From Wikipedia, the free encyclopedia
An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicyclomine. Anticholinergics are administered to reduce the effects mediated by acetylcholine on acetylcholine receptors in neurons through competitive inhibition. Therefore, their effects are reversible.
[edit] Pharmacology
Anticholinergics are classified according to the receptors that are affected:
Examples of anticholinergics • ipratropium bromide (Atrovent) • oxitropium bromide (Oxivent) • tiotropium (Spiriva)
Physostigmine is one of a few drugs that are used as antidotes for anticholinergic poisoning. Nicotine also counteracts antichlolinergics.
[edit] Effects
Anticholinergic drugs are used in treating a variety of conditions:
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 experienced recreational drug users, possibly due to the lack of euphoria caused by them. (For some of the recreational effects, see the article on 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.
Possible effects of anticholinergics include:
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 [1]
- Inability to concentrate
- Wandering thoughts; inability to sustain a train of thought
- Incoherent speech
- 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"
- Visual, auditory, or other sensory hallucinations[1]
- Warping or waving of surfaces and edges
- Textured surfaces
- "Dancing" lines; "spiders", insects; form constants
- Lifelike objects indistinguishable from reality
- Hallucinated presence of people not actually there
- Rarely: seizures, coma, and death
Acute anticholinergic syndrome is completely reversible and subsides once all of the toxin has been excreted. In ordinary circumstances, no specific treatment is indicated. However, in extreme cases, especially those that involve severe distortions of mental state, a reversible cholinergic agent such as physostigmine may be used.
[edit] Plant sources
The most common plants containing anticholinergic alkaloids are:
[edit] Use as a deterrent
Certain preparations of some drugs, such as Hydrocodone, are mixed with an anticholinergic agent to deter intentional overdose. [2]
[edit] References
