Pharm-cardiac-catecholamines Flashcards
what are the physiological actions of sympathomiometic amines (7 things)?
- peripheral excitation-
- peripheral inhibitory action-
- cardiac excitation
- endocrine effects
- metabolic effects
- cns effects
- pre synaptic effects
what is periphreal excitation?
vasoconstriction of smooth muscles in blood vessels perfusing skin
what is peripheral inhibitory action?
relax smooth muscle in gut, broncioles, and blood vessels prerfusing skeletal muscles
what are sub types of adrenergic receptors & where are they found?
alpha 1- found in blood vessels, urinary sphincter
alpha 2- found in CNS & pre-synaptically
beta 1- found in heart
beta 2- found in lungs, pancreas, vessels, bladder, uterus, GI tract
what are the sympathomimetic amines actions on the heart?
chronotropic
dromotropic
inotropic
what are the 2 metabolic (energy) effects of sympathomimetic amines?
enhanced glycogenolysis and lipolysis
what are endocrine actions of sympathomimetic amines?
can modulate the secretion of insulin
action of sympathomimetic amines in the cns
released by neurons in the brain where they influence LOC and inhibit appetite
sympathomimetics on presynaptic terminals (what receptors, & what does their activation cause)?
alpha 2 receptors are pre synaptic on adrenergic terminals (activation inhibits the release of norepi).
- name an alpha 1 prototypical agonist?
2. prototypical antagonist?
- agonist=phenylephrine
2. antagonist=prazosin
- alpha 2 prototypical agonist?
2. antagonist?
- A2 agonist=clonidine
2. A2 antagonist=yohimbine
- beta one prototypical agonist?
2. antagonist?
- agonist: dobutamine
2. antagonist: metoprolol
beta two protatypical agonist?
terbutaline
dose .25 mg SQ
- epinephrine: the catecholamine ___?
- what receptors does it activate?
- what does it cause (BP)
- what is a side effect of this?
- the catecholamine PROTOTYPE (the big gun)
- activates both alpha and beta receptors
- causes increase in blood pressure
- there is some rebound hypotension before normalizing d/t initial stimulation of beta receptors (which cause vasodilation).
- what are effects of epi on heart? what does it increase overall? what receptors?
- blood vessels? what increases overall? what receptors?
- inotrope, dromotrope, & chronotrope; increases cardiac output; B1.
- vasoconstriction of blood vessels servicing the skin; increases total periphreal resistance»TPR which increases BP; A1.
- what is the depressor effect?
2. why are there pressor and depressor effects?
- the depressor effect is vasodilation of blood vessels that supply skeletal muscles caused by epi (shunt blood to muscles during fght or flight)
- because you are shifting blood flow from organs of minor relevance (by “pressor”) vasoconstriction in an emergency to muscles by vasodilation (or “de-presor”) to facilitate survival (fight or flight)
what will any drug that infulences BP cause?
some sort of compensatory reflex and or baroreceptor response (as long as reflex is intact).
—–decrease pressure on baroreceptors, heart rate decreases; increase pressure baroreceptors, heart rate increases—-
drugs that influence cardiac functions can also cause what?
cardic arrhythias (ex. high doses of epi cause arrhythmias) this is a negative effect
what does epi do to these organs? what receptors for each?
- bladder (receptors) & sphincters (receptors)
- uterus (in 3rd trimester) (receptors)
- with that being said, what could you use epi for in pregnancy?
- what is this receptor action?
- bladder: relaxation of detrussor muscle of bladder (Beta 2); contraction of sphinctors (Alpha 1)- causing urinary retention
- uterus: variable response depening on phase of cycle, gestation etc. –during last trimester or so: inhibits tone and contractions (beta 2)
- epi can be used to prevent premature labor
- this is a Beta 2 agonist action because beta 2 activation relaxes the uterus.
epi effect on: (& what receptor is affected/ stimulated)?
- gi tract
- bronchiole smooth muscle
- the GI tract is relaxed by epi; peristalsis is slowed, tone reduced (gi motility not importain in fight or flight)-Beta 2 effect
- bronchioles relaxed by epi - Beta 2 effect
epi effect on metabolism:
1. effect on glycogen; what receptor; what does it cause?
2. effect on fat; what receptor; what does it cause?
3. effect on insulin; receptor; why?
4,. in a “nut shell”, epinephrine does what (as far as metabolism) for what?
- enhances glycogenolysis (??Alpha 1 or Beta 2??): results in increased glucose (energy source for fight of flight)
- increases lipolysis (Beta 3), allowing for more free fatty acids (for quick energy)
- insulin secretion inhibited by epi (Alpha 2 effect), prevents insulin from transporting glucose into cells right away.
- breaks glycogen into glucose and breaks fat into fatty acids; inhibits insulin all to increase available energy sources for immediate use.
- how effective is PO epi?
- how about SQ
- Inhaled?
- GI absorption is negligable (insignificant)
- SQ action is slowed d/t vasoconstricting properties (which makes it a good additive to LAs)
- inhalation effects are restricted to respiratory system, but it can cause arrhythmias (more selective drugs are better)
epi effects:
- what affect does 1-2 mcg/min have (on what receptors)?
- what does 4 mcg/min effect and what receptors?
- 1-2 mcg/min stimulate Beta 2 receptors in periphery; vasodilation of skeleta muscle vessels causes modest drop in BP
- 4 mcg/min stimulats Beta 1 receptors; this causes :
- increased HR
- increased CO (d/t increased HR, contractility & venous return)
- increased systolic BP (d/t increased rate & c.o.)
what does 10-20 mcg/min of epi stimulate?
- alpha and beta (alpha more)
- alpha 1: cutaneous, mucosal, hepatorenal vasoconstriction
- beta 2: vasodilation and increased rennin secretion
epi dose for cardiac arrest:
- beginning?
- intermediate?
- escalating doses?
- high?
- ETT dose?
- beginning:1 mg IV q 3-5 min
- intermediate: 2-5 mg q 3-5 min
- escalating: 1mg, then 3mg, then 5 mg q 3 minutes
- high does: 0.1 mg/kg iv q 3-5 min
- ETT: 2-2.5 higher than IV dose and diluted with 10cc NS or distilled water
epinephrine for bronchodilator:
- IM or SQ dose
- onset
- nebulized dose
- onset
- epi (1:1,000) 0.1-0.5 mg IM or SQ q 15 min to 4 hrs
- onset: 5-10 min
- nebulized: 8-15 gtt: give 1 to 3 treatments q 4-6 hours
- onset: less than 1 minute
hypersensitivity epi dose;
- IM?
- IV (if hypotension)?
- folowed by Infusion of what rate?
- 0.3-0.5 mg IM or SQ; repeat PRN
- hypotension: 0.1 mg iv slow push over 5-10 min
- followed by gtt of 1-10 mcg/min