The liquisolid technique is a novel approach for delivery of drugs through the oral route. This technique is suitable for poorly soluble or water insoluble drugs, highly permeable drugs (BCS Class II drugs) and also for immediate or sustained release formulations. It is a novel "Powder Solution Technology" that involves absorption and adsorption efficiencies, making use of liquid medications, drug suspensions admixed with suitable carriers, coating materials and formulated into free flowing, dry looking, non-adherent and compressible powder forms. The design of liquisolid systems are mainly intended for enhancement of solubility, dissolution rate and bioavailability of poorly water-soluble and highly lipophilic drugs. Improvement in bioavailability may be due to increased surface area, increased aqueous solubility and increased the wettability of the drug. Liquisolid technique also has the potential to be optimized for the reduction of drug dissolution rate and thereby production of sustained release systems. Overall, liquisolid technique is a most promising and novel technique for enhancing the dissolution and bioavailability of poorly water soluble drugs and sustaining drug release from tablet matrices. The current review mainly focuses on theory and applicability of liquisolid compact technique towards solubility or bioavailability enhancement. Different carriers, solvents and coating materials employed are elucidated. Literature reports on the applicability of liquisolid compact techniques over a wide range of pharmaceutical formulations are also explicated.

The present study was aimed to formulate, develop and evaluate the fast dissolving tablets of diclofenac sodium, used for the treatment of arthritis, inflammation, pain. Fast dissolving tablets of diclofenac sodium were prepared by direct compression method using crospovidone and sodium starch glycolate as superdisintegrants in concentrations of 5.3%, 6.6% and 8% w/w and in combination. In this work microcrystalline cellulose and mannitol are investigated as diluents. Prepared powder mixtures were evaluated for drug excipient compatibility with FTIR spectroscopy and DSC analysis. Prepared formulations are evaluated for In vitro dissolution, disintegration dispersion and wetting time. Formulation FCS6 prepared with combination of crospovidone and sodium starch glycolate at weight ratio of 6.6 and 2.3% showed better results compare with control. Post compression parameters like hardness (3.4 kg/cm 2 ) and friability (0.31%) are at good acceptable levels in accordance with official compendia. FCS6 showed improved dissolution (99.8 %) and dispersion (75 seconds) profiles compared to control. The FTIR and DSC showed no interaction between the drug and excipients. The optimized formula FCS6 showed good drug release characteristics with acceptable mouth feel and fast dissolving properties.

Poor aqueous solubility and slow dissolution rate adversely affects bioavailability of pioglitazone hydrochloride. This study was undertaken to improve dissolution and bioavailability of pioglitazone hydrochloride through preparation of stable solid dispersions by melting and solvent evaporation method using Solutol HS 15. Solubility of pioglitazone hydrochloride was enhanced by 9 to 49 fold as the drugcarrier ratio was increased in solid dispersions as compared to pure drug. Furthermore, compared to pure drug or physical mixture, solid dispersions significantly improved the dissolution rate and the extent of drug release. Solid dispersions at 1:7 drug:Solutol HS 15 weight ratio showed complete and rapid drug release within 15 min at pH 1.2. The Fourier-transform infrared spectrum revealed the chemical compatibility with Solutol HS 15. Differential scanning calorimetry and X-ray powder diffraction pattern revealed a change in crystallinity to amorphous state that supported the enhancement of solubility of pioglitazone hydrochloride with Solutol HS 15. In vivo test showed that Solutol HS 15-based solid dispersions showed higher AUC 0-t and C max , which was ~4 times higher than that of pure pioglitazone (p<0.05) implying solid dispersions could be effective in increasing the bioavailability. In conclusion, solid dispersions with Solutol HS 15 prepared using solvent evaporation method appeared to be a promising technique to improve the dissolution, bioavailability and stability of pioglitazone hydrochloride.

Swain, et al.: Gastro-bilayer Floating Tablets of Simvastatin and AtenololCombination therapy is highly desired to deliver atenolol and simvastatin for dyslipidemia and hypertension as a concomitant drug treatment. On other hand, atenolol has poor absorption in lower gastrointestinal tract, short half-life and simvastatin has poor solubility. Therefore, the present study was to develop gastro-bilayer floating matrix tablet in which simvastatin was incorporated as immediate layer and atenolol as sustained release layer. Gastro-bilayer floating tablets were prepared by direct compression method and optimized using hydroxypropyl methylcellulose K100 (37.5% w/w) as release retardant and sodium bicarbonate as a gas-forming agent. The immediate release layer comprised sodium starch glycolate as superdisintegrant. The tablets of optimized formulations floated on the test medium for more than 12 h with 9 min of floating lag time. Atenolol release was sustained for 12 h via diffusion mechanism and more than 96% release of simvastatin within 15 min was achieved. It can be concluded that, the biphasic drug release pattern was successfully achieved through the formulation of gastro-floating bilayer tablets in this study, allowing strengthened combination therapy for hypertension and dyslipidemia.

This study was undertaken to improve solubility and bioavailability of nateglinide by preparation of stable self-emulsifying solid dispersions (SESDs). The influence of semicrystalline polymers (poloxamer 407, gelucire 50/13) and method of preparation on dissolution behavior, in vivo performance and stability of nateglinide SESDs were investigated. After optimization, SESDs were prepared at 1:5 weight ratio of nateglinide and polymer individually. All the SESDs were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and scanning electron microscopy. Aqueous solubility of nateglinide was enhanced by 91.82-fold. The SESDs (poloxamer 407-based solid dispersions) achieved rapid and complete drug release (∼100% within 45 min) at pH 2. The improved dissolution appeared to be well correlated with the enhanced bioavailability of nateglinide in rabbits. After oral administration of SESDs (poloxamer 407-based solid dispersions), C and AUC of nateglinide were increased by ∼2.92 and 1.77-folds, respectively, signifying the effectiveness of solid dispersions to improve the bioavailability of nateglinide. Stability during storage was established to show prevention of recrystallization. In conclusion, SESDs with poloxamer 407 in solvent method appeared to be an economic and promising technique to improve the dissolution, bioavailability, and stability of nateglinide.

Introduction: Combination therapy of ezetimibe and atenolol is highly desirable for better management of dyslipidaemia and hypertension. Ezetimibe has poor solubility hence variable and low bioavailability. Atenolol has poor absorption in lower gastrointestinal tract, short half-life. Therefore, the present study was to develop gastro-bilayer floating matrix tablet in which ezetimibe was incorporated as immediate layer and atenolol as sustained release layer. Methods: Solubility of the ezetimibe was enhanced by solid dispersion technique and was characterized by FTIR, DSC and XRD study. Gastrobilayer floating tablets were prepared by direct compression method. Results and Discussion: Hydroxypropyl methylcellulose K100 (37.5 % w/w) as release retardant and croscarmellose sodium (15 % w/w) as superdisintegrants in immediate layer as optimized. The total floating time of the optimized tablet was 12 h with 9 min of floating lag time. Atenolol release was sustained through diffusion mechanism over 12 h and more than 95 % ezetimibe was released within 30 min. Conclusion: It can be concluded that biphasic drug release pattern was successfully achieved through the formulation of gastro-floating bilayer tablets in this study, allowing strengthened combination therapy for hypertension and dyslipidemia.

10 mg pioglitazone HCl dissolved in 10 mL of acetonitrile. From the standard stock pipette out in to 10 mL volumetric flasks and make up to 10 mL with blank plasma to get final concentrations of 0.5, 1, 5,10, 20, 40, 60 and 80 µg/mL.

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