Excipients

Excipients are inactive substances formulated with the active pharmaceutical ingredient (API) to create a finished dosage form. They do not have therapeutic effects themselves but support manufacturing, stability, delivery, and usability of a drug product. Excipients can influence solubility and dissolution, shelf life, taste and odor, appearance, and dosing accuracy, and may affect the bioavailability of the API.

Common categories include fillers or diluents (lactose, microcrystalline cellulose) to add bulk; binders (povidone, hydroxypropyl cellulose) to help tablet formation; disintegration agents (crospovidone, starch) to promote breakup in the GI tract; lubricants (magnesium stearate) to reduce sticking; glidants (silica) to improve powder flow; film or enteric coatings (hypromellose, polyvinyl acetate phthalate) to protect the drug or control release; surfactants and emulsifiers to improve solubility; antioxidants, stabilizers, and preservatives to preserve product quality; colorants and flavoring agents to aid identification and palatability; tonicity-adjusting agents (sodium chloride, dextrose) for parenteral or ophthalmic solutions.

In parenteral, oral, topical, and inhalation products, excipients are chosen to support stability, compatibility with the API, patient safety, and the desired route of administration. Regulatory agencies and pharmacopoeias provide standards, and manufacturers apply good manufacturing practices to ensure purity and consistency. The selection of excipients depends on the dosage form, stability of the API, patient needs, and manufacturing considerations.