drug niflumic acid 4 by enzymatic and/or chemical means. It is observed that an increase in the carbon chain length rendered the prodrugs 5a-b more stable in phosphate buffer (pH 7.4) than in pH 1.3 (SGF), but they were rapidly hydrolyzed in human plasma at 37+/-0.5 degrees C. They exhibited longer hydrolytic half-lives of 16.11-53.30 h in aqueous buffer solutions (pH 1.3 and 7.4) and 1.63-2.73 min in human plasma, respectively. The title compounds were evaluated in vivo for anti-inflammatory activity in carrageenan induced rat paw oedema model in rats at the doses 45, 90, 150 mg/kg b.w. The test compounds exhibited good anti-inflammatory activity (46.6-53.2 % at the dose of 150 mg/kg b. w.) with respect to niflumic acid (78.7 % at the dose of 90 mg/kg b.w.). The compounds were also screened for in vivo ulcerogenicity, it was observed that the prodrug 5b was significantly less irritating to gastric mucosa than compound 5a and the parent drug niflumic acid 4 following single and chronic oral administration in rats.     

Oligoethylene ester derivatives of ketoprofen,naproxen and diclofenac as oral prodrugs: a pharmacological evaluation

Polyoxyethylene esters of ketoprofen (1a-e), naproxen (2a-e) and diclofenac (3a-e) were tested in vitro to determine their stability in pH 7.4 phosphate buffer and in simulated gastric fluid (pH 2.0 buffer) and their susceptibility in undergoing enzymatic cleavage in human plasma. Furthermore their in vivo antiinflammatory and analgesic activity and GI toxicity were evaluated in rodents. All the prodrugs showed a good stability both in pH 7.4 phosphate buffer and in pH 2.0 buffer. They were readily hydrolyzed by human plasma and, for each group of prodrugs, no significant difference in hydrolysis rate was observed as the length of the oligoethylene chain increased. Esters 1a-e, 2a-e and 3a-e showed an anti-inflammatory activity (expressed as inhibition percent of carrageenan-induced edema in the rat) similar to that of their respective parent drug although at higher doses. The results obtained in the writhing test in mice demonstrated that all the prodrugs tested exhibited, following acute administration, a good analgesic effect. Furthermore these esters were significantly less irritating to the gastric mucosa, although administered at doses higher than the respective parent drug.     

Comparative assessment of two indices of drug induced permeability changes in the perfused rat intestine

In the present study, two indices of acute intestinal permeability changes were investigated as measurements of drug induced intestinal damage. The first method was based on 14C-polyethylene glycol (PEG) 4000 permeability assessment and the second was based on histological evaluation of the intestine. The test compounds were ibuprofen, ketoprofen and naproxen and the alanine, glycine and phenylalanine amide derivatives of ibuprofen. Perfusion studies were carried out using a rat model. Post-perfusion, the gut was fixed and tissue changes were assessed and scored. Ibuprofen, ketoprofen and naproxen altered the barrier properties of the intestine to PEG 4000 with significantly higher scores (p<0.05) for gastrointestinal toxicity relative to blank buffer. For ketoprofen, PEG 4000 permeability and intestinal damage scores increased with increasing ketoprofen concentration. Ibuprofen amide derivatives did not induce significant histological damage or PEG 4000 permeability when compared with ibuprofen. A correlation coefficient of 0.91 is obtained when intestinal damage scores are plotted against PEG 4000 permeability for all compounds. Both indices are proposed as rapid and useful measures of drug induced acute intestinal damage.     

Solidification Studies of Polyethylene Glycols,Gelucire 44/14 or their Dispersions with Triamterene or Temazepam

The solidification of polyethylene glycols (PEG 1500, PEG 2000, PEG 4000, PEG 6000), gelucire 44/14 or their dispersions containing triamterene or temazepam were studied to assess the feasibility of using these dispersions to liquid-fill hard gelatin capsules. Solidification from melts, investigated by differential scanning calorimetry using cooling cycles, showed a tendency of the drugs, carriers or their dispersions to supercool. The degree of supercooling depended on the rate of cooling, the drug content and, for the PEGs, on the molecular weight. PEG 1500 and PEG 2000 gave one morphological form, irrespective of cooling rate; PEG 4000 and PEG 6000 solidified into at least two forms, depending on the cooling rate. Incorporation of drugs affected the morphology of the PEGs during solidification. The rate of crystal growth was, furthermore, influenced by the fusion temperature, molecular weight and the degree of supercooling. The degree of crystallinity, as measured by the enthalpies of solidification, decreased with increasing cooling rate. The results show that reducing the rate of solidification could lead to incomplete solidification, giving products that are liable to change on storage.     

The properties of solid dispersions of indomethacin or phenylbutazone in polyethylene glycol

The effects of molecular weight of polyethylene glyeols (PEGs) on the dissolution rates and crystallinity of its solid dispersions with indoniethacin and phenylbutazone have been examined. The dissolution rates of both solid-dispersed drugs decreased as the molecular weight of PEG increased. The indoniethacin dissolution profiles were essentially linear using constant surface area disc methodology and a limiting dissolution rate of about 10.6 mg · min⁻¹ was observed. The phenylbutazone dissolution profiles were. however, generally linear-curvic usually giving lower release rates than the comparative indomethacin weight fractions. A limiting dissolution rate for the linear portions of the profiles was about 1.8 mg · min⁻¹. Infra-red spectra indicated that the differences between the two drugs could partly be explained on the basis of PEG crystallinity. Generally bands in the ranges 1100–1130 and 1200–1400 cm⁻¹ were poorly differentiated in indomethacin dispersions (PEG 1500, PEG 4000 and PEG 6000) but were better differentiated in phenylbutazone dispersions (PEG 4000, PEG 6000 and PEG 20,000). A greater proportion of amorphousness within the PEG moiety was predicted in indomethacin dispersions by the appearance of a new weak band at 1326 cm⁻¹ and by a decrease in intensity of the band at 845 cm⁻¹ at the expense of the peak at 960 cm⁻¹. The evidence was supported by differential scanning calorimetry. The heats of fusion were 44.7, 46.4, 47.2 and 39.5 cal · g⁻¹ for PEG 1500, PEG 4000, PEG 6000 and PEG 20.000 respectively. Heats of fusion for indomethacin dispersions (2, 5 and 10% drug) were generally lower than for the corresponding values for phenylbutazone dispersions-with the exception of PEG 20,000 dispersions. For example, values were obtained of 30.6 and 37.9 cal · g⁻¹ for PEG 1500 dispersions containing 10% indomethacin and phenylbutazone, respectively.     

Synthesis, physicochemical properties and biological evaluation of aromatic ester prodrugs of 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one (CP102): orally active iron chelators with clinical potential.

The synthesis of seven aromatic ester derivatives of 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one is described. These ester prodrugs have been designed to target iron chelators to the liver, the major iron storage organ. In principle this should improve chelation efficacy and minimize toxicity. The distribution coefficients of these ester prodrugs between 1-octanol and MOPS buffer pH 7.4 were measured together with their rates of hydrolysis at pH 2 and pH 7.4, in rat blood and liver homogenate. Esters with heteroaromatic acid moieties were found to be less stable than benzoyl analogues. The in-vivo iron mobilisation efficacy of these ester prodrugs has been compared with that of the parent drug using a 59Fe-ferritin loaded rat model. Many prodrugs were found to enhance the ability of the parent hydroxypyridinone to facilitate 59Fe excretion. However, not all prodrugs provided increased efficacy, demonstrating that lipophilicity is not the only factor which influences drug efficacy. Furthermore, no clear correlation between efficacy and susceptibility to hydrolysis was detected. The picolinic and nicotinic ester derivatives appear to offer the best potential as prodrugs as they have a relatively low LogP value and yet lead to enhanced efficacy over the parent hydroxypyridinone.     

Drug delivery systems based on trimethyl lock lactonization: poly(ethylene glycol) prodrugs of amino-containing compounds

A novel methodology for the synthesis of poly(ethylene glycol) (PEG) prodrugs of amino-containing compounds has been developed which is based on the trimethyl lock lactonization reaction. These PEG-modified double prodrugs are water soluble, and by selective modification of the specifier or trigger, plasma half-lives can be adjusted at will to result in a wide range of values. Facile syntheses of ester, carbonate, and carbamate functionalities were accomplished and combined with greater or lesser degrees of steric hindrance in the spacer group, or on the aromatic framework, to achieve predictable ranges of drug concentration in plasma. In vivo screening of PEG prodrugs was done using a M109 syngeneic solid mouse tumor model. One of the PEG-daunorubicin prodrugs, with a half-life of 2 h, was evaluated in an in vivo solid tumor panel and found to be more efficacious against ovarian tumors (SKOV3) than equivalent amounts of daunorubicin.     

Piperazinylalkyl prodrugs of naproxen improve in vitro skin permeation.

Novel morpholinyl (4a) and piperazinylalkyl (4b-e) esters were synthesized and evaluated in vitro for their properties as bioreversible topically administered dermal prodrugs of naproxen. These ionizable prodrugs exhibited various aqueous solubilities and lipophilicities, depending on the pH of medium. As indicated by octanol-buffer partition coefficients (logP(app)) at pH 7.4, all of the prodrugs were significantly more lipophilic (logP(app)=0.7-3.9) than naproxen (logP(app)=0.3). Furthermore, the most aqueous of the soluble prodrugs (4b-d) were only 2-3-fold less soluble in an aqueous buffer of pH 7.4 ( approximately 30-50 mM) than was naproxen ( approximately 100 mM). At a pH of 5.0, prodrugs showed a generally higher aqueous solubility and similar logP(app) values, compared to naproxen. The chemical and enzymatic hydrolysis of prodrugs at 37 degrees C was investigated in aqueous buffer solutions (pH 5.0 and 7.4) and in 80% human serum (pH 7.4), respectively. The prodrugs showed moderate chemical stability (t(1/2)=15-150 days at pH 5.0), and they were hydrolyzed enzymatically to naproxen, with half-lives ranging from 0.4 to 77 min. In permeation studies using post-mortem human skin in vitro, the flux of naproxen was 6.5 and 1.6 nmol/cm(2). h in a saturated aqueous buffer vehicle of pH 7.4 and 5.0, respectively. Among the prodrugs, two piperazinyl derivatives (4c and 4d) resulted in a 9- and 4-fold enhancement of permeation, respectively, when compared to naproxen itself at pH 7.4. 4c also resulted in a significantly (4-fold) better permeation than naproxen at pH 5.0. In conclusion, piperazinyl esters improved skin permeation of naproxen and are promising prodrugs of naproxen for topical drug delivery.     

Effect of drug solubility and different excipients on floating behaviour and release from glyceryl monooleate matrices

Glycerol monooleate (GMO) matrix was found to be a gastro-retentive carrier system suitable for both polar and as well as non-polar drugs. Chlorpheniramine maleate (CPM) and diazepam (DZP) were used as model drugs. Effect of PEG 4000, PEG 10000, and stearic acid on floatability and release profile was studied. Water uptake increased with increase in the loading of polar drug (CPM) and decreased with non-polar drug (DZP). Similar effect was found to occur in case of drug release. PEGs increased the release up to certain concentration and decreased thereafter. Drug release decreased linearly with concentration of stearic acid. The type and extent of mesophases formed were significantly affected by the nature of drug, excipients and their concentration. Thus the selection of suitable excipients depending on polarity of drug, could help to modulate the floatability and release profile from GMO matrices.