Selective B2 Agonists Flashcards
B2 agonists
Selectively agonize B2
B2 receptors does what? Stimulate _______increase cAMP which in turn leads to _______(2)
Stimulated activity of adenylyl cyclase
Increase cAMP
1.Relaxation of bronchial smooth muscle/uterine smooth muscle
2. inhibitor of release of mediators of immediate hypersensitivity from cells (mast cells)
*****Selectivity is _____ at high doses and may______
****lost at high doses / High concentration of the agents and they can cause stimulation of B1 receptors at higher doses
One side effect of the heart seen with beta 2 agonists
Tachycardia.
Routes of administration
IV, SC, oral, INH
For bronchodilation effecs, which route is preferred? why?
Inhaled; it delivers the greatest concentration of drug to the lungs and minimizes systemic absorption
What should never be used to treat acute asthma?
LABA
Tocolytics means
To stop premature labor
NEVER USED here in US
ritodrine.
Ritodrine withdrawn in
1998
The only FDA approved Beta2 agonists to use as tocolytics______But currently ______Is used as tocolytics (off label )
Ritodrine: Terbutaline
3 Side effects of b2 adrenergic agonist
- Tremor- Beta 2 in skeletal muscles
- Tachycardia- Due to loss of B2 selectivity at high dosess
- Palpitations
In acute severe asthma, B2 agonists may cause _________how to fix ?
cause a decrease in arterial oxygenation presumed to reflect relaxation of compensatory vasoconstriction
- Give supplemental oxygenation
Beta 2 agonist will cause what in potassium
HYPOKALEMIA
What does beta 2 do to the sodium potassium pump?
drives K intracellular by stimulatin B2 receptors on the Na+ K+ ATPase pump
Drugs interactions
MAOis and TCAs (within 2 weeks of discontinuation)
CLASSIFICATION , how many classes
2 Short acting (SABA) and long acting (LABA)
Short acting B2-adrenergic agonist last?
Last for 6 hours
SABA , onset of action
fast onset of action
Albuterol has ________ and they are all
7 different names; short acting agents.
Albuterol sulfate
Racemix mixture : R and S (50-50)
R isomer of albuterol is the _______also called _______
active ; Levalbuterol
Levalbuterol is the
active ISOMER
Which is commercially available as MDI and solution for inhalation
R-enantiomer
Is levalbuterol better than albuterol? Why?
NO; same bronchodilator effects.
LABA duration of action is ______and is more ______ and _______than SABA
> 12 hours (more lipophilic, longer duration of action)
LABA- They all end in
- erol
Onset of action of LABA
<5minutes
***Should never be used to treat acute attack why?
****LABAs
Increases risk of asthma-related deaths with the use of long-term asthma control meds
Selective B3 adrenergic agonist
Myrbetriq
Myrbetriq FDA approved ____Agonists use to treat
Beta 3 ; Used to treat overactive bladder
Myrbetriq mechanism of action
Relaxes the detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle by activation of B3 receptors.
Most common adverse of myrbetriq
Hypertension
Midodrine is a (class)_______used to treat
Vasopressor/antihypotensive agent; orthostatic hypotension
Midodrine is a _______meaning it is inactive.
prodrug
Midodrine active metabolite activates
alpha 1 adrenergic receptors of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation in BP
For BOTH ________and _______Administering these medications in combination with ____,_____,_____ Increase risk of ______Hypertension when given with those agents? solution?
MIDODRINE AND DROXIDOPA,supine; NE, epinephrine and other vasopressors
Monitor BP closely
Northera (droxidopa)
Oral only agent that is used for NEUROGENIC ORTHOSTATIC HYPOTENSION
Synthetic amino acid precursor of norepinephrine
droxidopa
Beta 2 agents have
Sustained duration of action because of resistance to metabolism by COMT.
Is inhaled as effective as parenteral with SABA?
yes
SABA is the treatment of choice for ________and is also use as a prophylaxis agent to
Acute episode of bronchospasm
Prevent exercise-induced bronchospasm.
3 acute metabolic responses with B2
one rare adverse effect:
Hyperglycemia
Hypokalemia
Hypomagnesemia
Paradoxical bronchospasm.
***What are the only INHALED SABAs currently available
Albuterol
Levalbuterol
The effects of Albuterol and volatile anesthetics are bronchomotor tone are
Additive
Explain Droxidopa mechanism of action
directly metabolized into Epinephrine by the enzymes DOPA-Decarboxylas and norepinephrine then increases BP by inducing peripheral and venous vasoconstriction.
