Pharmacology (in Greek: pharmacon is drug, and logos is science) is the study of how chemical substances interfere with living systems. If these substances have medicinal properties, they are referred to as pharmaceuticals. The field encompasses drug composition, drug properties, interactions, toxicology, and desirable effects that can be used in therapy of diseases.

Development of medication is a vital concern to medicine, but also has strong economical and political implications. To protect the consumer and prevent abuse, many governments regulate the sale and administration of medication. In the United States, the main regulatory body is the Food and Drug Administration through its publication of the USP.

Pharmacology as a science is practiced by pharmacologists. A pharmacist is, in most countries, a university-schooled professional in pharmacy - drug dispensation and safety. Clinical pharmacology is the medical field of pharmacology; it mainly concerns poisoning and complex problems of medication.

Scientific background

The study of medicinal chemicals requires intimate knowledge of the biological system affected. With the knowledge of cell biology and biochemistry increasing, the field of pharmacology has also changed substantially. It has become possible, through molecular analysis of enzymes, to design chemicals that act on specific molecular pathways.

A chemical has, from the pharmacological point-of-view, various properties. Pharmacokinetics is its fate (e.g. its half-life and volume of distribution) in the organism, and pharmacodynamics is its mode of action and potential toxicity.

When describing the pharmacokinetic properties of a chemical, a pharmacologist employs the ADME principle:

• Absorption - How is the medication absorbed (through the skin, the intestine, the oral mucosa)?
• Distribution - How does it spread through the organism?
• Metabolism - Is the medication converted chemically, and into which substances. Are these active? Could they be toxic?
• Excretion - How is the medication eliminated (through the bile, urine, skin)?

Medication is said to have a narrow or wide therapeutic margin or therapeutic window. Those with a narrow window are more difficult to dose and administer, and may require therapeutic drug monitoring (examples are warfarin, some antiepileptics, aminoglycoside antibiotics).

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.

Types of medication

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 (Anaesthetic drugs)

analgesics (includes acetaminophen, NSAIDs and opioids), local anesthetics, general anaesthetics, sedatives, migraine treatment drug

For musculo-skeletal disorders

NSAIDs, muscle relaxant, neuromuscular drug
anticholinesterase, COX-2 inhibitor

For the eye

antibiotic, topical antibiotic, astringent, NSAIDs, miotics, adrenergic neurone blocker, carbonic anhydrase inhibitor, ocular lubricant, mydriatic

For the ear, nose and oropharynx

sympathomimetic, antihistamine, anticholinergic, NSAIDs, steroid, antiseptic, local anesthetic, antifungal, cerumenolytic

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

contraceptive, oral contraceptives, spermicide, depot contraceptives

For obstetrics and gynaecology

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

For infections and infestations

antibiotic, antifungal, antileprotic, antituberculous drug, antimalarial, anthelmintic, amoebicide, antiviral, antiprotozoal, antiserum

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.

External links

• International Conference on Harmonisation (http://www.ich.org/)
• US Pharmocopea (http://www.usp.org)