Toimeaine

Toimeaine is the component of a medicinal product that produces the intended therapeutic effect. It may be a single chemical substance or a combination of substances in a fixed-dose product. The term distinguishes the active principle from excipients, which are carriers, fillers, stabilizers, or flavors that do not contribute to the pharmacological action.

In pharmacology, the properties of the active ingredient—such as its potency, dose, and bioavailability—determine a medicine’s efficacy and safety. The specific amount of the active ingredient is defined in the product’s specification (the strength) and is listed on the label. Medicines may contain one or more active ingredients, which can interact to achieve the desired therapeutic outcome.

Naming and regulation: Active ingredients are often referred to by an International Nonproprietary Name (INN). Regulatory authorities require standardized identification of active ingredients to ensure quality control, pharmacovigilance, and safety monitoring. Pharmacopoeias set standards for the purity, impurities, and analytical methods used to test active ingredients.

Examples include paracetamol, ibuprofen, and amoxicillin, which are commonly used active ingredients in various medicines. In multi-component formulations, several active ingredients may be present. The concept of a sole or multiple active ingredients is applicable across human medicines and veterinary products, with regulatory requirements varying by jurisdiction.

In Estonia, the term toimeaine is used to denote the active ingredient, and it is regulated within national frameworks by the Estonian Medicines Agency (Ravimiamet) under EU pharmacovigilance and pharmaceutical regulations.