Anticholinergic

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An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. Anticholinergics inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, etc. Anticholinergics are divided into three categories in accordance with their specific targets in the central and/or peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.[1]

Medical and recreational uses[edit]

Anticholinergic drugs are used in treating a variety of conditions:

Anticholinergics generally have antisialagogue effects (decreasing saliva production), and most produce some level of sedation, both being advantageous in surgical procedures.[2]

When a significant amount of an anticholinergic is taken into the body, a toxic reaction known as acute anticholinergic syndrome may result. This may happen accidentally or intentionally as a consequence of recreational drug use. Anticholinergic drugs are usually considered the least enjoyable by many recreational drug users,[3] possibly due to the lack of euphoria caused by them. In terms of recreational use, these drugs are commonly referred to as deliriants. Because most users do not enjoy the experience, they do not use it again, or do so very rarely. The risk of addiction is low in the anticholinergic class. The effects are usually more pronounced in the elderly, due to natural reduction of acetylcholine production associated with age.

Exceptions to the above include scopolamine, orphenadrine, dicycloverine/dicyclomine and first-generation antihistamines with central nervous system penetration.

Side effects[edit]

Possible effects of anticholinergics include:

Possible effects in the central nervous system resemble those associated with delirium, and may include:

A common mnemonic for the main features of anticholinergic syndrome is the following:

Remedies[edit]

Acute anticholinergic syndrome is completely reversible and subsides once all of the causative agent has been excreted. Reversible cholinergic agents such as physostigmine can be used in life-threatening cases. Wider use is discouraged due to the significant side effects, such as rapid heart beat and decreased blood pressure.

Piracetam (and other racetams), α-GPC and choline are known to activate the cholinergic system and alleviate cognitive symptoms caused by extended use of anticholinergic drugs.[citation needed]

Pharmacology[edit]

Anticholinergics are classified according to the receptors that are affected:

Examples[edit]

Examples of common anticholinergics:

Plants of the Solanaceae family contain various anticholinergic tropane alkaloids, such as scopolamine, atropine, and hyoscyamine.

Physostigmine is one of only a few drugs that can be used as an antidote for anticholinergic poisoning. Nicotine also counteracts anticholinergics by activating nicotinic acetylcholine receptors. Caffeine (although an adenosine receptor antagonist) is able to counteract the anticholinergic symptoms by reducing sedation and increasing acetylcholine activity, thereby causing alertness and arousal.

Plant sources[edit]

The most common plants containing anticholinergic alkaloids are:

Use as a deterrent[edit]

Certain preparations of some drugs, such as hydrocodone, are mixed with an anticholinergic agent to deter intentional overdose.[7]

References[edit]

  1. ^ Urinary Incontinence. Landon Center on Aging .
    Instructor: Sharee A. Wiggins, NP, Post-MS(N), ARNP, BC-GNP, BC-ANP.
    Module Revised by: Sharee A. Wiggins, NP and Tomas Griebling, MD
  2. ^ Page 592 in: Cahalan, Michael D.; Barash, Paul G.; Cullen, Bruce F.; Stoelting, Robert K. (2009). Clinical Anesthesia. Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-8763-7.  [1]
  3. ^ a b Bersani, F. S.; Corazza, O.; Simonato, P.; Mylokosta, A.; Levari, E.; Lovaste, R.; Schifano, F. (2013). "Drops of madness? Recreational misuse of tropicamide collyrium; early warning alerts from Russia and Italy". General Hospital Psychiatry 35 (5): 571–3. doi:10.1016/j.genhosppsych.2013.04.013. PMID 23706777.  edit
  4. ^ Talan, Jamie (July–August 2008). "Common Drugs May Cause Cognitive Problems". Neurology Now 4 (4): 10–11. doi:10.1097/01.NNN.0000333835.93556.d1. Retrieved 2008-08-17. 
  5. ^ Orthostatic hypotention & anticholinergics
  6. ^ Shytle, RD; Penny, E; Silver, AA; Goldman, J; Sanberg, PR (Jul 2002). "Mecamylamine (Inversine): an old antihypertensive with new research directions". Journal of Human Hypertension 16 (7): 453–7. doi:10.1038/sj.jhh.1001416. PMID 12080428. 
  7. ^ "NIH DailyMed - Hydromet Syrup". Retrieved 2008-08-17.