Chapter 18
Beta receptors cause:
Dilation
Adrenergic Drugs Mechanism of Action: Mixed-acting sympathomimetic
Directly stimulates the receptor by binding to it. Indirectly stimulates the receptor by causing the release of stored neurotransmitters from vesicles in the nerve endings.
Ophthalmic
Drugs that are used in the eye.
Adrenergic agonist drugs
Drugs that stimulate and mimic the sympathetic nervous system. Also known as adrenergic agonists or sympathomimetics.
Sympathomimetic
Drugs used therapeutically that mimics the catecholamines epinephrine, norepinephrine, and dopamine. Also called adrenergic agonists.
Sympathetic Nervous System
Fight or Flight
Adverse Effects: Alpha-adrenergic
Headache, restlessness, excitement, insomnia, euphoria Chest pain, vasoconstriction, reflexive bradycardia, palpitations, dysrhythmias Anorexia, dry mouth, nausea, vomiting, taste changes
Nasal congestion:
Intranasal (topical) application causes constriction of dilated arterioles and reduction of nasal blood flow, thus decreasing congestion. Alpha-1 adrenergic receptors Examples: Ephedrine, naphazoline, oxymetazoline, phenylephrine, and tetrahydrozoline
Alpha-1
Located on postsynaptic effector cells (the cell, muscle, or organ that the nerve stimulates)
Alpha-2
Located on presynaptic nerve terminals (the nerve that stimulates the effector cells) Controls the release of neurotransmitter
Adverse Effects: Beta-adrenergic
Mild tremors, headache, nervousness, dizziness Increased heart rate, palpitations, fluctuations of blood pressure Sweating, nausea, vomiting, muscle cramps
Cardiovascular:
Used to support the heart during cardiac failure or shock. Examples: Dobutamine, Ephedrine, Fenoldopam, Midodrine, Dopamine, Epinephrine, Norepinephrine, Phenylephrine
Drug Interactions
o Adrenergic antagonists o Anesthetic drugs o MAOIs o Antihistamines o Thyroid preparations
The autonomic nervous system contains:
sympathetic and parasympathetic nervous system
Catecholamines
Substances that can produce a sympathomimetic response. They are either endogenous catecholamines (such as epinephrine, norepinephrine, and dopamine) or synthetic catecholamine drugs (such as dobutamine).
Ophthalmic:
Temporary relief of conjunctival congestion (eyes) Alpha-adrenergic receptors Examples: epinephrine, naphazoline, phenylephrine, tetrahydrozoline Reduction of intraocular pressure and dilation of pupils: treatment of open-angle glaucoma Alpha-adrenergic receptors Examples: epinephrine and dipivefrin
Synaptic cleft
The space either between two adjacent nerve cell membranes or between a nerve cell membrane, and an effector organ cell membrane (also called synapse).
Neurotransmitter Catecholamines:
-Norepinephrine -Epinephrine -Dopamine
Dopaminergic Receptors cause dilation of:
-Renal -Mesenteric -Coronary -Cerebral
When a patient has lung disease, how much fluid should we encourage each day?
3000 mL
Autonomic Nervous System
A branch of the peripheral nervous system that controls autonomic bodily functions. It consists of the sympathetic nervous system and the parasympathetic nervous system.
Alpha-adrenergic receptors
A class of adrenergic receptors that are further subdivided into alpha-1 and alpha-2 adrenergic receptors.
Dopaminergic receptor
A third type of adrenergic receptor (in addition to alpha-adrenergic and beta-adrenergic receptors) located in various tissues and organs and activated by the binding of the neurotransmitter dopamine, which can be either endogenous or a synthetic drug form.
Positive dromotropic effect
An increase in the conduction of cardiac electrical impulses through the atrioventricular node, which results in the transfer of nerve action potentials from the atria to the ventricles. This ultimately leads to a systolic heartbeat (ventricular contractions).
Positive chronotropic effect
An increase in heart rate.
Adrenergic Drugs Mechanism of Action: Direct-acting sympathomimetic
Binds directly to the receptor and causes a physiologic response.
Autonomic functions
Bodily functions that are involuntary and result from the physiologic activity of the autonomic nervous system. The functions often occur in pairs of opposing actions between the sympathetic and parasympathetic divisions of the autonomic nervous system.
Respiratory:
Bronchodilators: drugs that stimulate beta-2 adrenergic receptors of bronchial smooth muscles causing relaxation, resulting in bronchodilation Examples: Albuterol, ephedrine, epinephrine, formoterol, levalbuterol, metaproterenol, pirbuterol, and salmeterol
Adrenergic Drugs Mechanism of Action: Indirect-acting sympathomimetic
Causes release of catecholamine from storage sites (vesicles) in nerve endings. Catecholamine then binds to receptors and causes a physiologic response.
Alpha receptors cause:
Constriction
Parasympathetic Nervous System
Rest and Digest
Mydriasis
Pupillary dilation, whether natural (physiologic) or drug induced.
Adrenergic receptors
Receptor sites for the sympathetic neurotransmitter's norepinephrine and epinephrine.
Beta-Adrenergic receptors
Receptors located on postsynaptic cells that are stimulated by specific autonomic nerve fibers. Beta-1 adrenergic receptors are located primarily in the heart, whereas beta-2 adrenergic receptors are located in the smooth muscle fibers of the bronchioles, arterioles, and visceral organs.
Overactive Bladder:
Relaxes the detrusor muscle during the storage phase of the bladder fill cycle. Increases bladder storage capacity Example: Mirabegron (Meretrix)
