The Role of Functional Excipients in Solid Oral Dosage Forms to Overcome Poor Drug Dissolution and Bioavailability

Abstract

Many active pharmaceutical ingredients (APIs) exhibit poor solubility and low dissolution rates in aqueous environments such as the luminal fluids of the gastrointestinal tract. The oral bioavailability of these compounds is usually very low as a result of their poor solubility properties. In order to improve the bioavailability of these poorly soluble drugs, formulation strategies have been applied as a means to improve their aqueous solubility and dissolution rates. With respect to formulation approaches, excipients can be incorporated in the formulation to assist in the dissolution process of the drug, or specialized dosage forms can be formulated that improve dissolution rate through various mechanisms. This paper provides an overview of selected excipients (e.g., alkalinizing agents, surfactants and sugars) that can be used in formulations to increase the dissolution rate as well as specialized dosage forms such as self-emulsifying delivery systems and formulation techniques such as inclusion complexes and solid dispersions. These formulation approaches are discussed with available examples with specific reference to positive outcomes in terms of drug solubility and bioavailability enhancement.

Recycling of Almond By-Products for Intestinal Inflammation: Improvement of Physical-Chemical, Technological and Biological Characteristics of a Dried Almond Skins Extract

“…According to USP 37, ASE was considered practically insoluble in water (50.0 ± 1.5 mg/L) at room temperature, and the water dissolution test showed that no more than 45% of ASE dissolved in 45 min. These characteristics influence the in vivo active behavior, reducing its in vivo absorption and bioavailability [ 28 ]. For this reason, we considered CD as a material to improve ASE solubility and to enhance the dissolution rate [ 8 ].…”

Development of Remdesivir as a Dry Powder for Inhalation by Thin Film Freezing

“…It is known that certain drugs form a complex with Captisol ® by hydrophobic interactions [ 15 , 16 , 17 ]. The inclusion complexation between cyclodextrin and a drug can generally increase the aqueous solubility of the aforementioned drug, and increase the dissolution rate [ 54 ]. It was previously reported that the solubility of remdesivir can be increased by Captisol ® , and Veklury ® , and the commercial product containing remdesivir includes Captisol ® to solubilize remdesivir for the IV solution formulation [ 15 ].…”

Development of Remdesivir as a Dry Powder for Inhalation by Thin Film Freezing

“…It is known that certain drugs form a complex with Captisol® by hydrophobic interactions [15][16][17]. The inclusion complexation between cyclodextrin and drug can increase the aqueous solubility of drug, and increase the dissolution rate [49]. It was previously reported that the solubility of remdesivir can be increased by Captisol®, and Veklury®, the commercial product containing remdesivir, includes Captisol® to solubilize remdesivir for the IV solution formulation [15].…”