ABSTRACT
Hydrophilic polymer embolism (HPE) associated with endovascular therapy has steadily gained attention. We report a case of a 70-year-old man who had undergone one-debranched TEVAR. He had a history of distal arch replacement for dissecting aortic aneurysm 14 years earlier. Pseudoaneurysm at the proximal site of graft anastomosis was found on computed tomography (CT) angiogram during the follow-up. 1 debranching TEVAR was performed using the pull-through technique. Fourth days after the procedure, a skin rash appeared in the right lower extremity around the access site. Skin biopsy with pathological examination revealed HPE. We decided to observe a patient because there was no symptom of limb ischemia. Skin lesions improved and he was discharged on the 27th postoperative day. Hydrophilic polymers are widely used in the endovascular devices and there is an urgent need to better understand the complication of HPE.
ABSTRACT
abstract Amiodarone HCl is an antiarrhythmic agent, which has low aqueous solubility and presents absorption problems. This study aimed to develop inclusion complexes containing hydrophilic carriers PEG 1500, 4000 and 6000 by fusion and kneading methods in order to evaluate the increase in solubility and dissolution rate of amiodarone HCl. The solid dispersion and physical mixtures were characterized by X-ray diffraction, FT-IR spectra, water solubility and dissolution profiles. Both methods and carriers increased the solubility of drug, however PEG 6000 enhanced the drug solubility in solid dispersion better than other carriers. Different media were evaluated for the solubility study, including distilled water, acid buffer pH 1.2, acetate buffer pH 4.5 and phosphate buffer pH 6.8 at 37 ºC. Based on the evaluation of the results obtained in the study phase solubility carriers PEG 4000 and PEG 6000 were selected for the preparation of the physical mixture and solid dispersion. All formulations were prepared at drug-carrier ratios of 1:1 to 1:10(w/w). The results of in vitro release studies indicated that the solid dispersion technique by fusion method in proportion of 1:10 (w/w) increased significantly the dissolution rate of the drug. X-ray diffraction studies showed reduced drug crystallinity in the solid dispersions. FT-IR demonstrated interactions between the drug and polymers.
resumo Cloridrato de amiodarona é um agente antiarrítmico que possui baixa solubilidade aquosa e apresenta problemas de absorção. Este estudo teve como objetivo desenvolver complexos de inclusão contendo carreadores hidrofílicos PEG 1500, 4000 e 6000 através dos métodos de fusão e amassamento para avaliar o aumento da solubilidade e taxa de dissolução do cloridrato de amiodarona. As dispersões sólidas e misturas físicas foram caracterizadas por difração de raios-X, espectroscopia no infravermelho com transformada de Fourier, solubilidade em água e perfis de dissolução. Ambos os métodos e carreadores aumentaram a solubilidade do fármaco, no entanto o PEG 6000 aumentou a solubilidade do fármaco na dispersão sólida mais que os outros carreadores. Diferentes meios foram avaliados para o estudo de solubilidade, incluindo água destilada, tampão ácido pH 1,2, tampão acetato pH 4,5 e tampão fosfato pH 6,8. Com base na avaliação dos resultados obtidos no estudo de solubilidade de fases, os carreadores PEG 4000 e PEG 6000 foram selecionados para a preparação das misturas físicas e dispersões sólidas. Todas as formulações foram preparadas nas razões fármaco-carreador de 1:1 a 1:10 (p/p). Os resultados de liberação in vitro que a técnica de dispersão sólida pelo método de fusão na proporção 1:10 (p/p) aumentou significativamente a taxa de dissolução do fármaco. Estudos de difração de raios-X mostraram redução da cristalinidade do fármaco na dispersão sólida. Análise por espectroscopia no infravermelho mostrou interações entre o fármaco e o carreador.
Subject(s)
Solubility , Dissolution/analysis , Amiodarone/analysis , X-Ray Diffraction , Anti-Arrhythmia Agents/pharmacokineticsABSTRACT
OBJECTIVE: To investigate the effect of polymers, including hydrophilic polymers and swelling aids, on floatability and dissolution of ciprofloxacin hydrochloride gastro-retentive tablets. METHODS: Hydroxypropyl methyl cellulose (HPMC), hydroxyethylcellulose (HEC) and hydroxypropylcellulose (HPC) were used as hydrophilic swelling excipients, and disintegrants crospovidone (PVPP XL and PVPP XL-10) or croscarmellose sodium (CCS) were used as swelling agents to facilitate the swelling/floating and drug release. Initial floating time and floating duration were tested to evaluate buoyance, and drug dissolution was tested to evaluate the controlled release. RESULTS: Using HPMC K250 and PVPP XL as excipients for ciprofloxacin hydrochloride gastro-retentive tablets could obtain products with rapid onset of floating, long floating durion and desirable drug release. CONCLUSION: Variety and amount of polymers have dramatic effects on buoyance and drug release of gastro-retentive tablets. HPMC K250 and PVPP XL are suitable excipients for ciprofloxacin hydrochloride gastro-retentive tablets.
ABSTRACT
The purpose of the investigation highlights the formulation and optimization of floating tablets containing theophylline as a model drug. Formulations were optimized for different concentrations of cetyl alcohol, citrc acid and methocel K15M by direct compression method. The dissolution study of the tablet matrices of 9 different formulations were carried out in 0.1N HCl as the medium (pH 1.3) for 8 hours using USP type II dissolution apparatus. It was observed the floating lag time for the tablet was 30 seconds and the total floating time was more than 8 hours. The drug release pattern was simulated in different kinetic orders such as Zero Order, First Order, Higuchi, and Korsmeyer release kinetic model. From the study, we observed that Higuchi release kinetics was predominant over other release kinetics and diffusion was the drug release mechanism from the matrices. Korsmeyer-Peppas release kinetics suggests that formulation F3, F4 and F9 followed Fickian type release mechanism whereas formulation F1, F2, F5, F6, F7 and F8 followed Non-Fickian type release mechanism. Thus, it is possible to design theophylline loaded Methocel K15M sustained release matrix tablets with desirable release characteristics by judicious and critical combination of Methocel K15M with other hydrophilic materials.
ABSTRACT
The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug by a solid dispersion technique, in order to investigate the effect of these polymers on release mechanism from solid dispersions. Diazepam was used as a model drug to evaluate its release characteristics from different matrices. Solid dispersions were prepared by using polyethylene glycol 6000 (PEG-6000), HPMC, HPC and Poloxamer in different drug-to-carrier ratios (1:2, 1:4, 1:6, 1:8, 1:10). The solid dispersions were prepared by solvent method. The pure drug and solid dispersions were characterized by in vitro dissolution study. Distilled water was used as dissolution media, 1000 ml of distilled water was used as dissolution medium in each dissolution basket at a temperature of 37°C and a paddle speed of 100 rpm. The very slow dissolution rate was observed for pure Diazepam and the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. SEM (Scan-ning Electron microscope) studies shows that the solid dispersion having a uniform dispersion. Solid dispersions prepared with PEG-6000, Poloxamer showed the highest improvement in wettability and dissolution rate of Diaze-pam. Solid dispersion containing polymer prepared with solvent method showed significant improvement in the release profile as compared to pure drug, Diazepam.
ABSTRACT
The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug by a solid dispersion technique, in order to investigate the effect of these polymers on release mechanism from solid dispersions. Diazepam was used as a model drug to evaluate its release characteristics from different matrices. Solid dispersions were prepared by using polyethylene glycol 6000 (PEG-6000), HPMC, HPC and Poloxamer in different drug-to-carrier ratios (1:2, 1:4, 1:6, 1:8, 1:10). The solid dispersions were prepared by solvent method. The pure drug and solid dispersions were characterized by in vitro dissolution study. Distilled water was used as dissolution media, 1000 ml of distilled water was used as dissolution medium in each dissolution basket at a temperature of 37°C and a paddle speed of 100 rpm. The very slow dissolution rate was observed for pure Diazepam and the dispersion of the drug in the polymers considerably enhanced the dissolution rate. This can be attributed to improved wettability and dispersibility, as well as decrease of the crystalline and increase of the amorphous fraction of the drug. SEM (Scan-ning Electron microscope) studies shows that the solid dispersion having a uniform dispersion. Solid dispersions prepared with PEG-6000, Poloxamer showed the highest improvement in wettability and dissolution rate of Diaze-pam. Solid dispersion containing polymer prepared with solvent method showed significant improvement in the release profile as compared to pure drug, Diazepam.