ABSTRACT
Karaya gum (KG) is one of the least soluble of the gums. It does not dissolve in water to give a clear solution but instead absorbs water rapidly to form viscous colloidal sols. Carboxymethylation of Karaya gum is expected to improve its aqueous solubility and gelling behavior. Another objective of the research is to evaluate the potential of carboxymethylated Karaya gum (CMKG) as drug release modulator (in acidic dissolution medium) when combined with HPMC K15M based polymeric matrices bearing Propranolol HCl. In the present study, KG was carboxymethylated using Williamson Ether synthesis. FTIR spectroscopy confirmed the formation of CMKG. The prepared CMKG was used in conjunction with HPMC K15M as a polymer matrix in the formulation capsule dosage form, using Propranolol HCl as model drug. The filled capsules were then coated with Gelucire 43/01 to convert them into hydrodynamically balanced (HBS) capsule dosage form. Dextrose & fructose were also added to the drug-polymer mix as osmogen to facilitate the drug release. The degree of substitution of CMKG was found to be 0.87. HBS capsule dosage forms remained buoyant on 0.1 HCl for up to 6 hr, the buoyancy was attributed to the Gelucire 43/01 coating around the capsule shell. From the experimentation it was observed that CMKG, when mixed with HPMC K15M at 1:3 ratios, extended the release of model drug from HBS capsule dosage forms in 0.1 HCl. At CMKG: HPMC K15M ratio 2:1, release of Propranolol Hydrochloride from hydrodynamically balanced (HBS) capsules revealed fast drug release in 0.1 HCl. From the observations it is evident that KG is amenable to carboxymethylation to form CMKG. It is also evident that it is advantageous to combine CMKG with HPMC K15M as release modulator to retard the release of Propranolol HCl in acidic dissolution medium.
ABSTRACT
The objective of the present study was to develop a solid dispersion formulation to improve oral bioavailability of poorly water-soluble drug carvedilol. Several solid dispersions were prepared by fusion-solvent method mixing different concentrations of Gelucire 44/14 and Gelucire 50/13. To the resultant solid dispersions, microcrystalline cellulose and amorphous fumed silica were added to obtain a free-flowing powder. The dissolution of carvedilol was evaluated using an USP Type-II dissolution apparatus. Solid dispersion with Gelucire 44/14 showed, in general, a lower extent of drug release when compared to Gelucire 50/13 at the same concentrations. Gelucire 50/13 in a ratio of 1 to 1.75 (drug: Gelucire) achieved a drug release of 83% in 4 hours, a 5-fold increase compared to pure carvedilol. When incorporating 10% D-α-tocopheryl polyethylene glycol succinate (vitamin E TPGS/ TPGS) a higher drug release was observed (88%). Parallel artificial membrane permeability assay was used to evaluate the in vitro diffusion. GelucireTPGS solid dispersion showed a higher permeability coefficient compared to pure drug. After oral administration to Sprague-Dawley rats, a significant increase in the oral bioavailability of carvedilol was observed when administered as a solid dispersion in combination with Gelucire-TPGS, 169% higher compared to pure drug suspension.
ABSTRACT
The objective of the present investigation was to design and optimize lipid-based floating multiparticulate of Berberinehydrochloride (BERH), so as to increase its solubility and to reduce P-Glycoprotein mediated efflux in the intestine,hence to improve oral bioavailability. Solid dispersions were prepared using hydrophilic carriers gelucire 44/14and gelucire 50/13 in different ratio. The prepared solid dispersion of BERH was further formulated into sustainrelease gastroretentive floating pellets using hydrophobic lipid carrier gelucire 43/01 as release retardant, sodiumbicarbonate (NaHCO3) and hydroxylpropyl methyl cellulose K4M (HPMC K4M) as gas former and matrix polymer,respectively. The effect of amount of gelucire 43/01 and NaHCO3: HPMC K4M were studied and optimized using a3-level, 2-factor, factorial design. Solid dispersion of BERH compared to pure drug showed 4-fold enhancement inaqueous solubility. The optimum system could float for more than 8 hours and showed 88.46% drug release in 8 hours.The pharmacokinetic study conducted in male Wistar rats indicated 2.32-fold increase in relative bioavailability ofoptimized formulation compare to the marketed tablet. The lipid-based floating pellets of BERH were obtained andcould be an applicable choice to deliver BERH with improved bioavailability in effective use for various clinicalapplications.
ABSTRACT
Clonazepam (CLZ) is an anticonvulsant benzodiazepine widely used in the treatment of epilepsy. CLZ is a BCS Class II drug and its bioavailability is thus dissolution limited. The objective of the present study was to prepare solid dispersions (SDs) of CLZ by various techniques, using the amphiphilic carrier Gelucire 50/13 in various proportions, to increase its water solubility. Drug-polymer interactions were investigated by Fourier-transform infrared (FTIR) and Ultra-Violet (UV) spectroscopy. The SDs were characterized physically by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). A phase solubility study was performed and the stability constant (Ks) was found to be 275.27, while the negative Gibbs free energy (?Gotr) indicated spontaneous solubilization of the drug. The dissolution study showed that the SDs considerably enhanced the dissolution rate of the drug. The FTIR and UV spectra revealed no chemical incompatibility between the drug and Gelucire 50/13. XRD patterns and the DSC profiles indicated the CLZ was in the amorphous form, which explains the improved dissolution rate of the drug from its SDs. Finally, mouth dissolving tablets (MDTs) were prepared from the optimized batches (kneading method) of solid dispersion, using crospovidone and Doshion P544 resin as superdisintegrants. The tablets were characterized by in-vitro disintegration and dissolution tests. The study of the MDTs showed disintegration times in the range 32.0±0.85 to 20.0±1.30 sec and dissolution was faster than for the commercial preparation. In conclusion, this investigation demonstrated the potential of solid dispersions of a drug with Gelucire 50/13 for promoting the dissolution of the drug and contributed to the understanding of the effect of a superdisintegrant on mouth dissolving tablets containing a solid dispersion of a hydrophobic drug.