Sympathomimetics Flashcards
Where are most alpha-2 receptors located?
On the presynaptic terminal
Are catecholamines water soluble or water insoluble?
Water soluble
Norepinephrine
Catecholamine, direct on A1 and A2, less on some B1
Epinephrine
Catecholamine, direct on A1, A2, B1, B2
Isoproterenol
Catecholamine direct on B1 and B2
Dopamine
Catecholamine direct on A1,B1,B2 and DA (renal vessels)
Dobutamine
Catecholamine, direct on B1, others
Phenylephrine
Non-catecholamine, direct on A1
Tetrahydrozoline
Non-catecholamine, direct on A1
Nephazoline
Non-catecholamine, direct on A1
Oxymetazoline
Non-catecholamine, direct on A1
Ritodrine
Non-catecholamine, direct on B2 more than B1
Metaproterenol
Non-catecholamine, direct on B2 more than B1
Albuterol
Non-catecholamine, direct on B2 more than B1
Salbutamol
Non-catecholamine, direct on B2 more than B1
Salmeterol
Non-catecholamine, direct on B2 more than B1
Formoterol
Non-catecholamine, direct on B2 more than B1
Terbutaline
Non-catecholamine, direct on B2 more than B1
Clonidine
Non-catecholamine, direct on A2
Ephedrine and pseudoephedrine
Non-catecholamine, indirect on a and b (increased release)
Amphetamine
Non-catecholamine, indirect on a and b (increased release)
Cocaine
Non-catecholamine, indirect on a and b (decreased uptake)
Tyramine
Non-catecholamine, indirect on a and b
What suffix is commonly associated with beta-agonists?
ol
What response do blood vessels give to alpha-beta agonists at different concentrations?
Low concentration - beta response, high concentration - alpha response
Which sympathomametics cross the blood brain barrier well and why?
Amphetamine and ephedrine because they do not have OH groups (they cause CNS stimulation in the brain)
Which isomer is more potent in sympathomimetics
L-isomer in periphery, d-isomer in CNS
What chemical change increases a drugs beta activity?
N-alkylation
A botched IV infusion with a type of sympathomimetic can damage tissue. What type and why?
Alpha agonist. Because they cause BV constriction, if they end up the tissue you can get necrosis
What happens to catecholamines if exposed to air?
Solution can turn pink, drug has deteriorated
Give the effects of an alpha1 agonist on the lung, GI, Heart, BVs, Eye, Uterus, Glands, Liver, Pancreas, Skeletal muscle, and CNS
Lungs - none, GI - decreased activity, Heart - none, BVs - constriction, Eye - Mydriasis, Uterus - none, Glands - secretion, Liver - Glycogenolysis, gluconeogenesis, Pancreas - none, Skel muscle - none, CNS - alertness
Give the effects of a beta1 agonist on the lung, GI, heart, BVs, eye, uterus, glands, liver, pancreas, skel muscle, CNS, and kidney
Lung - none GI - none, Heart - Increased HR, contract, velocity, BVs - none, Eye - increased inflow, uterus - none, glands - none, liver - none, pancreas - none, skel muscle - none, CNS - fatigue, hunger, kidney - renin
Give the effects of a beta2 agonist on lungs, GI, heart, BVs, Eye, uterus, glands, liver, pancreas, skel muscle, CNS, and kidney
Lungs - Bronchorelaxation, GI - decreased activity, heart - increased HR, contract, velocity (less than B1), BVs - dilation, eye - increased inflow, uterus - relaxtion, glands - none, liver - glycogenolysis and gluconeogenesis, pancreas - insulin secretion increased, skel muscle - increased activity, CNS - fatigue, hunger, kidney - renin
What is the only end organ effect of alpha2 agonism?
Decreased insulin secretion from the pancreas
Why is hyperthyroidism a contraindication for beta agonists?
Because T3 regulates B2 receptors on heart (increases their sensitivity)
Why is Raynauds disease a contraindication for alpha agonists?
Because the blood vessels are already constricted in Raynauds and alpha agonists constrict them more
What type of sympathomimetic increases blood glucose?
B2 agonists (this is despite an increase in insulin secretion that occurs with B2 agonism)
Give the effect of norepinephrine on blood pressure and the reason for this effect
Increase diastolic, smaller increase in systolic and MBP. Due to increase in peripheral resistance
Give the effect of epinephrine on blood pressure and the reason for this effect
Increase systolic, diastolic no change, increase MBP. Due to increase in HR and CO
Give the effect of isoproterenol on blood pressure and the reason for this effect
Increase systolic, decrease diastolic and mean (Peripheral Resistance decreases, CO up initially but down due to pooling)
Give the effect of dopamine on blood pressure and the reason for this effect
Increase systolic, no change in diastolic, increase MBP. Due to increase HR and CO (no change in resistance except for renal dilation)
Three vascular uses of alpha agonists
Nasal decongestion, stopping superficial bleeding, prevent spread of local anesthetic
What drug is given for CHF and why?
Dobutamine (a selective B1 agonist). Has fewer other effects while having the desired effect (increased CO)
What does histamine cause during anaphylactic shock and what is given to combat this (explain why)
Histamine causes bronchoconstriction and vasodilation. Epinephrine is given to combat that (alpha and beta agonist) because it causes bronchorelaxation (B2) and vasoconstriction (A1)
What is the mechanism of open angle glaucoma and what is given to combat this?
Problem with outflow so give a parasympatheticomimetic to contract the cilliary body and increase ourflow or a beta antagonist to decrease inflow.
What autonomic drug might you give to reduce premature contractions?
A beta 2 agonist
