Pharmaceutical excipients are core components of medicinal preparations. They are widely used in the production and formulation of various dosage forms, directly influencing a drug's formability, stability, safety, and efficacy. Their primary application scenarios include:
Oral Solid Dosage Forms
This is the most extensive area of application for pharmaceutical excipients, encompassing common dosage forms such as tablets and capsules:
Fillers (Diluents): Substances like starch, lactose, and mannitol are used to increase the volume of a formulation, addressing the challenge of processing active ingredients that are present in very small doses.
Functional Excipients: Magnesium stearate acts as a lubricant to reduce friction during manufacturing; crospovidone serves as a disintegrant, facilitating the rapid breakdown of the drug within the body; and various cellulose derivatives function as binders, ensuring that powder particles adhere firmly together.
Specialized Functional Excipients: Coating materials can protect drugs from light or mask unpleasant tastes. Certain enteric coatings allow for drug release at specific locations within the intestinal tract, preventing degradation by gastric acid.
Injectable Preparations
Injectable formulations impose extremely high safety standards on excipients, as these components directly impact the safety of drug administration:
Solubilizing/Co-solubilizing Systems: Polysorbate 80 (Tween 80) is frequently used as a solubilizer in traditional Chinese medicine (TCM) injections, while substances like ethanol, propylene glycol, and glycerol serve as co-solvents to enhance the solubility of poorly soluble drugs.
Stabilizing and Adjusting Excipients: Sulfites and vitamin C act as antioxidants to prevent oxidative degradation, while sodium chloride functions as an osmotic pressure adjuster, ensuring the injection is isotonic with human blood.
Specific Restrictions: Injections intended for intravenous use require specialized excipients, such as phospholipids or poloxamer 188. Furthermore, injections intended for intravenous or intraspinal (intrathecal) administration generally must not contain bacteriostatic agents (preservatives).
