Pharmaceutical drugs

A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.

Classification
Medications can be classified in various ways, such as by chemical properties, mode or route of administration, biological system affected, or therapeutic effects. An elaborate and widely used classification system is the Anatomical Therapeutic Chemical Classification System (ATC system). The World Health Organization keeps a list of essential medicines.

A sampling of classes of medicine includes:
 * 1) Antipyretics: reducing fever (pyrexia/pyresis)
 * 2) Analgesics: reducing pain (painkillers)
 * 3) Antimalarial drugs: treating malaria
 * 4) Antibiotics: inhibiting germ growth
 * 5) Antiseptics: prevention of germ growth near burns, cuts and wounds

For the gastrointestinal tract (digestive system)

 * Upper digestive tract: antacids, reflux suppressants, antiflatulents, antidopaminergics, proton pump inhibitors (PPIs), H2-receptor antagonistss, cytoprotectants, prostaglandin analogues
 * Lower digestive tract: laxatives, antispasmodics, antidiarrhoeals, bile acid sequestrants, opioid

For the cardiovascular system

 * General: &beta;-receptor blockers ("beta blockers"), calcium channel blockers, diuretics, cardiac glycosides, antiarrhythmics, nitrate, antianginals, vasoconstrictors, vasodilators, peripheral activators
 * Affecting blood pressure (antihypertensive drugs): ACE inhibitors, angiotensin receptor blockers, &alpha; blockers
 * Coagulation: anticoagulants, heparin, antiplatelet drugs, fibrinolytics, anti-hemophilic factors, haemostatic drugs
 * Atherosclerosis/cholesterol inhibitors: hypolipidaemic agents, statins.

For the central nervous system
Drugs affecting the central nervous system include: hypnotics, anaesthetics, antipsychotics, antidepressants (including tricyclic antidepressants, monoamine oxidase inhibitors, lithium salts, and selective serotonin reuptake inhibitors (SSRIs)), antiemetics, anticonvulsants/antiepileptics, anxiolytics, barbiturates, movement disorder (e.g., Parkinson's disease) drugs, stimulants (including amphetamines), benzodiazepines, cyclopyrrolones, dopamine antagonists, antihistamines, cholinergics, anticholinergics, emetics, cannabinoids, and 5-HT (serotonin) antagonists.

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
The main categories of drugs for musculoskeletal disorders are: NSAIDs (including COX-2 selective inhibitors), muscle relaxants, neuromuscular drugs, and anticholinesterases.

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
 * Antiviral drug:
 * 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
sympathomimetics, antihistamines, anticholinergics, NSAIDs, steroids, antiseptics, local anesthetics, antifungals, cerumenolyti

For the respiratory system
bronchodilators, NSAIDs, anti-allergics, antitussives, mucolytics, decongestants corticosteroids, beta-receptor antagonists, anticholinergics, steroids

For endocrine problems
androgens, antiandrogens, gonadotropin, corticosteroids, human growth hormone, insulin, antidiabetics (sulfonylureas, biguanides/metformin, thiazolidinediones, insulin), thyroid hormones, antithyroid drugs, calcitonin, diphosponate, vasopressin analogues

For the reproductive system or urinary system
antifungal, alkalising agents, quinolones, antibiotics, cholinergics, anticholinergics, anticholinesterases, antispasmodics, 5-alpha reductase inhibitor, selective alpha-1 blockers, sildenafils, fertility medications

For contraception

 * Hormonal contraception
 * Ormeloxifene
 * Spermicide

For obstetrics and gynecology
NSAIDs, anticholinergics, haemostatic drugs, antifibrinolytics, Hormone Replacement Therapy (HRT), bone regulators, beta-receptor agonists, follicle stimulating hormone, luteinising hormone, LHRH gamolenic acid, gonadotropin release inhibitor, progestogen, dopamine agonists, oestrogen, prostaglandins, gonadorelin, clomiphene, tamoxifen, Diethylstilbestrol

For the skin
emollients, anti-pruritics, antifungals, disinfectants, scabicides, pediculicides, tar products, vitamin A derivatives, vitamin D analogues, keratolytics, abrasives, systemic antibiotics, topical antibiotics, hormones, desloughing agents, exudate absorbents, fibrinolytics, proteolytics, sunscreens, antiperspirants, corticosteroids

For infections and infestations
antibiotics, antifungals, antileprotics, antituberculous drugs, antimalarials, anthelmintics, amoebicides, antivirals, antiprotozoals

For the immune system
vaccines, immunoglobulins, immunosuppressants, interferons, monoclonal antibodies

For allergic disorders
anti-allergics, antihistamines, NSAIDs

For nutrition
tonics, iron preparations, electrolytes, parenteral nutritional supplements, vitamins, anti-obesity drugs, anabolic drugs, haematopoietic drugs, [[food product drug]s

For neoplastic disorders
cytotoxic drugs, therapeutic antibodies, sex hormones, aromatase inhibitors, somatostatin inhibitors, recombinant interleukins, G-CSF, erythropoietin

For diagnostics
contrast media

For euthanasia
An euthanaticum is used for euthanasia and physician-assisted suicide.

Euthanasia is not permitted by law in many countries, and consequently medicines will not be licensed 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. A third category, behind-the-counter medications (BTMs), is implemented in some jurisdictions. BTMs do not require a prescription, but must be kept in the dispensary, not visible to the public, and only be sold by a pharmacist or pharmacy technician.

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.

For patented medications, countries may have certain mandatory licensing programs which compel, in certain situations, a medication's owner to contract with other agents to manufacture the drug. Such programs may deal with the contingency of a lack of medication in the event of a serious epidemic of disease, or may be part of efforts to ensure that disease treating drugs, such as AIDS drugs, are available to countries which cannot afford the drug owner's price.

In some countries, government-regulated cannabis is available by prescription.

Blockbuster drug
A blockbuster drug is a drug generating more than $1 billion of revenue for its owner each year. The search for blockbusters has been the foundation of the R&D strategy adopted by big pharmaceutical companies, but this looks set to change. New advances in genomics, and the promise of personalized medicine, are likely to fragment the pharmaceutical market.

A recent report from Urch Publishing estimated that about one third of the pharma market by value is accounted for by blockbusters. About 100 products are blockbusters. The top seller was Lipitor, a cholesterol-lowering medication marketed by Pfizer with sales of $12.2 billion.

Environmental impact
Since the 1990s water contamination by pharmaceuticals has been an environmental issue of concern. Most pharmaceuticals are deposited in the environment through human consumption and excretion, and are often filtered ineffectively by wastewater treatment plants which are not designed to manage them. Once in the water they can have diverse, subtle effects on organisms, although research is limited. Pharmaceuticals may also be deposited in the environment through improper disposal, runoff from sludge fertilizer and reclaimed wastewater irrigation, and leaky sewage. In 2009 an investigative report by Associated Press concluded that U.S. manufacturers had legally released 271 million pounds of drugs into the environment, 92% of which was the antiseptics phenol and hydrogen peroxide. It could not distinguish between drugs released by manufacturers as opposed to the pharmaceutical industry. It also found that an estimated 250 million pounds of pharmaceuticals and contaminated packaging were discarded by hospitals and long-term care facilities.

Ancient pharmacology
Using plants and plant substances to treat all kinds of diseases and medical conditions is believed to date back to prehistoric medicine.

The Kahun Gynaecological Papyrus, the oldest known medical text of any kind, dates to about 1800 BCE and represents the first documented use of any kind of medication. It and other medical papyri describe Ancient Egyptian medical practices, such as using honey to treat infections.

Ancient Babylonian medicine demonstrate the use of prescriptions in the first half of the 2nd millennium BC. Medicinal creams and pills were employed as treatments.

On the Indian subcontinent, the Atharvaveda, a sacred text of Hinduism whose core dates from sometime during the 2nd millenium BCE, although the hymns recorded in it are believed to be older, is the first Indic text dealing with medicine. It describes plant-based medications to counter diseases. . The earliest foundations of ayurveda were built on a synthesis of selected ancient herbal practices, together with a massive addition of theoretical conceptualizations, new nosologies and new therapies dating from about 400 BCE onwards. . The student of Āyurveda was expected to know ten arts that were indispensable in the preparation and application of his medicines: distillation, operative skills, cooking, horticulture, metallurgy, sugar manufacture, pharmacy, analysis and separation of minerals, compounding of metals, and preparation of alkalis.

The Hippocratic Oath for physicians, attributed to 5th century BCE Greece, refers to the existence of "deadly drugs", and ancient Greek physicians imported medications from Egypt and elsewhere.

The first drugstores were created in Baghdad in the 8th century CE. The injection syringe was invented by Ammar ibn Ali al-Mawsili in 9th century Iraq. Al-Kindi's 9th century CE book, De Gradibus, developed a mathematical scale to quantify the strength of drugs.

The Canon of Medicine by Ibn Sina (Avicenna), who is considered the father of modern medicine, reported 800 tested drugs at the time of its completion in 1025 CE. The Canon is considered the first pharmacopoeia, or organized list of medications and their preparation. Ibn Sina's contributions include the separation of medicine from pharmacology, which was important to the development of the pharmaceutical sciences. Islamic medicine knew of at least 2,000 medicinal and chemical substances.

Medieval pharmacology
Medieval medicine saw advances in surgery, but few truly effective drugs existed, beyond opium and quinine. Folklore cures and potentially poisonous metal-based compounds were popular treatments. Theodoric Borgognoni, (1205-1296), one of the most significant surgeons of the medieval period, responsible for introducing and promoting important surgical advances including basic antiseptic practice and the use of anaesthetics. Garcia de Orta described some herbal treatments that were used.

Modern pharmacology
For most of the nineteenth century, drugs were not highly effective, leading Oliver Wendell Holmes, Sr. to famously comment in 1842 that "if all medicines in the world were thrown into the sea, it would be all the better for mankind and all the worse for the fishes".

During the First World War, Alexis Carrel and Henry Dakin developed the Carrel-Dakin method of treating wounds with an irrigation, Dakin's solution, a germicide which helped prevent gangrene.

In the inter-war period, the first anti-bacterial agents such as the sulpha antibiotics were developed. The Second World War saw the introduction of widespread and effective antimicrobial therapy with the development and mass production of penicillin antibiotics, made possible by the pressures of the war and the collaboration of British scientists with the American pharmaceutical industry.

Medicines commonly used by the late 1920s included aspirin, codeine, and morphine for pain; digitalis, nitroglycerin, and quinine for heart disorders, and insulin for diabetes. Other drugs included antitoxins, a few biological vaccines, and a few synthetic drugs. In the 1930s antibiotics emerged: first sulfa drugs, then penicillin and other antibiotics. Drugs increasingly became "the center of medical practice". In the 1950s other drugs emerged including corticosteroids for inflammation, rauwolfia alkloids as tranqulizers and antihypertensives, antihistamines for nasal allergies, xanthines for asthma, and typical antipsychotics for psychosis. As of 2008, thousands of approved drugs have been developed. Increasingly, biotechnology is used to discover biopharmaceuticals.

In the 1950s new psychiatric drugs, notably the antipsychotic chlorpromazine, were designed in laboratories and slowly came into preferred use. Although often accepted as an advance in some ways, there was some opposition, due to serious adverse effects such as tardive dyskinesia. Patients often opposed psychiatry and refused or stopped taking the drugs when not subject to psychiatric control.

Governments have been heavily involved in the development and sale of drugs. In the U.S., the Elixir Sulfanilamide disaster led to the establishment of the Food and Drug Administration, and the 1938 Federal Food, Drug, and Cosmetic Act required manufacturers to file new drugs with the FDA. The 1951 Humphrey-Durham Amendment required certain drugs to be sold by prescription. In 1962 a subsequent amendment required new drugs to be tested for efficacy and safety in clinical trials.

Until the 1970s, drug prices were not a major concern for doctors and patients. As more drugs became prescribed for chronic illnesses, however, costs became burdensome, and by the 1970s nearly every U.S. state required or encouraged the substitution of generic drugs for higher-priced brand names. This also led to the 2006 U.S. law, Medicare Part D, which offers Medicare coverage for drugs.

As of 2008, the United States is the leader in medical research, including pharmaceutical development. U.S. drug prices are among the highest in the world, and drug innovation is correspondingly high. In 2000 U.S. based firms developed 29 of the 75 top-selling drugs; firms from the second-largest market, Japan, developed eight, and the United Kingdom contributed 10. France, which imposes price controls, developed three. Throughout the 1990s outcomes were similar.