Cholinergic-Blocking Drugs
AKA anticholinergics, parasympatholytics, and antimuscarinic drugs
-drugs that block or inhibit the actions of ACh in the PNS
MOA of cholinergic-blocking drugs
- competitive antagonists
- compete with ACh for binding at muscarinic receptors in the PNS
- When these drugs bind to receptors, they inhibit nerve transmission at these receptors
Cholinergic-Blocking drug effects on cardiovascular
increased in large doses
cholinergic-blocking drug effects on CNS
small doses-excitation
Lg doses- drowsy, diorientation
cholinergic-blocking drug effects on Eye
mydriasis
decreased accomodation
Cholinergic-blocking drug effects on GI
decreased secretions, motility, peristalsis, relaxed smooth muscle tone
Cholinergic-blocking drug effects on GU
relaxed detrusor muscle
increased constriction of internal sphincter
Cholinergic-blocking drug Respiratory
decreased bronchial secretions
dilated bronchial airways
Indications for cardiovascular
- affects the hearts conduction system
- low doses: slow HR
- high doses: block inhibitory vagal effects on SA and AV node pacemaker cells
Indications for Respiratory
-Blocking the cholinergic stimulation of the PSNS allows unopposed action of the SNS
Indications for respiratory
-the PNS controls gastric secretions and smooth muscles that produce gastric motility
Toxicity and Overdose
- symptomatic and supportive therapy
- Continuous electrocardigraphic monitoring
- activated charcoal
- Treatment of shock
- Physostigmine
Atropine
- naturally occurring antimuscarininc
- uses: brady, ventricular asystole, antidote for anticholinesterase inhibitor taxicity or poisoning, and preoperatively to reduce salivation and GI secretions
- contraindications: angle-closure glaucoma, advanced hepatic and renal dysfunction, hiatal hernia associated with reflux esophagitis, intestinal atony, obstructive GI or GU condtions, and severe ulcerative colitis
Dicyclomine (Bentyl)
- synthetic antispasmodic cholinergic blocker
- uses: functional distrubances of GI motility such as IBS
- contraindications: known hypersensitivity to anticholinergics, angle-closure glaucoma, GI tract obstruction, myashtenia gravis, paralytic ileus, GI atony, and toxic megacolon
Glycopyrrolate (Robinul)
- synthetic antimuscarinic drug
- blocks receptor sites in the autonomic nervous system that control the production of secretions
- use: preoperatively to reduce salivation and excessive secretions in the repiratory and GI tract
- can also be given IV as antidote to cholinergic meds
Oxybutynin (Ditropan)
- synthetic antimuscarinic drug
- PO transdermal patch, topical gel
- uses: overactive bladder and antispasmodic for neuogenic bladder associated with spinal cord injuries and congenital conditions such as spina bifida
- DRY MOUTH
Scopolamine
- naturally occuring cholinergic blocker and one of the principal belladonna alkaloids
- uses: prevention of motion sickness and to help prevent postop, postanesthesia N/V
- contraindications: angle-closure glaucoma, advanced hepatic and renal dysfunction, hiatal hernia associated with reflux exophagitis, intestinal atony, obstructive GI or GU conditions, and severe ulcerative colitis
- AE: drowsiness, dry mouth, and blurred vision
- Using scopolamine with CNS depressants or alcohol may increase sedation
Tolerodine (Detrol)
- muscarinic receptor blocker
- PO-ER capsule
- uses: urinary frequency, urgency, and urge incontinence caused by bladder overactivity
- newer drugs are associated with a much lower incidence of dry mouth, partly because of their pharmacologic specificity for the bladder as opposed to the salivary glands
Mirabegron (Myrbetriq)
- Newer agent used to treat overactive bladder
- Beta3 agonist; represents a new class of therapy for this condition- NOT AN ANTICHOLINERGIC
- does not have same side effects as other drugs to treat overactive bladder
SAFETY ALERT
BEERS
anticholinergic drugs are potentially inappropriate for use in geriatric patients
What is the antidote for atropine overdose?
Physostigmine
