Pharmacology
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Pharmacology (in Greek: pharmacon (φάρμακον) meaning drug, and logos (λόγος) meaning science) is the study of how chemical substances interact with living systems. If substances have medicinal properties, they are considered pharmaceuticals. The field encompasses drug composition and properties, interactions, toxicology, therapy, and medical applications and antipathogenic capabilities. The science is considered to have been invented by Arabic physicians in Baghdad during the Golden Age of Islam; pharmacopoeias were penned in Arabic as early as the 7th century (Amin A. Khairallah: Outline of Arabic Contributions to Medicine: Chapter X, Chemistry and Pharmacy. 1946, ).
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 manufacture, sale, and administration of medication. In the United States, the main body that regulates pharmaceuticals is the Food and Drug Administration and they enforce standards set by the United States Pharmacopoeia.
Pharmacology as a science is practiced by pharmacologists. Subdisciplines are clinical pharmacology (the medical field of medication effects on humans), neuro- and psychopharmacology (effects of medication on behavior and nervous system functioning), and theoretical pharmacology.
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 receptors, to design chemicals that act on specific cellular signalling or metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate cellular signalling pathways controlling cellular function).
A chemical has, from the pharmacological point-of-view, various properties. Pharmacokinetics describes its behaviour in the body - particularly in the blood (e.g. its half-life and volume of distribution), and pharmacodynamics relates its behaviour in the blood to its effects (desired effects or toxic side-effects).
When describing the pharmacokinetic properties of a chemical, pharmacologists are often interested in ADME:
- 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 inside the body, and into which substances. Are these active? Could they be toxic?
- Excretion - How is the medication eliminated (through the bile, urine, breath, skin)?
Medication is said to have a narrow or wide therapeutic index or therapeutic window. This describes the ratio of desired effect to toxic effect. A compound with a narrow therapeutic index (close to 1) exerts its desired effect at a dose close to its toxic dose. A compound with a wide therapeutic index (greater than 5) exerts its desired effect at a dose substantially below its toxic dose. 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). Most anti-cancer drugs have a narrow therapeutic margin: toxic side-effects are almost always encountered at doses used to kill tumours.
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 (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, 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, corticosteroid
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
For euthanasia
A euthanaticum is used for euthanasia and physician-assisted suicide, see also barbiturates.
Other
Zoopharmacognosy: Animal usage of drugs and non-foods.
External links
See also
- Cosmeceuticals
- Drug design
- List of withdrawn drugs
- Medicare Part D - the new prescription drug plan in the U.S.
- Medicinal chemistry
- Neuropsychopharmacology - The detailed comprehensive study of mind, brain and drugs.
- Neuropharmacology - The Molecular and Behavior study of Disease and Drugs in the Nervous System
- Pharmaceutical company
- Pharmacotherapy
- Pharmakos
- Psychopharmacology - medication for mental conditions
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