More Adrenergic Drugs

Adrenergic Drugs
Chapter 17 Outline

I Adrenergic Drugs
A. Drugs with effects that are similar to or mimic the effects of the SNS neurotransmitters NE, EPI, and dopamine.
B. Catecholamine: produces a sympathomimetic response.
1. endogenous
a. NE: stimulate Alpha
b. Epi: stimulates Beta
c. dopamine: dopaminergic receptors
2. synthetic
a. dobutamine
b. phenylephrine
c. isoproterenol
C. When these drugs are given they bathe the area between the nerve and the effector cell (synaptic cleft) and induces a response. (agonist b/c they bind to receptors and cause a response)
1. direct: binds to a receptor and causes a physiologic response. Drug itself binds to receptor.
a. EPI
b. NE
2. indirect: causes release of catecholamines from the storage sites (vesicles) in the nerve endings. Drug releases endongenous catech.
a. amphetamine
3. combination: directly stimulates the receptor by binding to it and indirectly stimulates the receptor by causing the release of the neurotrans stored in the vesicles at the nerve endings
a. ephedrine
II Noncatecholamine adrenergic drugs: structurally dissimilar to the endogenous catecholamines and generally have a longer duration of action than either the endogenous or synthetic catecholamines.
A. Phenylephrine
B. metaproterenol
C. albuterol
III Mechanism of Action and Drug Effects
A. When the drugs stimulate Alpha 1 smooth muscle, vasoconstriction occurs
1. blood vessels: vasoconstriction
2. CNS stimulation (speed, amphetamine)
2. GI smooth muscles: relaxation
3. Uterus and bladder: contraction
4. male ejaculation
5. decreased insulin release
6. contraction of the ciliary muscles resulting in dilation, mydriasis
B. Beta 1: myocardium & conduction of heart
1. increased force of contraction (Positive Inotropic Effect)
2. increase in heart rate (positive chronotropic effect)
3. increase in nerve impulses AVnode (positive dromotropic effect)
C. Beta 2:
1. relaxation of the bronchi (bronchodilation)
2. relaxation of the uterus
3. increased glycogenolysis in the liver
4. increase in renin secretion in the kidneys
IV Indications
A. Respiratory
1. bronchodilators: B2 (may also affect uterine and vascular smooth muscles)
a. asthma
b. bronchitis
c. albuterol, bitolterol, ephedrine, epinephrine, formoterol, salmeterol,
B. Topical Nasal Decongestants
1. A1: constriction of dilated arterioles & reduction in nasal blood flow decreasing congestion
a. epi, ephedrine, naphazoline, phenylephrine, tetrahydrozoline
C. Opthalmic
1. A1
2. temporarily relieve conjunctival congestion by causing arteriolar vasoconstriction.
a. epinephrine, phenylephrine, naphazoline, tetrahydrozoline (Visine)
3. reduce intraocular pressure and dilate the pupils (mydriasis) helpful in glaucoma. Stimulate A1 or B2 or both.
a. epinephrine
b. dipivefrin
D. Cardiovascular
1. AKA: cardioselective/vasoactive sympathomimetics, vasoconstrictive drugs, vasopressive, pressors, inotropes
2. Used to support the heart during cardiac failure or shock.
3. Variety of effects on various Alpha and Beta receptors which are related to the specific dose of the drug.
4. dobutamine (a, b), dopamine (a, b, dopa), epinephrine (a + b), norepinephrine (a + b)
5. In practice we use what works best. Can run meds together.
a. epi: increase heart rate
b. ne: constrict blood vessels (raise bp, lower pulse)
c. dopamine: from chart
d. dobutamine: heart beat stronger
V About the Receptors: (see chart for organs affected)
A. Alpha
1. located on presynaptic nerve terminals
2. control the release of neurotransmitters
3. alpha-adrenergic agonist responses
a. vasoconstriction
b. CNS stimulation (speed)
B. Beta
1. located on postsynaptic effector cells (organ itself)
2. Beta 1 = heart
3. Beta 2 = lungs (smooth muscle of the bronchioles, arterioles, and visceral organs)
C. Dopaminergic receptors
1. an additional adrenergic receptor
2. stimulated by dopamine
3. Causes dilation resulting in increased blood flow of:
a. renal
b. mesenteric
c. coronary
d. cerebral

VI Contradictions
A. Only known allergy and severe hypertension

VII Adverse Effects (many are the same for alpha and beta)
A. Alpha
1. CNS effects
a. headache
b. restlessness
c. excitement
d. insomnia
e. euphoria
2. cardiovascular
a. chest pain
b. vasoconstriction
c. hypertension
d. tachycardia
e. palpitations
f. dysrhythmias
3. other systems
a. anorexia
b. dry mouth
c. nausea
d. vomiting
e. taste changes (rarely)
B. Beta
1. CNS
a. mild tremors
b. headache
c. nervousness
d. dizziness
2. cardiovascular
a. increased heart rate
b. palpitations (dysrhythmias)
c. fluctuations in BP
3. other systems
a. sweating
b. nausea
c. vomiting
d. muscle cramps

VIII Interactions
A. Anesthetic agents
B. tricyclic antidepressants
C. MAOI’s
D. Antihistamines
E. thyroid preparations
F. antihypertensives
G. Will directly antagonize another adrenergic agent, resulting in reduced effects. We never usually use 2 at once.

Nursing Implications

I Assess
A. for allergies
B. history of HPN
C. cardiac dysrhythmias
D. other cardiovascular disease
E. renal, hepatic, and cardiac function before treatment.
II Perform baseline assessment of vital signs, peripheral pulses, skin color, temperature, and capillary refill. Include postural bp and pulse
III follow administration guidelines
IV IV administration
A. check iv site often for infiltration
B. use clear iv solutions
C. use an infusion device/IV pump
D. infuse agent slowly/properly to avoid dangerous CV effects
E. monitor cardiac rhythm
V In chronic lung disease
A. instruct pts to avoid factors that exacerbate their condition
B. encourage fluid intake (up to 3000ml/day if permitted)
C. educate about proper dosing, use of equipment (MDI, spacer, nebulizer) and equipment care.




Etc:
Salmeterol is indicated for prevention of bronchospasms, not management of acute symptoms.

Overuse of nasal decongestants may cause rebound nasal congestion or ulcerations.

Avoid OTC or other medications b/c of possible interactions.

Administering 2 adrenergic agents together may precipitate severe cardiovascular effects such as tachycardia or HPN.

Inform pts taking inhaled isoproterenol that their sputum may turn pink.

Monitor for therapeutic effects:
A. cardiovascular:
1. decreased edema
2. increased urinary output
3. return to normal vital signs
4. improved skin color and temp
5. increase LOC
B. asthma
1. return to normal respiratory rate
2. improved breath sounds, fewer rales
3. increased air exchange
4. decreased cough
5. less dyspnea
6. improved blood gasses
7. increased activity tolerance

If the heart is damaged or in failure give vasoactive sympathomimetics (pressors) b/c it makes the heart beat harder/faster. Helps support heart during cardiac failure or shock. (When in shock blood vessels dilate)

This chapter made simple:
NE: constricts blood vessels
Epi: increases heart rate...used in shock
Dopa: increases blood flow to kidneys
Dobutamine: heart to beat strong/fast

Questions
Which of the following are naturally occurring and can also be synthesized? (NE, epi, dopamine)

Which of the following causes an increased force of contraction? (inotropic, chromotropic, dromotropic)

Can we give epi pen for an asthma attack?
Constricts blood vessels
Increases heart rate
Increases conduct
Dilates lungs
Yes, b/c asthma constricts the lungs, epi dilates. The problem is the side effect of raising the heart rate.

Can we use albuterol for a b sting? (no effect on alpha 1)

Will epi cause beta 2 effects?

When we think of adrenergic basic concept we are talking about 3 receptors: Alpha, beta, dopa.


When we speak of adernergic/ sympathomimetic system we know A1 is our primary receptor that causes vaso constriction overall. B1, heart. B2, lungs.

Dopa receptors are: kidney, coronary, cerebral, messentary and they have the opposite effect where dilation INCREASES blood flow.

Primary drugs are NE, EPI, and albuterol

NE and epi affect both alpha1, and both betas. Dopa affects only dopaminergic receptors.