Physical Drug-excipient Interactions Studies

Pharmaceutical excipients are involved in various drug-excipient interactions, which significantly affect the the performance of final products. An understanding of the mechanisms that form these interactions is critical to the design of robust drug products. Physical interactions do not involve any chemical changes, and can be categorized as non-covalent including van der Waals forces (or dispersion forces), hydrogen bonding, and noncovalent(forces), hydrogen bonding, and electrostatic interactions (also known as ionic bonding). Proper characterization of excipient-drug interactions using physical and chemical methods is useful in determining the compatibility of target APIs with excipients. Comprehensive investigation of excipient interaction has become essential knowledge for rational formulation design, BOC Sciences therefore provides services of physical drug-excipient interaction studies.

Application

• Optimize the critical properties of excipients
• Improve the bioavailability of drugs
• Adjust key process parameters or formulation parameters

Figure 1. Drug Excipient Interactions. (Narang, A. S.; et al. 2015)

What We Offer?

Physical interactions occur mainly in three forms: complexation, adsorption, or solid dispersions. At BOC Sciences, we perform the investigation of these physical interactions to assist in different dosage forms design.

Assessment of Adsorption Behavior

Adsorption between the drug and excipients occurs on the surface of the drug, and the adsorption phenomenon may have some negative effects, such as preventing the aggregation of the drug through the excipients to form a film on the surface of the active drug substance, which affects the stability (reducing the dissolution rate of the drug) and the efficiency (bioavailability) of the drug. BOC Sciences has introduced a variety of thermal analysis techniques to determine the physical interaction. In addition, in order to further observe this interaction, microscopy and spectroscopy instruments are employed to characterize and evaluate the adsorption behavior between APIs and excipients.

Assessment of Complexation

The complexing agent in a formulation is usually able to reversibly interact with the drug to form a complexation. The active pharamceutical component in the complexation is not free to dissolve, as it must first dissociate from the complexation. Only after contact with gastrointestinal fluid does the drug complexation dissociate, releasing the drug substance, which is then absorbed across the gastrointestinal membranes. Therefore, complexation of APIs with highly soluble excipients is a common strategy used to improve the solubility of drugs. The experts at BOC Sciences offer API-excipient complexation testing services to help ensure excellent compatibility between your drug substance and excipient materials.

Assessment of Drug-excipient Interactions in Solid Disperstion

Solid dispersions refer to the dispersion of one or more active ingredients in an inert carrier. In the pharmaceutical industry, amorphous drugs can be formulated into asmicroscale solid dispersions by multiple manufacturing processes such as spray drying, freeze drying or hot melt extrusion, where the drug is stabilized by polymeric excipients. Solid dispersions can reduce the molecular mobility of the dispersed drug and thus enhance the release of the drug. We offer spectroscopic analysis services to observe the phase behavior between drug and excipients, and to determine if drug-excipient interactions are formed in the solid dispersion. In addition, the stability of the drug-excipient complexations is further evaluated by using the thermal tools.

Figure 2. Surface interaction between drug and excipient in binary mixture. (Nv, A.; et al. 2022)