3.18 : Factors Influencing Drug Absorption: Pharmaceutical Parameters

Solid dosage forms such as tablets and capsules undergo rigorous manufacturing processes to ensure stability and effectiveness. Their dissolution and absorption properties are influenced significantly by the choice of excipients (inactive ingredients that serve various roles in the formulation), and the methodology applied during production. The manufacturing parameters, such as compression force and granulation techniques, significantly affect dissolution rates. Elevated compression forces contribute to a higher tablet density, negatively impacting wettability while augmenting structural integrity, thereby decelerating dissolution. The formulation often includes excipients that stabilize the product, enhance functionality, and ensure optimal bioavailability. These excipients range from vehicles and diluents, which facilitate the drug's incorporation into the systemic circulation, to disintegrants and surfactants, which foster tablet disintegration and lower the surface tension between two ingredients to make them more miscible, respectively. The strategic employment of binders adds cohesion to powders to allow tablets to stick together, whereas lubricants minimize intergranular friction and help keep ingredients from sticking together.

Considering these excipients' hydrophilic or hydrophobic nature is imperative, as their interaction with the drug substance can profoundly impact dissolution characteristics. For instance, hydrophilic diluents enhance the dissolution of hydrophobic drugs, while hydrophobic binders and lubricants might hinder this process.