Anticholinergics inhibits parasympathetics, by blocking the neurotransmitter acetylcholine [specifically, its binding to its receptor in neurons]. Parasympathetics are responsible for involuntary movement of smooth muscle present in the GI, urinary tract, lungs, etc.
What are anticholinergics?
It's drugs that inhibit the parasympathetics, which is the rest and digest response, by blocking acetylcholine. So rest and digest includes digestion, urination, and constriction of the breathing tubes.
GI disorders, including:
Genitourinary disorders, including:
Respiratory disorders, including:
Sinus bradycardia, due to a hypersensitive vagus nerve
Insomnia, although usually only on a short term basis
Dizziness, including vertigo, and motion sickness-related Sx
When do you want to give a drug to inhibit the rest and digest response?
If there's a GI problem, like diarrhea, diverticulitis, ulcerative colitis, vomiting. If there's a urinary problem, like inflammation of the bladder, urethra, or prostate. If there's a breathing problem, like asthma, or COPD.
Anticholinergics can be divided into their specific targets:
Antimuscarinics, which block activity of the muscarinic ACh receptor. These include:
Ipratropium [bromide] (Atrovent), which relieves bronchspasms. It is used to Tx COPD and acute asthma
Tiotropium [bromide](Spiriva), used to Mx COPD
Trihexyphenidyl +/- Benzhexol
[Post-]ganglionic blockers, by acting as a nicotinic antagonist
Neuromuscular blockers, which act presynaptically via inhibition of acetylcholine ACh, or postsnaptically at the ACh receptors of the motor nerve end-plate. This causes paralysis of the affected skeletal muscles
What are the different types of drugs that inhibit the rest and digest response?
The biggies are the antimuscarinics and antinicotinics. As it's mentioned, it acts against the muscarinic and nicotinic receptors. They're both receptors that bind acetylcholine.
Decreased mucus production in the nose and throat, causing dry, sore throat
Dry mouth w/ possible acceleration of dental caries
Pupil dilation, causing photophobia (sensitivity to bright light)
Tachycardia (increased HR)
Diminished bowel movement, sometimes ileus (decreased motility via the vagus nerve)
Ataxia (poor coordination)
Stopping of sweating, causing decreased epidermal thermal dissipation causing warm, blotchy, or red skin
Increased body temperature
Loss of accommodation, loss of focusing ability, blurred vision
Tendency to be easily startled
Increased IOP (intraocular pressure), dangerous for Pt's w/ narrow-angle glaucoma
What are the side effects of the drugs that inhibit the rest and digest response?
Because you're inhibiting the rest and digest response, you'd be worried about promoting things associated with the fight and flight response. So things like decreased mucus production, dry mouth, pupil dilation, increased heart rate, slower bowel movement, urinary retention.