Chapter 21 Cholinergic-Blocking Drugs Flashcards
Cholinergic Blocking Drugs
Drugs that block the action of acetylcholine and substances similar to acetylcholine at receptor sites in the synapse
Mydriasis
dilation of the pupil of the eye, caused by contraction of the dilator muscle of the iris
Parasympatholytics
Drugs that reduce the activity of the parasympathetic nervous system; also called anticholinergics
True or False: the parasympathetic nervous system is the same as the sympathetic nervous system?
False, The parasympathetic nervous system is the branch of the autonomic nervous system with nerve functions opposite those of the sympathetic nervous system
What does a cholinergic receptor do?
A cholinergic receptor is one that binds acetylcholine and mediates its actions.
What are the different names for anticholinergics?
Cholinergic blockers, anticholinergics, parasympatholytics, and antimuscarinic drugs
What do parasympatholytics do?
They are a class of drugs that block or inhibit the actions of acetylcholine in the parasympathetic nervous system.
What do Cholinergic blocking drugs do?
Cholinergic blocking drugs block the action of the neurotransmitter acetylcholine at the muscarinic receptors in the PNS. Acetylcholine that is released from a stimulated nerve fiber is then unable to bind to the receptor site and fails to produce a cholinergic effect.
What does anticholinergics allow for?
Anticholinergics have many of the same effects as the adrenergics. Blocking the parasympathetic nerves allows the sympathetic (adrenergic) nervous system to dominate.
True or False: cholinergic blockers are competitive antagonists?
True, they compete with acetylcholine for binding at the muscarinic receptors of the PNS. Once they have bound to the receptor, they inhibit cholinergic nerve transmission. This occurs at the neuroeffector junction, or the point where the nerve ending reaches the effector organ such as smooth muscle, cardiac muscle, and glands.
True or False: Cholinergic blockers have partial effects at low dosages?
False, cholinergic blockers have little effect at the nicotinic receptors, although at high doses they have partial blocking effects.
What are the major sites of action of the anticholinergics ?
The heart, respiratory tract, gastrointestinal tract, urinary bladder, eye, and exocrine glands.
True or False: Anticholinergic effects decrease heart rate
False, Anticholinergic effects on the cardiovascular system are seen as an increase in heart rate.
True of False: cholinergic blockers cause mydriasis?
Cholinergic blockers keep the sphincter muscle of the iris from contracting, which results in dilation of the pupil (mydriasis) and paralysis of the ocular lens (cycloplegia).
True of False: Anticholinergics are indicated for Parkinson’s?
True
What are the cholinergic blocking effects of the Cardiovascular system?
Small doses= decrease heart rate
Large doses= increase heart rate
What are the cholinergic blocking effects of the central nervous system?
Small doses: decrease muscle rigidity and tremors. Large doses: causes drowsiness, disorientation, hallucinations.
What are the cholinergic blocking effects of the eye?
Dilate pupils (mydriasis), decrease accommodation by paralyzing ciliary muscles (cycloplegia)
What are the cholinergic blocking effects of the gastrointestinal body system?
Relaxed smooth muscle tone of gastrointestinal tract, decrease intestinal and gastric secretions, decrease motility and peristalsis.
What are the cholinergic blocking effects of genitourinary body system?
Relax detrusor muscle of bladder, increase constriction of internal sphincter, these two effects may result in urinary retention.
What are the cholinergic blocking effects of glandular body system?
decrease bronchial secretions, salivation, and sweating.
What are the cholinergic blocking effects of the respiratory system?
Decrease bronchial secretions, dilate bronchial airways.
What are some contraindications to the use of anticholinergic drugs?
Drug allergy angle closure glaucoma acute asthma respiratory distress myasthenia graves acute cardiovascular instability GI or GU tract obstruction
What are Cholinergic blockers adverse effects for the cardiovascular body system?
Increased heart rate
dysrhymias
tachycardia,
palpitations
What are Cholinergic blockers adverse effects for the eye?
dilated pupils (causing blurred vision) increased intraocular pressure
What are Cholinergic blockers adverse effects for the central nervous system?
Excitation, restlessness, irritability, disorientation, hallucinations, delirium, ataxia, drowsiness, sedation, confusion
What are Cholinergic blockers adverse effects for the gastrointestinal system?
decreased salivation
gastric secretions
motility (causing constipation)
What are Cholinergic blockers adverse effects for the genitourinary system?
Urinary retention
What are Cholinergic blockers adverse effects for the glandular system?
Decreased sweating
What are Cholinergic blockers adverse effects for the respiratory system?
Decreased bronchial secretions
What is the treatment for cholinergic blocker overdose?
symptomatic and supportive therapy.
The patient should be hospitalized with continuous electrocardiographic monitoring. Activated charcoal is effective in removing from the GI tract and any drug that has yet to been absorbed.
What are drug interactions most commonly reported with additive anticholinergic effects?
Amantadine, antihistamines, antidepressants, and digoxin
True or False: Atropine is naturally occurring antimuscarinic?
True
What is atropine contraindicated in?
Atropine is contraindicated in patients with angle-closure glaucoma, and it should be used with caution in patients with advanced hepatic and renal dysfunction, hiatal hernia associated with reflux esophagitis, intestinal atony, obstructive GI or GU conditions, and severe ulcerative colitis.
What is Atropine used for?
Treat increased heart rate, bradycardia, and ventricular asystole, and cardiopulmonary resuscitation.
it is more potent than scopolamine in its cholinergic-blocking effects on the heart and in its effects on the smooth muscles of the bronchi and intestines
antidote for anti-cholinesterase inhibitor toxicity or poisoning.
What is Dicyclomine (Bentyle) used for?
Dicyclomine is a synthetic antispasmodic cholinergic blocker used primarily in the treatment of functional disturbances of GI motility such as irritable bowl syndrome.
What is the contraindicated for dicyclomine?
hypersensitivity to anticholinergics angle-closure glaucome GI tract obstruction myasthenia graves paralytic ileus GI atony, toxic megacolon
What is Glycopyrrolate used for?
Glycopyrrolate (robinul) is used as a synthetic antimuscarinic drug that blocks receptor sites in the autonomic nervous system that control the production of secretions.
it is used preoperatively to reduce salivation and excessive secretions I the respiratory and GI tracts.
What is Glycopyrrolate contraindicated with?
patients who are hypersensitive to it angle-closure glaucoma, myasthenia graves, GI or GU tract obstruction, tachycardia, myocardial ischemia, hepatic disease, ulcerative colitis, toxic megacolon
What is Oxybutynin (Ditropan) used for?
Oxybutynin is a synthetic antimuscarinic drug used for the treatment of overactive bladder (OAB).
It is also used as an antispasmodic for neurogenic bladder assoaciated with spinal cord injuries and congenital conditions such as spina bifida.
What are the contraindications for oxybutynin?
Drug allergy
urinary or gastric retention
uncontrolled angle closure glaucoma
What is scopolamine used for?
prevention of motion sickness.
What is tolterodine used for?
Tolterodine is a muscarinic receptor blocker used for the treatment of urinary frequency, urgency, and urge incontience caused by bladder (detrusor) overactivity.
Tolterodine should be avoided with patients who have?
angle-closure glaucome,
urinary retention
