Preparation of sustained-release dosage form of Venlafaxine HCl using liquisolid technique

Liquisolid systems as a novel approach in formulation and manufacturing of solid dosage forms: Challenges and perspectives

Liquisolid systems are a novel, promising platform for the production of solid dosage forms with a high liquid content, i.e. dispersion of the drug in a suitable, hydrophilic, non-volatile liquid vehicle or liquid drug. This technology requires conventional, but highly porous excipients (carrier and coating material in the appropriate ratio) able to absorb/adsorb liquid medication, resulting in both good flowability and acceptable compression properties. This approach has shown great potential to improve the dissolution rate and bioavailability of poorly soluble drugs, and has been recognized as a good alternative to common, more complex and expensive techniques. A variety of applications of this simple technique have been investigated recently, including the preparation of: modified release tablets, orally disintegrating tablets, solid dosage forms with liquid herbal extracts, etc. This emerging technology has numerous advantages, and the most important are: simplicity, cost-effectiveness, applicability in large scale production and environmental friendliness. However, it is accompanied by certain challenges as well, such as limited applicability in the case of highly dosed drugs. This article aims to give a comprehensive overview of recent progress regarding the potential applications of this technology, as well as to give an insight into the new liquisolid-based techniques intending to further support its commercial applicability.

Liquisolid Technology: A State-of-the-Art Review on the Current State, Challenges, New and Emerging Technologies for Next Generation

Nowadays, the focus has been shifted to new technologies for improving drug solubility, permeability, and bioavailability, amid unprecedentedly increasing the number of newly discovered Active Pharmaceutical Ingredients (APIs), which are mostly categorized under Biopharmaceutical Classification System (BCS) as class-II and class IV. Traditional technologies and classical formulation strategies often fail to address most of the formulation problems associated with new APIs, particularly solubility and bioavailability. Therefore, exploring new and innovative technologies on an industrial scale is a prerequisite and requires modernization of manufacturing processes, as well as more advanced research and development. Liquisolid technology is a new, innovative industrial technology, particularly designed for either improving the release rates of poorly absorbed drugs or controlling their release pattern by achieving sustained-release profiles with zero-order release kinetics. Besides, it is a promising photoprotective system for photosensitive drugs and can further be used for modulating the drug microenvironmental pH. The next generation of liquisolid systems stems from a set of emerging technologies, such as liqui-pellet technology, which originates from combining liquisolid technology with pelletization technique, particularly extrusion-spheronization technique. This review article highlights the current state of liquisolid technology, ongoing challenges, characterization and applications, possible future prospects, the advent of new and emerging technologies, and the revolution of the next generation of liquisolid technology.

The importance of the coating material type and amount in the preparation of liquisolid systems based on magnesium aluminometasilicate carrier

Albeit the preparation of liquisolid systems represents an innovative approach to enhance the dissolution of poorly soluble drugs, their broader utilization is still limited mainly due to the problematic conversion of the liquid into freely flowing and readily compressible powder. Accordingly, the presented study aims to determine the optimal carrier/coating material ratio (R value) for formulations based on magnesium aluminometasilicate (NUS2) loaded with polyethylene glycol 400. Four commercially available colloidal silica were used as coating materials in nine different R values (range of 5 - 100). The obtained results suggested that the higher R value leads to the superior properties of powder mixtures, such as better flowability, as well as compacts with higher tensile strength and lower friability. Moreover, it was observed that the type of coating material impacts the properties of liquisolid systems due to the different arrangement of particles in the liquisolid mixture. To confirm the noted dependency of R value and coating material type, the one- and two-way ANOVA, linear regression and principal component analysis (PCA) techniques were performed. In addition, a comparison of results with the properties of loaded NUS2 itself revealed that LSS with sufficient properties may be prepared even without the coating material.

Liquisolid technique and its applications in pharmaceutics

Most of the newly developed drug candidates are lipophilic and poorly water-soluble. Enhancing the dissolution and bioavailability of these drugs is a major challenge for the pharmaceutical industry. Liquisolid technique, which is based on the conversion of the drug in liquid state into an apparently dry, non-adherent, free flowing and compressible powder, is a novel and advanced approach to tackle the issue. The objective of this article is to present an overview of liquisolid technique and summarize the progress of its applications in pharmaceutics. Low cost, simple processing and great potentials in industrial production are main advantages of this approach. In addition to the enhancement of dissolution rate of poorly water-soluble drugs, this technique is also a fairly new technique to effectively retard drug release. Furthermore, liquisolid technique has been investigated as a tool to minimize the effect of pH variation on drug release and as a promising alternative to conventional coating for the improvement of drug photostability in solid dosage forms. Overall, liquisolid technique is a newly developed and promising tool for enhancing drug dissolution and sustaining drug release, and its potential applications in pharmaceutics are still being broadened.

Effect of solvent on retarding the release of diltiazem HCl from Polyox-based liquisolid tablets

Objectives

The aim of this work was to investigate the use of liquisolid technique to sustain the release of a model highly soluble drug, diltiazem HCl, from liquisolid matrices containing Polyox, a recently proposed matrix-forming hydrophilic polymer as an alternative to hypromellose.

Methods

Polyox-based liquisolid formulations prepared using several non-volatile solvents (i.e. polysorbate 80, polyethylene glycol, polyethylene glycol 200 and polyethylene glycol 600) and then characterised using differential scanning calorimetry and powder X-ray diffraction. The influence of solvent on retarding the release of diltiazem HCl from Polyox-based liquisolid tablets compared to conventional physical mixture tablets was studied.

Key findings

Liquisolid tablets exhibited greater retarding properties compared to conventional tablets. The use of polysorbate produced a slower release pattern of the drug from diltiazem hydrochloride (DTZ) liquisolid tablets compared to propylene glycol and polyethylene glycol (200 and 600). The release retardation was decreased with the increase in the concentration of the drug within drug:solvent liquid medication used. Solid-state analysis suggested the presence of a fraction of the drug mass in a solubilised state within polysorbate in liquisolid powders.

Conclusion

Polyox-based matrix tablets prepared using liquisolid technique in the presence of a carefully selected non-volatile solvent could produce desirable, more sustained release profiles of highly water-soluble drugs compared to conventional physical mixture tablets.