Medication

Overview
A medication, medicine or drug is any substance or combination of substances administered to human beings or animals to treat or prevent disease; alternatively to assist in medical diagnosis. Commercial medications are produced by pharmaceutical companies and are often patented. Copies of former patented drugs are called generic drugs.

Classification
Medication can be usually classified in various ways, e.g. by its chemical properties, mode of administration, or biological system affected. An elaborate and widely used classification system is the Anatomical Therapeutic Chemical Classification System(ATC system).

For the gastrointestinal tract or digestive system

 * Upper digestive tract: antacids, reflux suppressants, antiflatulents, antidopaminergics, proton pump inhibitors, H2-receptor antagonists, cytoprotectants, prostaglandin analogues
 * Lower digestive tract: laxatives, antispasmodics, antidiarrhoeals, bile acid sequestrants, opioids

For the cardiovascular system

 * General: beta-receptor blocker, calcium channel blockers, diuretics, cardiac glycosides, antiarrhythmics, nitrate, antianginals, vasoconstrictor, vasodilator, peripheral activator
 * Affecting Blood pressure: ACE inhibitors, angiotensin receptor blockers, alpha blocker
 * Coagulation: anticoagulant, heparin, antiplatelet drug, fibrinolytic, anti-hemophilic factor, haemostatic drugs
 * Atherosclerosis/cholesterol agents: hypolipidaemic agents, statins.

For the central nervous system
hypnotic, anaesthetics, antipsychotic, antidepressant (including tricyclic antidepressants, monoamine oxidase inhibitor, lithium salt, selective serotonin reuptake inhibitor), anti-emetic, anticonvulsant and antiepileptic, anxiolytic, barbiturate, movement disorder drug, stimulant (including amphetamines), benzodiazepine, cyclopyrrolone, dopamine antagonist, antihistamine, cholinergic, anticholinergic, emetic, cannabinoids, 5-HT antagonist

For pain & consciousness (analgesic drugs)
The main classes of painkillers are NSAIDs, opioids and various orphans such as paracetamol, tricyclic antidepressants and anticonvulsants.

For musculo-skeletal disorders
NSAIDs (including COX-2 selective inhibitors), muscle relaxant, neuromuscular drug anticholinesterase

For the eye

 * General: adrenergic neurone blocker, astringent, ocular lubricant
 * Diagnostic: topical anesthetics, sympathomimetics, parasympatholytics, mydriatics, cycloplegics
 * Anti-bacterial: antibiotics, topical antibiotics, sulfa drugs, aminoglycosides, fluoroquinolones
 * Anti-viral:
 * Anti-fungal: imidazoles, polyenes
 * Anti-inflammatory: NSAIDs, corticosteroids
 * Anti-allergy: mast cell inhibitors
 * Anti-glaucoma: adrenergic agonists, beta-blockers, carbonic anhydrase inhibitors/hyperosmotics, cholinergics, miotics, parasympathomimetics, prostaglandin agonists/prostaglandin inhibitors.  nitroglycerin

For the ear, nose and oropharynx
sympathomimetic, antihistamine, anticholinergic, NSAIDs, steroid, antiseptic, local anesthetic, antifungal, cerumenolyti

For the respiratory system
bronchodilator, NSAIDs, anti-allergic, antitussive, mucolytic, decongestant corticosteroid, beta-receptor antagonist, anticholinergic, steroid

For endocrine problems
androgen, antiandrogen, gonadotropin, corticosteroid, growth hormone, insulin, antidiabetic (sulfonylurea, biguanide/metformin, thiazolidinedione, insulin), thyroid hormones, antithyroid drugs, calcitonin, diphosponate, vasopressin analogues

For the reproductive system or urinary system
antifungal, alkalising agent, quinolones, antibiotic, cholinergic, anticholinergic, anticholinesterase, antispasmodic, 5-alpha reductase inhibitor, selective alpha-1 blocker, sildenafil

For contraception

 * Hormonal contraception
 * Ormeloxifene
 * Spermicide

For obstetrics and gynecology
NSAIDs, anticholinergic, haemostatic drug, antifibrinolytic, Hormone Replacement Therapy, bone regulator, beta-receptor agonist, follicle stimulating hormone, luteinising hormone, LHRH gamolenic acid, gonadotropin release inhibitor, progestogen, dopamine agonist, oestrogen, prostaglandin, gonadorelin, clomiphene, tamoxifen, Diethylstilbestrol

For the skin
emollient, anti-pruritic, antifungal, disinfectant, scabicide, pediculicide, tar products, vitamin A derivatives, vitamin D analogue, keratolytic, abrasive, systemic antibiotic, topical antibiotic, hormones, desloughing agent, exudate absorbent, fibrinolytic, proteolytic, sunscreen, antiperspirant, corticosteroid

For infections and infestations
antibiotic, antifungal, antileprotic, antituberculous drug, antimalarial, anthelmintic, amoebicide, antiviral, antiprotozoal

For immunology
vaccine, immunoglobulin, immunosuppressant, interferon, monoclonal antibody

For allergic disorders
anti-allergic, antihistamine, NSAIDs

For nutrition
tonic, iron preparation, electrolyte, parenteral nutritional supplement, vitamins, anti-obesity drug, anabolic drug, haematopoietic drug, food product drug

For neoplastic disorders
cytotoxic drug, sex hormones, aromatase inhibitor, somatostatin inhibitor, recombinant interleukins, G-CSF, erythropoietin

For diagnostics
contrast media

For euthanasia
A euthanaticum is used for euthanasia and physician-assisted suicide, see also barbiturates.

Euthanasia is not permitted by law in many countries, and consequently medicines will not be licenesed for this use in those countries.

Legal Considerations
Medications may be divided into over-the-counter drugs (OTC) which may be available without special restrictions, and prescription only medicine (POM), which must be prescribed by a licensed medical practitioner. The precise distinction between OTC and prescription depends on the legal jurisdiction.

The International Narcotics Control Board of the United Nations imposes a world law of prohibition of certain medications. They publish a lengthy list of chemicals and plants whose trade and consumption (where applicable) is forbidden. OTC medications are sold without restriction as they are considered safe enough that most people will not hurt themselves accidentally by taking it as instructed. Many countries, such as the United Kingdom have a third category of pharmacy medicines which can only be sold in registered pharmacies, by or under the supervision of a pharmacist.

Other/related topics
Polypharmacy: suggests that multiple use of prescribed and non-prescribed medications, (use of 5 or more), can have adverse effects on the recipient.

Zoopharmacognosy: Animal usage of drugs and non-foods.