Adrenergic and anti-adrenergic drugs.ppt
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1、Adrenergic and anti-adrenergic drugs,By Linda Self NUR 3703,Divisions of human nervous system,Nervous system,Sympathomimetic or adrenergic in sympathetic nervous systemneurotransmitters are _ Parasympathomimetic or cholinergic are used to describe parasympathetic systemneurotransmitter is _,Sympathe
2、tic nervous system,Fight or flight response results in: Increased BP Increased blood flow to brain, heart and skeletal muscles Increased muscle glycogen for energy Increased rate of coagulation Pupil dilation,Adrenergic receptors,AlphaA1 and A2 BetaB1, B2, B3 Dopaminesubsets D1-5,Review of functions
3、 of sympathetic nervous system receptors,Alpha 1smooth muscle contraction Alpha 2-negative feedback causes less norepinephrine to be released so BP is reduced Beta 1increased heart rate Beta 2bronchodilation Beta 3actual site for lipolysis,Mechanisms of action and effects of adrenergic drugs,Direct
4、adrenergic drug action Affects postsynaptic alpha 1 and beta receptors on target effector organs Examples: epinephrine, Isuprel, norepinephrine, phenylephrine,Mechanisms of action cont.,2. Indirect adrenergic drug action occurs by stimulation of postsynaptic alpha 1, beta 1 and beta 2 receptors.Caus
5、e release of norepinephrine into the synapse of nerve endings or prevent reuptake of norepinephrine. Examples include cocaine and TCAs,Mechanisms of action cont.,3. mixed action. Combination of direct and indirect receptor stimulation Examples are ephedrine and pseudoephedrine,Mechanisms of action c
6、ont.,Stimulation of alpha 2 receptors in CNS is useful in decreasing BP Most body tissues have both alpha and beta receptors Effect occurs 2ndary to receptor activated and number of receptors in the particular body tissue,Mechanisms of action cont.,Some drugs act on both receptors-dopamine Some are
7、selective-Isuprel,Indications for use,Emergency drugs in treatment of acute cardiovascular, respiratory and allergic disorders In children, epinephrine may be used to treat bronchospasm due to asthma or allergic reactions Phenylephrine may be used to treat sinus congestion,Indications of adrenergics
8、 cont.,Stokes Adams Shock Inhibition of uterine contractions For vasoconstrictive and hemostatic purposes,Contraindications to use of adrenergics,Cardiac dysrhythmias, angina pectoris Hypertension Hyperthyroidism Cerebrovascular disease Distal areas with a single blood supply such as fingers, toes,
9、nose and ears Renal impairment use caution,Individual adrenergic drugs,Epinephrineprototype Effects include: increased BP, increased heart rate, relaxation of bronchial smooth muscle, vasoconstriction in peripheral blood vessels,epinephrine,Increased glucose, lactate, and fatty acids in the blood du
10、e to metabolic effects Increased leukocyte and increased coagulation Inhibition of insulin secretion,epinephrine,Affects both alpha and beta receptors Usual doses, beta adenergic effects on heart and vascular smooth muscle will predominate, high doses, alpha adrenergic effects will predominate Drug
11、of choice for bronchospasm and laryngeal edema of anaphylaxis,epinephrine,Excellent for cardiac stimulant and vasoconstrictive effects in cardiac arrest Added to local anesthetic May be given IV, inhalation, topically Not PO,epinephrine,Physiologic antagonist to histamine Those on beta blockers may
12、need larger doses Drug of choice in PEA. Vasopressin has now become drug of choice in ventricular tachycardia Single dose of Vasopressin, 40 units IV,Other adrenergics,Ephedrine is a mixed acting adrenergic drug. Stimulates alpha and beta receptors. Longer lasting than epinephrine. See in Primatene
13、mist,Pseudophed,Used for bronchodilating and nasal decongestant effects,isuprel (Isoproterenol),Synthetic catecholamine that acts on beta 1 and 2 receptors Stimulates heart, dilates blood vessels in skeletal muscle and causes bronchodilation No alpha stimulation Used in heart blocks (when pacemaker
14、not available) and as a bronchodilator,Neosynephrine (Phenylephrine),Pure alpha Decreases CO and renal perfusion No B1 or B2 effects Longer lasting than epinephrine Can cause a reflex bradycardia Useful as a mydriatic,Toxicity of adrenergics in critically ill patients,Affects renal perfusion Can ind
15、uce cardiac dysrhythmias Increases myocardial oxygen consumption May decrease perfusion of liver Tissue necrosis with extravasation,Toxicity,Do not give epinephrine and Isuprel at same time or within 4 hours of each other. Could result in serious dysrhythmias.,Anti-adrenergics,Sympatholytic Block or
16、 decrease the effects of sympathetic nerve stimulation, endogenous catecholamines and adrenergic drugs,Antiadrenergic smechanisms of action and effects,Can occur by blocking alpha 1 receptors postsynaptically Or by stimulation presynaptic alpha 2 receptors. Results in return of norepineprhine to pre
17、synaptic site. Activates alpha 2 resulting in negative feedback. Decreases release of additional norepinephrine.,Alpha-Adrenergic Agonists and blocking agents,Alpha 2 agonists inhibit release of norepinephrine in brain; thus, decrease effects on entire body Results in decrease of BP Also affects pan
18、creatic islet cells, thus some suppression of insulin secretion,Alpha 1 adrenergic blocking agents,Act on skin, mucosa, intestines, lungs and kidneys to prevent vasoconstriction Effects: dilation of arterioles and veins, decreased blood pressure, pupillary constriction, and increased motility of GI
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