Medicines

Medicines are substances intended to diagnose, treat, cure, or prevent disease, or to relieve symptoms. They can be derived from natural sources, synthesized chemically, or produced using living systems (biologics). Medicines exert therapeutic effects by interacting with biological targets such as receptors, enzymes, or cellular pathways, thereby altering physiological processes.

They are categorized into prescription medicines, which require a clinician’s authorization, and over-the-counter medicines, which are available without a prescription in many jurisdictions. Other categories include vaccines, biologics (such as monoclonal antibodies), gene therapies, and traditional or herbal medicines. Medicines may be used alone or in combination with other therapies.

Development and regulation: Most medicines undergo discovery and preclinical testing in laboratory and animal studies, followed by phased clinical trials in humans (Phase I-III) to assess safety and efficacy. If successful, regulators review the data and may grant marketing authorization. Post-marketing surveillance monitors safety after widespread use.

Use and administration: Dosing depends on age, weight, organ function, and condition. Forms include tablets, capsules, liquids, injections, inhalers, topical creams, and implants. Pharmacokinetics describes how the body absorbs, distributes, metabolizes, and excretes a drug; pharmacodynamics describes its biological effects. Proper labeling and patient education are important for safe use.

Safety and risk: Medicines can cause adverse effects or interact with other medicines, foods, or diseases. Contraindications identify situations where use is unsafe. Storage and disposal guidelines protect potency and safety. Pharmacovigilance collects reports of adverse events to improve safety.