Definition
Active ingredients are the active components of a drug that are responsible for its pharmacological effects. Drugs may contain a single active ingredient, multiple active ingredients, or complex mixtures such as herbal extracts. In addition to the active ingredients, a drug contains various excipients that should be as pharmacologically inert as possible. The percentage of excipients often exceeds that of the active ingredients.
Active ingredient types
Most active ingredients today are low-molecular-weight, chemically unambiguously defined compounds with molecular masses ranging from about 200 to 600 g/mol. Typical examples include losartan, metoprolol, and escitalopram. Such substances were first produced in the 19th century. Early synthetic active ingredients include, for example, acetylsalicylic acid (aspirin) and phenazone (antipyrine). Active ingredients are also isolated from natural sources. For example, the opioid and alkaloid morphine was first extracted from opium at the beginning of the 19th century. In this context, one also speaks of pure substances. These can be semisynthetically modified. In addition to organic molecules, inorganic substances such as the salts are also active ingredients. Plant extracts (phytopharmaceuticals) are also referred to as active ingredients. They are multi-substance mixtures consisting of hundreds of substances. Finally, biologics, for example, proteins, enzymes, receptors, monoclonal antibodies, cells, gene therapeutics, and therapeutic viruses, are also considered active ingredients.
Origin
Many of the agents developed in the 20th century have a natural origin or are derived from natural products. For example, active compounds have been extracted from plants or fungi for use as drugs. Numerous derivatives have also been produced from these compounds. Active substances from the human body have also played an important role, such as hormones (e.g. insulin, levothyroxine, adrenaline, glucocorticoids) or neurotransmitters (serotonin, dopamine, noradrenaline). Today, most of the active ingredients are synthesized artificially.
Exercise effects
Active ingredients usually exert their effects by interacting with a molecular target structure, called a drug target. Drug targets include receptors, enzymes, transporters, and ion channels. A prerequisite for this is binding of the active ingredient to the target structure. Paul Ehrlich’s saying “Corpora non agunt nisi fixata” (Bodies do not act unless they are bound) and Emil Fischer’s lock-and-key principle are famous in this context.
Examples
Typical agents include:
- Acetylsalicylic acid (aspirin).
- Biologics
- Quinine
- Human insulin
- Imipramine (Tofranil)
- Morphine
- Paracetamol (Panadol)
- Penicillins
- Sildenafil (Viagra)
- Simvastatin (Zocor)
A large selection of active ingredients can be found here. This website lists all the major active ingredients.
