Author: Ram Kumar Sahua Jiyauddin Khanb
Poorly water-soluble drug, approximately 6070% of the drug molecules are insufficiently soluble in aqueous media and/or have very low permeability to allow for their adequate and reproducible absorption from the gastrointestinal tract (GIT) following oral administration, Formulation scientists have to adopt various strategies to enhance their absorption, self-emulsifying systems, scientists to transform the liquid self-emulsifying drug delivery systems (SEDDS) to solid-SEDDS by adsorption, spray drying, lyophilization, melt granulation, extrusion, and so forth to formulate various dosage forms like self-emulsifying capsules, tablets, controlled release pellets, beads, microspheres, nanoparticles, suppositories, implants, deliver new drug molecules with enhanced bioavailability mostly exhibiting poor aqueous solubility, It is estimated that between 40% and 70% of all new chemical entities identified in drug discovery programs are insufficiently soluble in aqueous media, the increase in the proportion of poorly soluble candidates is frequently attributed to improvements in synthesis technology, which has enabled the design of very complicated compounds, and a change in discovery strategy from a so-called phenotypic approach to a target-based approach, Various physicochemical properties which contribute to the poor solubility of various drugs include their complex structure, size, high molecular weight, high lipophilicity, compound H-bonding to solvent, intramolecular H-bonding, intermolecular H-bonding (crystal packing), crystallinity, polymorphic forms, ionic charge status, pH, and salt form, drug for absorption can be enhanced by formulation of the drug as a solubilized within a colloidal dispersion, hydrophobic drugs is well documented in the literature. These generally consist of a drug dissolved in a blend of excipients (5 classes of excipients) with wide variety of physicochemical properties ranging from pure triglyceride oils, mono- and diglycerides, and substantial proportion of lipophilic or hydrophilic surfactants and cosolvents, enhanced oral bioavailability enabling reduction in dose, more consistent temporal profiles of drug absorption, selective targeting of drug(s) toward specific absorption window in GIT, and protection of drug(s) from the hostile environment in gut, Types of Self-Emulsifying Systems: Self-Emulsifying, Self-Microemulsifying, and Self-Nanoemulsifying Drug Delivery System, unit dosage form in soft or hard gelatin capsules due to the anhydrous nature, increase the intestinal permeability and minimize the effect of pH on drug absorption, degree of participation of the portal venous and mesenteric lymphatic pathways in overall drug absorption, Selection of Excipients in Self-Emulsifying Formulations, surfactants may improve the affinity between lipids and intestinal membrane or increase the permeability of the intestinal membrane. Surfactants increase the permeability by partitioning into the cell membrane and disrupting the structural organization of the lipid bilayer leading to permeation enhancement, most drugs are absorbed via the passive transcellular route, absorption enhancing effects by increasing the dissolution rate of the drug, avoid amount of solidifying excipients may affect the release of the drug, nature of the excipients used may affect the drug absorption, probability of irreversible phase separation on reconstitution, clogging of spray nozzles due to oil content in spray-drying method, degradation of drug during solidification process, reduction in drug loading capacity, difficulty in ensuring content uniformity, (8) Probability of residual solvents used during granulation, Capsule filling is the simplest and the most common technology for the encapsulation of liquid, semisolid, or solid SE formulations for the oral route, aloe vera gel can help in unfavourable physicochemical properties for their drug absorption in the body
