ANS Pharmacology Flashcards
(38 cards)
Autonomic Nervous System
Main activities
•Three main activities
–Contraction of smooth muscle of the bronchi, blood vessels, gastrointestinal tract, eye, and genitourinary tract
–Contraction of cardiac muscle
–Secretion of salivary, sweat, and gastric glands
Structure and Function of the ANS
Two divisions
Organs and glands
•Two divisions –Sympathetic –Parasympathetic •Organs and glands –Receive nerves from both branches –Opposing actions
Fight-or-Flight Response (SNS)
What happens in the body?
Brain –Increased alertness and readiness •Cardiovascular –Increased heart rate and blood pressure •Musculoskeletal –Ready for sudden, intense physical activity •GI –Liver produces more glucose for energy; Decreased peristalsis •Respiratory –Dilation of bronchi, increased respirations •Pupils –Dilation, increased vision •Integumentary –Warm, increased perspiration •Genitourinary –Decreased urine formation
Rest-and-Digest (PNS)
What happens in the body?
•GI –Increased secretions –Increased peristalsis •Cardiovascular –Decreased heart rate and blood pressure •Respiratory –Constriction of bronchi, decrease respirations
What are the ANS Neurotransmitters?
- Norepinephrine (NE)
* Acetylcholine (Ach)
Classification of Autonomic Drugs
Stimulation of SNS –Sympathomimetics, adrenergic-agonists •Stimulation of PNS –Parsympathomimetics, muscarinic agonists •Inhibition of SNS –Adrenergic antagonists or blockers •Inhibition of PNS –Anticholinergics, parasympatholytics, muscarinic blockers
What are cholinergic receptors
- Can be activated directly or indirectly
- Found in the autonomic nervous system at the ganglia and the neuroeffector junctions
- Found in the somatic nervous system at the neuromuscular synapses
Direct Cholinergic Agonists
•Produce rest-and-digest responses
–Activate cholinergic synapses by releasing Ach into the synaptic cleft
–Drug binds to Ach receptors, enhancing action potential
–Drug inactivated by AchE
Indirect Cholinergic Agonists
•Drug binds AchE, preventing Ach from being destroyed
–Increases amount of Ach remaining in synaptic cleft
•Results in a greater effect
Effects of Muscarinic Agonists
- Increase degree of smooth muscle tone and contractions of the GI tract
- Stimulate smooth muscle of the urinary tract
- Stimulate most exocrine glands
- Cause contraction of the iris sphincter
- Contraction of bronchial smooth muscle
Precautions or muscarinic agonists
•Do not administer to patients with:
–Suspected obstructive disease of the gastrointestinal or genitourinary tract
–Asthma or COPD
•Monitor patients for reflex tachycardia
–Particularly hyperthyroid or cardiovascular patients
Indirect Acting
(Anticholinesterase Agents)
Side effects
•Common side effects
–Involuntary contraction or twitching of muscles, nausea/vomiting, miosis, increased salivation
•Serious adverse effects
–Bradycardia, hypotension, dyspnea, seizures, bronchospasm, cholinergic crisis, death due to paralysis of respiratory muscles
Potential Uses for AchE Inhibitors
- Alzheimer’s disease
- Glaucoma
- Protect against bioterrorist attack with nerve gases
- Myasthenia gravis
What are Muscarinic Antagonists?
And what are the reasons for their uses?
- Primarily block receptors in the parasympathetic nervous system
- May also be known as anticholinergics, cholinergic blockers, muscarinic antagonists, or parasympatholytics
- Work by competing with Ach for binding at muscarinic receptors, allowing sympathetic activation to dominate
•Are used for their parasympathetic actions –Dilation of the pupils –Increased heart rate –Drying of secretions –Bronchodilation
Uses of Muscarinic Antagonists
GI disorders such as IBS
•Ophthalmic procedures
•Cardiac rhythm disorders
•Adjuncts to anesthesia to decrease secretions
•Asthma for bronchodilation effects
•Antidotes for poisoning from muscarinic drugs
•Neurogenic bladder; Urge incontinence
•Parkinson’s disease
•Antidotes for poisoning from muscarinic drugs
•Urge incontinence
What are adrenergic receptors?
•Site where adrenergic drugs (neurotransmitters) bind and produce their effects
•Catecholamine’s (neurotransmitters) Act on receptor sites throughout the body – known as adrenergic receptors.
–Two major types of receptors-alpha and beta.
–Two subtypes for each :
● alpha 1 and alpha 2
●beta 1 and beta 2
Adrenergic receptors
How it acts on the alphas and beta
Act on: •Alpha 1- on postsynaptic effector cells –Tissue –Muscle –Organ •Alpha 2- on presynaptic nerve terminals (actually on the nerve) –Control release of neurotransmitters •Beta 1 – postsynaptic effector cells –Heart •Beta 2 – postsynaptic effector cells- smooth muscles of: –Bronchioles –Arterioles –Visceral organs (e.g. uterus)
Sympathomimetics
How to they work?
•Exert effects via two mechanisms
–Directly
●Binding to and activating adrenergic receptors
●Epinephrine, norepinephrine, dopamine
–Indirectly
●Increasing amount of norepinephrine available at adrenergic synapses
Adrenergic Agonists
What do they do?
•Activate sympathetic receptors in sympathetic nervous system
•Induce fight-or-flight response
•Two receptor types
–Alpha
–Beta
•Include norepinephrine, epinephrine, dopamine
Alpha1-Receptor Agonists
Why are they prescribed and what can they be used for?
- Generally prescribed for nasal congestion and hypotension
* May be used to produce mydriasis during ophthalmic exams
Beta1-Receptor Agonists
What are they for and what do they do?
•Critical care drugs –Heart attack –Heart failure –Shock •Have powerful affects on heart
Beta2-Receptor Agonists
What are they used for?
- Used to treat asthma
* Reduce preterm labor contractions of uterus
Vasoactive adrenergics
What are they used for/ what do they do?
What are some examples?
Used to support a failing heart or to treat shock
•Very potent, quick-acting, and their effects quickly cease when they are stopped
–epinephrine (Adrenaline), alpha & beta adrenergic, treat shock
–Dopamine- (Intropin) -beta1 adrenergic, IV only, to raise B/P,
–Norepinephrine- (Levophed) Alpha & Beta adrenergic
–dobutamine (Dobutrex)-beta 1 adrenergic, to treat cardiac decompression
Adrenergic drugs side/adverse effects
Alpha and beta
Alpha:
– headaches, restlessness, excitement, insomnia, euphoria
–Cardiovascular: chest pain, vasoconstriction, HTN, tachycardia, dysrhythmias
–Anorexia, dry mouth, N/V, taste changes
•Beta:
–Mild tremors, H/A, nervousness, dizziness
–Cardiovascular: increased heart rate, palpitations, dysrhythmias, B/P fluctuations
–Sweating, N/V, muscle cramps
