Article

Improvement of physicomechanical properties of carbamazepine by recrystallization at different pH values.

Faculty of Pharmacy and Drug, Applied Research Centre, Tabriz University of Medical Sciences, Tabriz 51664, Iran.
Acta Pharmaceutica (Impact Factor: 1.03). 07/2009; 59(2):187-97. DOI: 10.2478/v10007-009-0015-x
Source: PubMed

ABSTRACT The morphology of crystals has an appreciable impact role on the physicochemical properties of drugs. Drug properties such as flowability, dissolution, hardness and bioavailability may be affected by crystallinity behaviours of drugs. The objective of this study was to achieve an improved physicomechanical property of carbamazepine powder through recrystallization from aqueous solutions at different pH values. For this purpose, carbamazapine was recrystallized from aqueous solutions at different pH values (1, 7, 11). The morphology of crystals was investigated using scanning electron microscopy; X-ray powder diffraction (XRPD) was used to identify polymorphism; thermodynamic properties were analyzed using differential scanning calorimetery (DSC). Dissolution rate was determined using USP dissolution apparatus. Mechanical behavior of recrystallized carbamazepine powders was investigated by making tablets under different compaction pressure and measuring their hardness. SEM studies showed that the carbamazepine crystallization in different media affected the morphology and size of carbamazepine crystals. The shape of carbamazepine crystals changed from flaky or thin plate-like to needle shape. XRPD and DSC results ruled out any crystallinity changes occurring due to the temperature during recrystallization procedure or pH of crystallization media. The crushing strength of tablets indicated that all of the recrystallized carbamazepine samples had better compactiblity than the original carbamazepine powder. In vitro dissolution studies of carbamazepine samples showed a higher dissolution rate for carbamazepine crystals obtained from media with pH 11 and 1. Carbamazepine particles recrystallized from aqueous solutions of different pH values (all media) appeared to have superior mechanical properties to those of the original carbamazepine sample.

0 Bookmarks
 · 
225 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: We evaluated the effects of the sample feeding and mixing methods on the efficiency of vancomycin crystallization and developed a method to dramatically shorten the time required for crystal formation by increasing the available surface area inside the reactor. The highest purity (97%) and yield (99%) of vancomycin could be obtained with an initial one-step feeding and mixing method, resulting in the formation and growth of spherical fan-shaped crystals. The yield of vancomycin increased when the surface area per working volume (S/V) was increased to 0.428mm−1 using glass beads (0.5mm), the cation exchange resin Amberlite 200, or the anion exchange resin Amberlite IRA-400. In particular, most of the vancomycin (>99%) could be recovered after 6h of crystallization using Amberlite 200, resulting in a dramatic reduction in the time required for crystallization. On the other hand, increasing S/V had almost no effect on vancomycin purity and crystal size.
    PROCESS BIOCHEMISTRY 10/2011; 46(10):2068-2073. · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Self-assembled one dimensional pharmaceutical solids composed of caffeine, carbamazepine and glibenclamide drugs exhibit optical wave guiding tendency due to efficient two dimensional lateral optical confinement effect. 10 Additionally, the confined optical waves within the tubes were used to probe the nano-/micro scale defect sites inherited during the tubes self-assembly process via Raman spectroscopy.
    CrystEngComm 02/2014; · 3.86 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study describes the evaluation and optimization of a crystallizing process capable of efficiently purifying vancomycin in high purity and yield. In particular, we observed how the main process parameters influenced the formation of crystals, determined their morphology, and monitored purity and yield. Acetone was shown to be more effective than alcohol solvents for the crystallization of vancomycin. The optimal distilled water/acetone ratio, storage temperature, storage time, pH, conductivity, initial vancomycin concentration and stirrer velocity were shown to be 1: 3.5 (v/v), 10 °C, 24 h, pH 2.5, 20 ms/cm, 0.1 g/mL, and 640 rpm, respectively. Temperature had a decisive influence on crystal formation; crystals were successfully produced at 10 °C, while at other temperatures, conglomeration, disintegration and cohesion occurred. Crystal growth developed over time and was complete at about 24 h. Vancomycin purity remained at about 97.0% irrespective of storage time while the yield increased over time, reaching a maximum of 95.0% at around 24 h, after which there was no substantial change. Crystallization occurred over a certain range of pH (2.5–3.0), but purity and yield were highest at pH 2.5. When the pH was outside this range, a conglomeration (gelation) phenomenon prevented the efficient production of crystals. Vancomycin crystals were produced irrespective of the stirrer velocity, which had no influence on purity; however, the highest yield of vancomycin was obtained at 640 rpm. Key wordsVancomycin-Crystallization-Purification-Optimization of Process Parameters-Identification of Morphology
    Korean Journal of Chemical Engineering 09/2010; 27(5):1538-1546. · 1.24 Impact Factor

Full-text (2 Sources)

Download
75 Downloads
Available from
May 23, 2014