Chapter 15: Adrenergic Agonists and Antagonists Flashcards
2 Drug groups that affect Sympathetic Nervous System
Adrenergic Agonists/Sympathomimetics and Adrenergic Antagonists/Sympatholytics
It is an involuntary system of the PNS
Autonomic Nervous System
Neurotransmitters of Sympathetic NS
Norepinephrine and Epinephrine
Enzymes that inactivate these neurotransmitters
MAO and COMT
Alpha 1 receptor sites
Blood vessels, eyes, bladder and prostate
What happens when a1 receptor in blood vessels is stimulated?
Vasoconstriction > Increased peripheral resistance > Increased BP
What happens when a1 receptor in eyes is stimulated?
Mydriasis (Pupil Dilation)
What happens when a1 receptor in bladder is stimulated?
Relaxation (holds urine)
What happens when a1 receptor in prostate is stimulated?
Contraction
Alpha 2 receptor sites
Smooth muscles of GI and Blood vessels
What happens when a2 receptor in blood vessels is stimulated?
Vasodilation > Decreased BP (reduced norepinephrine)
What happens when a2 receptor in GI is stimulated?
Decrease in GI tone and motility
Beta 1 receptor sites
Heart and Kidney
What happens when b1 receptor in heart is stimulated?
Increased heart contraction > Increased heart rate
What happens when b1 receptor in kidney is stimulated?
Increased renin secretion > Increased angiotensin > Increased BP
Beta 2 receptor sites
Smooth muscles of GI, smooth muscles of lungs, liver and uterus
What happens when b2 receptor in GI is stimulated?
Decreased GI tone and motility
What happens when b2 receptor in lungs is stimulated?
Bronchodilation
What happens when b2 receptor in uterus is stimulated?
Uterine relaxation
What happens when b2 receptor in liver is stimulated?
Activation of glycogenolysis > Increased blood glucose
Classification of sympathomimetics that stimulates release of norepinephrine in nerve terminal ending and its example drug
Indirect-acting sympathomimetic (Amphetamine)
Classification of sympathomimetics that stimulates release of norepinephrine in nerve terminal ending and stimulate adrenergic receptor sites and its example drugs
Mixed-acting sympathomimetics (Ephedrine, Pseudoephedrine)
Pseudoephedrine
Mixed-acting
Increases heart rate
Relieves nasal and sinus congestion
Contraindicated in hypertension, closed-angle glaucoma, bronchitis, emphysema and urinary retention
Use w/ caution in DM
Albuterol Sulfate
B2 adrenergic agonist
Bronchodilation (prevents bronchospasm)
Side effects of Albuterol
Tremors
Headache
Tachycardia
Palpitation
Dysrhythmia
Nausea and vomiting, dizziness
Urinary retention
Nervousness
Epinephrine (Drug class and Drug & Lab interaction)
DRUG CLASS: Sympathomimetic adrenergic agonist
DRUG INTERACTION:
Dysrhythmia may occur when taken with Digoxin
LAB: Increased blood glucose and serum lactic acid
What are the contraindications of Epinephrine?
Parkinsonism
Closed-angle glaucoma
Hypertension
Hyperthyroidism
Cerebrovascular, cadiac and renal diseases
Labor, pregnancy and breastfeeding
Renal dysfunction
Hypovolemia
Diabetes Mellitus
What are the therapeutic effects of Epinephrine?
Nasal congestion
Allergic reaction
Anaphylaxis
Asthma exacerbation, status asthmaticus
Bronchospasm
Angioedema
Cardiac arrest and resuscitation
Mechanism of Action of Epinephrine
Acts on alpha and beta receptors
Promotes bronchodilation
Reverse anaphylactic reactions
Reduces mucosal congestion by inhibiting histamine release
Increased cardiac rate and output
Side effects of Epinephrine
Nausea, vomiting and dizziness
Tremor, paresthesia and weakness
Hypo/hyperglycemia
Oliguria
Pallor
Adverse Effects of Epinephrine
Palpitations
Tachycardia
Hypertension
Dyspnea (SOB)
Renal insufficiency
Injection site reaction
LT: Dysrhythmia, pulmonary edema
How is epinephrine excreted?
Breastmilk and urine
Why can’t epinephrine be administered orally?
rapidly metabolized in GI and liver > unstable serum levels
How is epinephrine administered?
IM, IV and endotracheal
What happens when epinephrine and digoxin are administered together?
Cardiac dysrhythmia
Clonidine
Selective a2 adrenergic agonist
Used primarily for hypertension
Effects of Clonidine
Bradycardia
Hypotension
Sedation
Dry mouth (very low doses)
An alpha adrenergic agonist that acts within the CNS, causes activation of A2 receptors (vasodilation > decreased BP)
It is not usually used anymore due to several side effects
Methyldopa
Adverse effects of central-acting alpha-adrenergic agonists (Clonidine & Methyldopa)
Headache, nightmares and drowsiness
Nasal congestion
Constipation
Edema
Ejaculation dysfunction
Elevated hepatic enzymes
What is Perfusion?
Passage of blood flow through capillaries and arteries, which delivers oxygen and nutrients to body cells
Drugs that block the effects of adrenergic neurotransmitter
Adrenergic antagonists
Adrenergic blocker
Sympatholytic
Drugs that block or inhibit a response at the alpha-adrenergic site
Alpha-adrenergic antagonists
Alpha blockers
Selective alpha blockers
Block Alpha 1
Nonselective alpha blockers
Blocks Alpha 1 and 2
Drugs that inhibit a response at beta-adrenergic site
Beta-adrenergic antagonist
Beta blockers
Alpha antagonists promotes vasodilation….
Decreased BP > Orthostatic Hypertension
Propranolol Hydrochloride
First beta blocker for treatment of angina, cardiac dysrhythmia, hypertension and heart failure
Drug Interaction of Atenolol
- Increased absorption with atropine and other anticholinergics
- Decreased effects with NSAIDs
- Increased risk of hypoglycemia with insulin and sulfonylureas
- Increased hypotension with prazosin and terazosin
- Increased lidocaine and verapamil levels with toxicity
What beta blocker is prescribed for decreasing pulse rate and bp
Atenolol or Metoprolol
Atenolol drug class and ROA
Beta1-adrenergic blocker
PO and IV
Atenolol Contraindications
Hypersensitivity
Bradycardia
Heart block greater that first degree
Cardiogenic shock
Uncompensated cardiac failure
Caution:
RENAL DYSFUNCTION
DM
BRONCHOSPASM
MYASTHENIA GRAVIS
PULMONARY EDEMA
ACUTE BRONCHOSPASM
PREGNANCY
LACTATION
TRUE OR FALSE: Beta blockers should be suddenly discontinued.
FALSE. Should be gradually discontinued in smaller dosages.
How is Atenolol excreted?
Urination
Half life of Atenolol
6-7 hours
