**2. Liquisolid technology**

In order to create a "liquisolid powder system," a non-volatile solvent is first used to prepare either a lipophilic liquid medication or a drug solution/suspension of a water-insoluble or poorly aqueous soluble drug. This substance is referred to as "liquid medication." Additionally, it is transformed into easily compressible and freely flowing powders by mixing with excipients such carrier and coating ingredients. Liquid medication is combined with a carrier material (Avicel PH 102) having good absorption properties and coating material (Aerosil 200) having high adsorptive properties to obtain non-sticky, free-flowing readily compressible powder. It is further mixed with disintegrants to form immediate release compacts. The liquisolid (LS) powder can be further transformed to conventional solid dosage forms in which they can be compressed to compacts or encapsulated into hard gelatin capsules. The compacts so obtained are termed as liquisolid compacts (LSCs). Increased solubility, wettability, and drug surface area accessible for dissolution from the LSCs are thought to be the causes of the increased drug release rates [4]. However, the features of the medication and the different excipients employed in the formulation play a major role in determining the drug release profile. Therefore, using the LS approach, formulations that may either accelerate or delay the release of the medicine can be created by changing any one of these excipients. The novelty of the current study is application of liquisolid technique for the preparation of drug loaded tablets known as liquisolid

*Development of Liquisolid Compacts: An Approach for Dissolution Enhancement of Poorly… DOI: http://dx.doi.org/10.5772/intechopen.108706*

compacts, which showed higher drug release profiles compared to that of directly compressed tablets, especially in case of poorly aqueous soluble drugs.

#### **2.1 Constitution of LS formulation**

The LS formulations contain some key constituents such as


#### *2.1.1 Non-volatile solvent*

The non-volatile solvents should be able to solubilize the lipidic drug to the greatest extent, be inert, have a high boiling point, be water-miscible by nature, and not be excessively viscous. In the LS formulation, these hydrophilic solvents serve as a binding agent. Propylene glycol (PG), polysorbate 80, and polyethylene glycol (PEG) are a few examples of hydrophilic non-volatile solvents that are employed in LS formulations [5].

#### *2.1.2 Carrier materials*

The majority of liquid absorption is facilitated by carrier materials, which are typically porous materials with great absorption capabilities. These can maintain appropriate flow and compression properties while containing only a limited or fixed volume of solvent. However, an excessive rise in the carrier material's moisture content causes a deterioration in the powder flow properties. Various MCC grades, such as Avicel PH 101, PH 102, and PH 200, are examples of carrier materials [6].

#### *2.1.3 Coating materials*

The coating materials should have tiny, highly adsorbent particles that help to cover the wet surface of the carrier particles and retain the powder's flowability. Finally, complete adsorption of surplus liquid results in non-adherent, dry-looking powder. It is necessary to coat the surface with coating ingredients such as lactose, starch, syloid, aerosil 200, and silica (Cab-O-Sil M520) [2]. In addition to these, new coating materials with high adsorbent qualities as Sylysia (amorphous silica gel) and Neusilin (magnesium aluminum metasilicate) can also be employed.

#### *2.1.4 Additives*

It appears that the release of the drug is influenced by the process of disintegration of solid dosage forms. Therefore, disintegrants are typically added to LSCs to enable rapid disintegration. Examples of super disintegrants are low substituted hydroxypropyl cellulose (HPC), cross carmellose sodium, starch glycolate sodium, and crosspovidone [7]. In some instances, LS systems that typically function as a release retarding agent are supplemented with an additive called HPMC in order to

**Figure 1.** *Diagrammatic representation of formation of LS system.*

prolong medication release [8]. **Figure 1** depicts the diagrammatic picture of the creation of the LS system.
