Anticholinergic


Anticholinergic
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. Pharmacology
Anticholinergics are classified according to the receptors that are affected:
Antimuscarinic agents operate on the muscarinic acetylcholine receptors. The majority of anticholinergic drugs are
antimuscarinics. Antinicotinic agents operate on the nicotinic
acetylcholine receptors. The majority of these are non-depolarising
skeletal muscle relaxants for surgical use that are structurally related to curare. Several are depolarizing agents. Examples
Examples of common anticholinergics: Anti-Muscarinic agents Atropine
Benztropine (Cogentin) Biperiden
Chlorpheniramine (Chlor-Trimeton) Dicyclomine (Dicycloverine)
Dimenhydrinate (Dramamine) Diphenhydramine (Benadryl, Sominex, Advil
PM, etc.) Doxylamine (Unisom)
Glycopyrrolate (Robinul) Ipratropium (Atrovent)
Orphenadrine Oxitropium (Oxivent)
Oxybutynin (Ditropan, Driptane, Lyrinel XL) Tolterodine (Detrol, Detrusitol)
Tiotropium (Spiriva) Trihexyphenidyl
Scopolamine Solifenacin
Tropicamide Atropine
Benztropine (Cogentin) Biperiden
Chlorpheniramine (Chlor-Trimeton) Dicyclomine (Dicycloverine)
Dimenhydrinate (Dramamine) Diphenhydramine (Benadryl, Sominex, Advil
PM, etc.) Doxylamine (Unisom)
Glycopyrrolate (Robinul) Ipratropium (Atrovent)
Orphenadrine Oxitropium (Oxivent)
Oxybutynin (Ditropan, Driptane, Lyrinel XL) Tolterodine (Detrol, Detrusitol)
Tiotropium (Spiriva) Trihexyphenidyl
Scopolamine Solifenacin
Tropicamide Anti-Nicotinic agents Bupropion (Zyban, Wellbutrin) – Ganglion blocker
Dextromethorphan – Cough suppressant and ganglion blocker
Doxacurium – Nondeplorizing skeletal muscular relaxant
Hexamethonium – Ganglion blocker Mecamylamine – Ganglion blocker and occasional
smoking cessation aid Tubocurarine – Nondepolarizing skeletal muscular
relaxant Bupropion (Zyban, Wellbutrin) – Ganglion blocker
Dextromethorphan – Cough suppressant and ganglion blocker
Doxacurium – Nondeplorizing skeletal muscular relaxant
Hexamethonium – Ganglion blocker Mecamylamine – Ganglion blocker and occasional
smoking cessation aid Tubocurarine – Nondepolarizing skeletal muscular
relaxant 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)
would counteract the anticholinergic symptoms by reducing sedation and increase acetylcholine
activity, thereby causing alertness and arousal. Medical and recreational uses
Anticholinergic drugs are used in treating a variety of conditions:
Gastrointestinal disorders (e.g., gastritis, diarrhea, pylorospasm, diverticulitis, ulcerative
colitis, nausea, and vomiting) Genitourinary disorders (e.g., cystitis, urethritis,
and prostatitis) Respiratory disorders (e.g., asthma, chronic
bronchitis, and chronic obstructive pulmonary disease )
Sinus bradycardia due to a hypersensitive vagus nerve. Insomnia, although usually only on a short
term basis. Dizziness (including vertigo and motion sickness-related
symptoms) Anticholinergics generally have antisialagogue
effects (decreasing saliva production), and most have at least some sedative effect, both
being advantageous in surgical procedures. 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, 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. Acute Anticholinergic Syndrome
Possible effects of anticholinergics include: Ataxia; loss of coordination
Decreased mucus production in the nose and throat; consequent dry, sore throat
Xerostomia or dry-mouth with possible acceleration of dental caries
Cessation of perspiration; consequent decreased epidermal thermal dissipation leading to warm,
blotchy, or red skin Increased body temperature
Pupil dilation (mydriasis); consequent sensitivity to bright light (photophobia)
Loss of accommodation (loss of focusing ability, blurred vision – cycloplegia)
Double-vision (diplopia) Increased heart rate (tachycardia)
Tendency to be easily startled Urinary retention
Diminished bowel movement, sometimes ileus (decreases motility via the vagus nerve)
Increased intraocular pressure; dangerous for people with narrow-angle glaucoma
Shaking Possible effects in the central nervous system
resemble those associated with delirium, and may include:
Confusion Disorientation
Agitation Euphoria or dysphoria
Respiratory depression Memory problems
Inability to concentrate Wandering thoughts; inability to sustain a
train of thought Incoherent speech
Irritability Mental confusion (brain fog)
Wakeful myoclonic jerking Unusual sensitivity to sudden sounds
Illogical thinking Photophobia
Visual disturbances Periodic flashes of light
Periodic changes in visual field Visual snow
Restricted or “tunnel vision” Periodic flashes of light
Periodic changes in visual field Visual snow
Restricted or “tunnel vision” Visual, auditory, or other sensory hallucinations Warping or waving of surfaces and edges
Textured surfaces “Dancing” lines; “spiders”, insects; form
constants Lifelike objects indistinguishable from reality
Phantom smoking Hallucinated presence of people not actually
there Warping or waving of surfaces and edges
Textured surfaces “Dancing” lines; “spiders”, insects; form
constants Lifelike objects indistinguishable from reality
Phantom smoking Hallucinated presence of people not actually
there Rarely: seizures, coma, and death
Orthostatic hypotension (sudden dropping of systolic blood pressure when standing up suddenly)
and significantly increased risk of falls in the elderly population. A common mnemonic for the main features of
anticholinergic syndrome is the following: Hot as a hare (hyperthermia)
Blind as a bat (dilated pupils) Dry as a bone (dry skin)
Red as a beet (vasodilation) Mad as a hatter (hallucinations/agitation)
The bowel and bladder lose their tone and the heart goes on alone (ileus, urinary retention,
tachycardia) Remedies
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. Plant sources
The most common plants containing anticholinergic alkaloids are:
Atropa belladonna (Deadly Nightshade), source of atropine
Brugmansia species (Brugmansia) Datura species (Datura)
Hyoscyamus niger (Henbane) Mandragora officinarum (Mandrake)
Use as a deterrent Certain preparations of some drugs, such as
hydrocodone, are mixed with an anticholinergic agent to deter intentional overdose.

3 comments

  1. down likers of this video are real blind people. It is mentioned here that video is targeted for blind who can't see Wikipedia pages and hence an audio version of the same

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