Análisis por FTIR y DSC de complejos polielectrolito entre Eudragit® E100 y ácido benzoico como evidencia de hidrólisis de los grupos éster del polímero / FTIR and DSC analysis of polyelectrolyte complexes between Eudragit® E100 and benzoic acid as evidence of hydrolysis of the polymer ester groups

RESUMEN La obtención de complejos polielectrolito entre el polímero catiónico Eudragit® E100 y moléculas aniónicas, con neutralización adicional de un ácido inorgánico, ha sido una práctica recurrente en el área de investigación de estos sistemas de liberación controlada. En el presente trabajo se buscó estudiar el efecto de la adición del ácido fuerte en el polímero, para ello se llevó a cabo la obtención por evaporación de solvente de diez complejos (de diferente composición entre Eudragit® E100 y ácido benzoico o ácido clorhídrico) y de cuatro ionómeros (sin el activo), a los cuales se les realizó análisis por FTIR y DSC. Los resultados demostraron la obtención de los respectivos complejos polielectro-lito y de los ionómeros; además los espectros de FTIR revelaron la relación directa entre la reacción de hidrólisis de los grupos ésteres del polímero y la proporción de HCl adicionada. Los termogramas, por su parte, evidenciaron la existencia de una reacción en el polielectrolito (PE), la cual se favoreció en aquellas composiciones en las que el proceso de hidrólisis ocurrió en mayor magnitud. El proceso de hidrólisis que se describe en el presente estudio debe tenerse en consideración en las futuras investigaciones en el campo, ya que su ocurrencia podría tener implicaciones en las diversas variables que se evalúan en este tipo de sistemas.

SUMMARY Polyelectrolyte complexes obtention between Eudragit® E100 (cationic polymer) and anionic molecules with additional neutralization of inorganic acids is a common practice in the development of these systems. In the present work the addition of strong acid effect on polymer structure was evaluated through FTIR and DSC analysis of a set of ten complexes with different composition (between Eudragit® E100 and benzoic acid) and four ionomers (without the preservative) obtained by solvent evaporation technique. Results demonstrated the complexes and ionomers formation. FTIR spectra revealed direct relationship between polymer ester groups hydrolysis reaction and the amount of HCl added. The thermograms, on the other hand, evidenced the existence of a reaction in the polyelectrolyte, which was favored in those compositions with more hydrolysis process. The degradation reaction described in this study should be taken into consideration in future research, since its occurrence could have implications in variables evaluated in this type of systems.

Formulation Optimization of Rutaecarpine Transdermal Patch / 中国药学杂志

OBJECTIVE: To screen pressure sensitive adhesive system and penetration enhancer of rutaecarpine transdermal patch. METHODS: The patch was prepared by solvent evaporation method. The ratio between pressure sensitive adhesive (Eudragit E100), crosslinking agent (succinic acid) and plasticizer (dibutyl sebacate) of the rutaecarpine patch were screened through Box-Behnken design by using adhesion (stick power, shear strength, peel force) as the index. The ratio between pressure sensitive adhesives and chemical enhancers (azone and oleic acid) were screened by adhesion and permeation experiments in vitro using custom design, which were carried out by using improved Franz diffusion cells through excised mice skin. RESULTS: The optimized formulation of rutaecarpine transdermal patch consisted of 83% pressure sensitive adhesives (63.5% Eudragit E100, 5.5% succinic acid, 14% dibutyl sebacate), 10% azone, 6.4% oleic acid and 0.6% rutaecarpine. The stick power, shear strength, and peel force of the patch were 15 steel balls, (10.97 ± 0.32) h and (0.16 ± 0.02) kN•M-1, respectively. The cumulative permeation amount and permeation rate of the patch were (29.71 ± 1.19) μg•cm-2 and (1.36 ± 0.10) μg•cm -2•h -1, respectively. CONCLUSION: The optimized rutaecarpine patch show increased permeation and appropriate adhesion. This study provides the basis for future research.

Preparation, Characterization and Dissolution of Solid Dispersion of Diclofenac Sodium Using Eudragit E-100.

Solis dispersions (SDs) traditionally have been used as effective methods to improve the dissolution properties and bioavailability of poorly water-soluble drugs. Diclofenac Sodium, a non steroidal anti-inflammatory drug with analgesic and anti-inflammatory property was selected as the model drug. The poor aqueous solubility of the drug results in variable dissolution rate and hence poor bioavailability. The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, diclofenac sodium, by SD technique as using Eudragit E100. SD was prepared by solvent evaporation technique. The SD was characterized for particle size, particle size distribution and solubility studies. Solid state characterizations i.e., Differential Scanning Calorimetry and Scanning Electron Microscopy were also carried out for the best formulation. It was concluded that the SD prepared by solvent evaporation technique using Eudragit E100 enhanced solubility and dissolution and hence better patient compliance and effective therapy.

Colonic delivery of film coated meloxicam tablets using natural polysaccharide polymer mixture.

Now days natural polysaccharides are extensively used for the development of solid dosage forms for delivery of drug to the colon. The objective of the present study was to develop a site-specific drug, single unit formulation allowing targeted drug release in the colon. Solid unit dosage forms were prepared using polysaccharides or synthetic polymer included xanthan gum, pectin, chitosan and Eudragit-E. Meloxicam was used as a model drug. The prepared tablets were enteric coated with Eudragit-S 100 to give protection in the stomach. The coated tablets were tested in-vitro for their suitability as colon specific drug delivery systems. The dissolution data so obtained illustrates that enteric coated tablets containing 3% chitosan as a binder, showed only 12.5% drug release in the first 5 h, which is the usual upper gastrointestinal transit time, whereas, tablets prepared using xanthan gum as binder, were unable to protect drug release under similar conditions. Solid formulations containing pectin as a binder formed time-dependent release formulations. 28% drug release was observed in the usual upper gastrointestinal tract conditions, when used in a concentration of 5.92% in the tablets.

Formulation and In-Vivo Study of Diltiazem Hydrochloride Tablets Prepared Using Interpolymer Complexes.

Aim: To investigate interpolymer complexes (IPCs) formation between carbopol and cationic polymers such as chitosan and Eudragit E for oral controlled drug delivery systems. Methodology: The prepared IPCs were investigated using Fourier transform infra-red spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Chitosan-carbopol and Eudragit E-carbopol IPCs loaded with diltiazem hydrochloride (DTZ HCl) with different drug:polymer ratios were also prepared. Diltiazem hydrochloride tablets were prepared using polymers alone, physical mixtures of chitosan or Eudragit E with carbopol and the corresponding drug loaded IPCs. In-vitro release studies were carried out in two dissolution media; 0.1 NHCl of pH 1.2 and phosphate buffer of pH 7.4. Results: The dissolution rate of DTZ HCl from the prepared tablets were found to be dependant on the interaction between chitosan or Eudragit E with carbopol in the physical mixture, drug:polymer ratio and pH of the dissolution medium. Tablets prepared using chitosan – carbopol IPC, Eudragit E – carbopol IPC, and Eudragit E – carbopol physical mixture of drug:polymer ratio 1:5 were selected for the in-vivo study using rabbits. The results showed a lower peak plasma concentration and marked prolonged release effect of tablets containing Eudragit E – carbopol IPC and the corresponding physical mixture compared to that of commercial Altiazem tablets. Conclusion: Tablets containing Eudragit E – carbopol or chitosan – carbopol physical mixtures showed prolonged drug release compared to that containing the corresponding IPCs, Furthermore, Eudragit E- carbopol matrix tablets showed slower drug release than that of chitosan – carbopol

Colonic delivery of film coated meloxicam tablets using natural polysaccharide polymer mixture.

Now days natural polysaccharides are extensively used for the development of solid dosage forms for delivery of drug to the colon. The objective of the present study was to develop a site-specific drug, single unit formulation allowing targeted drug release in the colon. Solid unit dosage forms were prepared using polysaccharides or synthetic polymer included xanthan gum, pectin, chitosan and Eudragit-E. Meloxicam was used as a model drug. The prepared tablets were enteric coated with Eudragit-S 100 to give protection in the stomach. The coated tablets were tested in-vitro for their suitability as colon specific drug delivery systems. The dissolution data so obtained illustrates that enteric coated tablets containing 3% chitosan as a binder, showed only 12.5% drug release in the first 5 h, which is the usual upper gastrointestinal transit time, whereas, tablets prepared using xanthan gum as binder, were unable to protect drug release under similar conditions. Solid formulations containing pectin as a binder formed time-dependent release formulations. 28% drug release was observed in the usual upper gastrointestinal tract conditions, when used in a concentration of 5.92% in the tablets.