10 - Sympathomimetics Flashcards
Sympathomimetic agonists
direct acting
- alpha agonists
- –non selective
- –a1 selective
- –a2 selective
- beta agonists
- –non selective
- –b1 selective
- –b2 selective
indirect acting
- releasers
- reuptake inhibitors
MOA of sympathomimetics
direct activation of adrenoreceptors
indirect activation by increasing concentration of available catecholamines in the synapse
- release of stored catecholamines
- inhibition of reuptake
EPINEPHRINE class similar drug MOA uses SE
- sympathomimetic (non-selective, direct-acting)
- none
- activates a and b adrenergic receptors
a1 vasoconstriction, increases BP
b1 increased hr, conduction and contractility
b2 bronchodilation - cardiac arrest, anaphylaxis DOC, asthma, copd, hemostasis
- hypertension, tachycardia, ischemia, hyperglycemia
NORE class similar drug MOA uses SE
- sympathomimetic (non-selective, direct-acting)
- none
- activates a and b adrenergic receptors
a1 vasoconstriction, increases bp
b2 increased hr, conduction, and contractility
b2 bronchodilation - neurogenic shock, cardiogenic shock (last resort)
- extreme vasospasm, tissue necrosis, excessive blood pressure increase, arrythmias, infarction, reflex bradycardia
compensatory vagal reflexes tend to overcome the direct positive chronotropic effects; alpha>beta activity.
DOPAMINE class similar drug MOA uses SE
- sympathomimetic (non-selective, direct-acting)
- none
- activates a, b, and d1 adrenergic receptors
a1 vasoconstriction, increases bp
b1 increased hr, conduction, contractility
d1 vasodilation in splanchnic and renal vessels
Dose-dependent action of dopamine:
low dose
1-5 mcg/kg/min
- vasodilation int he splanchnic and renal vascular beds via D1 receptors
- increased renal blood flow and UO
Dose-dependent action of dopamine:
medium dose
5-15 mcg/kg/min
- increased renal blood flow, hr, cardiac contractility, and cardiac output via B1 receptors
Dose-dependent action of dopamine:
high dose
> 15 mcg/kg/min
- vasoconstriction and incrased blood pressure via a receptors
ISOPROTERENOL class similar drug MOA uses SE
- sympathomimetic (beta nonselective)
- none
- non selectively activates b adrenergic receptors
b1 increased hr, conduction, contractility
b2 bronchodilation - asthma
- cardiovascular disturbance, arrhythmias
PHENYLEPHRINE class similar drug MOA uses SE
- sympathomimetic (a1 selective agonist)
- pseudoephedrine, oxymetazoline, tetrahydrozoline, midodrine, naphazoline, xylometazoline
- selectively activates a1 adrenergic receptors
a1 vasoconstriction, increases BP - nasal decongestant, mydriatic, drug induced hypotension, orthostatic hypotension, spinal shock
- rebound nasal congestion, supine hypertension, stroke, MI, piloerection, urinary retention
ocular administration causes mydriasis without cyclopegia
CLONIDINE class similar drug MOA uses SE
- sympathomimetic a2 selective agonist
- none
- activates a2 adrenergic receptors
a2 decreases central sympathetic outflow - hypertension, cancer pain, opioid withdrawal
- sedation, rebound hypertension, dry mouth
taper use prior to discontinuation to avoid rebound hypertension
to treat rebound hypertension with clonidine, administer to treat rebound hypertension, administer ______
phentolamine
METHYLDOPA class similar drug MOA uses SE
- sympathomimetic a2 selective agonist
- guanfacine, guanabenz, dexmedetomidine, tizanidine
- activates a2 adrenergic receptors
a2 decreases central sympathetic outflow - pre-eclampsia, gestational hypertension, sedative (dexmedetomidine), muscle relaxant (tizanidine)
- sedation, hemolytic anemia (positive coomb’s test)
Coombs test
A Coombs test (also known as Coombs’ test, antiglobulin test or AGT) is either of two clinical blood tests used in immunohematology and immunology.
The direct Coombs test is used to test for autoimmune hemolytic anemia; i.e., a condition of a low count of red blood cells (aka RBCs) caused by immune system lysis or breaking of RBC membranes causing RBC destruction.
In certain diseases or conditions, an individual’s blood may contain IgG antibodies that can specifically bind to antigens on the RBC surface membrane, and their circulating RBCs can become coated with IgG alloantibodies and/or IgG autoantibodies. Complement proteins may subsequently bind to the bound antibodies and cause RBC destruction.[1] The direct Coombs test is used to detect these antibodies or complement proteins that are bound to the surface of red blood cells; a blood sample is taken and the RBCs are washed (removing the patient’s own plasma) and then incubated with anti-human globulin (also known as “Coombs reagent”). If this produces agglutination of RBCs, the direct Coombs test is positive, a visual indication that antibodies (and/or complement proteins) are bound to the surface of red blood cells.
The indirect Coombs test is used in prenatal testing of pregnant women and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient’s serum. In this case, serum is extracted from the blood sample taken from the patient. Then, the serum is incubated with RBCs of known antigenicity; that is, RBCs with known reference values from other patient blood samples. If agglutination occurs, the indirect Coombs test is positive.
APRACLONIDINE class similar drug MOA uses SE
- sympathomimetic a2 selective
- brimonidine
- activates a2 adrenergic receptors
a2 decreases secretion of aqueous humor - glaucoma
- bov, xerostomia, hyperemia, pruritus, eye discomfort
