Pharmacology

Pharmacology (in Greek: pharmacon (φάρμακον) is drug, and logos (λόγος) is science) is the study of how chemical substances interact 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 manufacture, 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. Studies can include theoretical pharmacology, in contrast to Clinical pharmacology, - the medical field of 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 enzymes, to design chemicals that act on specific metabolic pathways by affecting sites directly on cell-surface receptors (which modulate and mediate nerve cell pathway signals, thus the pathways themselves).

A chemical has, from the pharmacological point-of-view, various properties. Pharmacokinetics is its rate (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.

Pharamcology comes with side-disciplines too: Neuropsychopharmacology, a mix between psychology, biochemistry, and neurobiology. Clinical pharmacology does not worry about research, but what is already known about trade-name drugs and their interactions with human receptors/pathways. This is the ultimate shelf science for pharmacists. The real meat comes in pharmacological research.

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)

This is a tricky class of drugs to classify due to mass misinformation on their nature. Aspirin is only a painkiller as far as the presence of certain inflammation-causing enzymes (including the Cyclooxygenases) goes: aspirin only serves to inhibit this enzyme's action. It does not alter perception of pain at all, thus does not address pain, thus is not a pain killer. Most doctors think it is and forego the fact that the acid-properties of aspirin can directly cause ulcers, acid-reflux, and probably other ailments.

The non-steroidal anti inflammatory drugs are in the same boat, but they are more dangerous than aspirin because they're synthetic, and the full effect of them on the entirety of the human biochemistry system has not even begun to be explored holistically (the same with antidepressants---like walking on ice before knowing what "ice" is). These little devils are propionic acid (three carbon carboxylic acid) derivatives and inhibit a slightly different, more selective pathway of inflammatory-causing enzymes. Drugs like celecoxib (celebrex) and Vioxx are the MOST dangerous...avoid these at all costs. Morphine is a hundred times safer, and won't give you cancer.

Now, aspirin generally treats inflammation, and NSAID's selectively treat it. Both are good for headaches due to their minor (or indirect) vasodilator effects, especially in combination with the best pain drug ever isolated/quote unquote invented, morphine. This is safest drug on the planet, and the best for treating pain. It should always be first-order, unless a patient is allergic to it. Nature has been experimenting with morphine since the angiosperm papaver somniferum has been around. Early humans in neolithic switzerland used poppies for either pain relief, or religious rituals, much like shaman, since the dried casings of poppy pods were found littering settlement sites in recent archeological reports. Man has been developing biochemically alongside the poppy since agriculture has been born, so we tolerate it extremely well, in general.

Pharmacology: It stimulates the mu-opioid receptors present in several evolutionarily OLDER parts of the brain, especially the nucleus accumbens, amygdala, and the mesolimbic systems. There are three types of opioid receptors: mu, kappa, and delta. Mu is responsible for euphoria-associated pain relief.

Increasing a steady dose of morphine leads to receptor upregulation. Normally endorphins and enkephalins (peptidic (protein) painkillers already present in our systems) mediate pain relief, but when the pain is sustained, it lasts long after those protein molecules have been broken down, so we need morphine (some of us). Endorphins and enkephalins handle the pain without affecting receptor populations. Morphine causes receptors to STICK to the surface of nerve cells, and not renew themselves, so the nerve cells make more receptors. The morphine eventually dissociates, then you're left with too many receptors for the endorphins and enkephalins to handle, they must fill a bigger glass so to speak. Increasing doses of morphine will lead to so many receptors that once you run out of morphine, endorphins and enkephalins won't have a chance of filling even 10% of the receptors needed for pain relief, so withdrawl then occurs, which is a fancy way of saying the body flushes the receptors out, back to a reasonable population density. Physiologically this means hell for the abuser, and he or she could easily die from how weak the immune system becomes from this process.

Oxycontin (oxycodone), vicodin (hydrocodone), and hydromorphone (dilaudid), oxymorphone (?), darvocet (propoxyphene), ultram (tramadol), and many others are all synthetic analogues of the original phenanthrene morphine ring structure, and thus have not been tested nearly as long as morphine has apropos the human system (thousand of years), and should generally be avoided. That especially goes for heroin, originally a cure for morphine addiction!!

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

contrast media

For euthanasia

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

External links

• International Conference on Harmonisation
• US Pharmocopea
• Davabazaar.co.in

See also

• Cosmeceuticals
• Drug design
• List of withdrawn drugs
• Medicare Part D - the new prescription drug plan in the U.S.
• Medicinal chemistry
• Pharmaceutical company
• Psychopharmacology - medication for mental conditions