M2: Adrenoreceptor Agonist Drugs Flashcards
Receptors: formation of inositol 1,4,5 triphosphate (IP3) and diacylglycerol (DAG). Phenylephrine
Alpha 1
Drugs that mimics norEpi & Epi
Sympathomimetic drugs
Receptors: Inhibition of adenyl cyclase. Decrease cAMP levels.
Alpha 2
Drugs that acts on Alpha 2 receptors
Clonidine/Catapress
Stimulation of adenyl cyclase and increase conversion of ATP to cAMP
Beta receptors (1,2,3)
Agonists of B receptors
Isoproterenol, Dobutamine & Albuterol
Dopamine Receptors: stimulation of adenyl cyclade and increase camp
D1
Dopamine Receptors: inhibit adenyl cyclase activypity. Decrease in cAMP.
D2
Example of D2 receptor drugs. For excessive lactation.
Bromocriptine
Widespread distribution of A & B receptors in the heart and blood vessels. Effect on BP: effects on HR, myocardial function, peripheral vascular resistance & venous return.
Cardiovascular System
Widely expressed in vascular beds. Arterial and venoconstruction. Inc peripheral resistance and dec venous capacitance. Heart: modest positive inotropic(contractility) response.
Alpha 1 receptor activation
Present in the vasculature. Vasoconstriction: locally, rapid IV & very high oral dose.
Alpha 2 receptor activation
Heart: increased contractility and HR. Inc cardiac output. Vasodilation: decreased peripheral resistance.
Beta receptor activation
IV admin: vasodilation of renal, splanchnic, coronary, cerebral vessels (at low doses). Heart: activation of B1 receptors. Kidneys: inc perfusion. Inc urine output. But in high doses may lead to vasoconstriction (for hypotension) maintain renal dose
Dopamine Receptor activation
Activation of B2 receptors, relaxation of bronchial smooth muscles & bronchodilation. Name the organ.
Lungs
Affect Beta receptors in the heart and spare those of the lungs
Cardioselective Beta Blockers
Alpha receptor stimulation: pupillary dilatation and inc in the. Outflow of aqueous humor leading to dec in intraoccular pressure
Eyes
Alpha receptor stimulation: contraction of bladder and urethral sphincter then urinary continence. A receptor activation in ductus deferens & seminal vesicle
GUT
In metabolism, leads to lipolysis then release of FA & glycerol in the blood. Glycogenolysis leads to inc glucose release.
B receptor activation
B adrenergic stimulation: inc uptake of potassium in the cells
Hypokalemia
B adrenergic stimulation: _________ insulin secretion
Increase
Alpha 2 receptor activation: _________ insulin secretion
Decrease
Stimulates renin secretion
B1
Inhibits renin secretion
A2
Both alpha & beta agonist. Vasoconstrictior and cardiac stimulant, increase in systolic BP. Vasodilation in blood supply of skeletal muscle. Inc blood flow during exercise.
Epinephrine
Agonist of both alpha1 & apha2 receptors. Increase peripheral resistance. Increase systolic and diastolic BP.
NorEpi
Immediate precursor in the synthesis of NorEpi. Impt neurotransmitter in the brain.
Dopamine
Deficiency of dopamine in the basal ganglia
Parkinson’s Dse
Targets for antipsychotic drugs
Dopamine receptors
Pure alpha1 agonist. Not inactivated by COMT leads to longer duration of action than catecholamines. Used as a mydriatic and decongestant and can be used to raise the BP. Do not give OTC prep for HPN patients.
Phenylephrine
Prodrug. Enzymatically hydrolyzed to desglymidodrine (selective A1 receptor agonist) for treatment of orthostatic hypotension due to impaired ANS function.
Midodrine
Acts pharmacologically as phenylephrine via A1 stimulation. Causes prolonged inc in BP and vagally mediated bradycardia. Clinical application is rare & limited to hypotensive states.
Methoxamine
Ability to decrease BP through actions in the CNS leading to hypertension treatment
Clonidine, methyldopa, guanfacine & guanabenz
For sedation of initially intubated and mechanically ventilated patients.
Dexmedetomidine
Drug of choice for pre eclampsia. Only one safe to use.
Methyldopa
May lead to rebound hypertension
Clonidine
Definitive management of pre eclampsia
Termination of pregnancy
Ability to promote constriction of the nasal mucosa. Topical decongestants.
Xylometazoline & Oxymetalozine
May cause hypotension when taken in large doses
Oxymetazoline
Potent beta receptor agonist. Positive chronotropic and inotropic actions. Exclusive B receptor agonist that leads to potent vasodilation to inc CO.
Isoproterenol
Beta1 selective agonist. Chemical structure resembles dopamine, for hypotension. Specific to Positive inotropic action. Won’t vasoconstrict the vessels. Usually administered with dopamine.
Dobutamine
First orally active sympathomimetic drug. Ma huang plant. High bioavailability and long duration of action. Mild stimulant; used earlier in asthma. Vasodilation.
Ephedrine
Components of decongestants. Used in manufacture of methamphetamine.
Pseudoephedrine
Component in over the counter appetite suppressants; decongestants. Use was associated with hemorrhagic strokes in young women. Can inc BP.
Phenylpropanolamine
Used and misused as a CNS stimulant. Same with ephedrine. Marked stimulant effect on mood and alertness and depressant on appetite. Action is mediated through the release of NorEpi.
Amphetamine
Variant of amphetamine. Same pharmacologic effect with amphetamine. Used in ADHD in children. Given 6hrs before bedtime.
Methylphenydate
Increases concentrations of epi, dopa, sero and glutamate while dec GABA. To improve wakefulness in narcolepsy. May cause inc BP & HR.
Modafinil
Normal byproduct of tyrosine metabolism. Found in fermented foods; cheese, sausage & all. May caused marked increase in blood pressure when taken with MAO(depression) inhibitors.
Tyramine
Selective inhibitor of NE reuptake transporter. For ADHD. May cause orthostatic tachy
Atomoxetine
Serotonin & NE reuptake inhibitor. Only FDA approved appetite suppressant for long term treatment of obesity.
Sibutramine
Local anesthetic. Inhibition of dopamine reuptake in the pleasure centers of the brain. Smoked, snorted into the nose & injected. Produces amphetamine like psychological effect but shorter in terms if duration. More intense.
Cocaine
Converted to dopamine in the body. Treatment of PD.
Levodopa
D1 receptor agonist. Peripheral vasodilation in some vascular bed. Given IV. For severe HPN.
Fenoldapam
Use of sympathomimetics when there is no immediate threat to patient. NoEpi, Phenylephrine & Metoxamin
Acute hypotension
Associated with hypotension, altered mental status, oliguria and metabolic acidosis.
Shock
Mainstays of treatment for shock
Volume replacement & tx of underlying cause
Positive inotropic agents (dopa & dobu) for shorter relieve of symptoms
Cardiogenic shock
Use of vasoconstrictor may improve corononary perfusion but will inc
O2 demand
Reflex sympathetic activation with inc HR & peripheral vasoconstriction
Chronic Orthostatic Hypotension
Chronic Orthostatic Hypotension tx
Inc peripheral resistance
Temporary emergency management give isoproterenol & Epi
Complete heart block & cardiac arrest
Redistribution of blood flow to the coronaries and to the brain during CPR
Epi
Are safer and effective for heart blocks
Pacemaker
For inducing local vasoconstriction during surgery. Achieving hemostasis, reduce local anesthetic and mucus membrane congestion.
Cocaine & Epi
Non selective: epi. Beta selective agent: isoprotenol. Beta 2 selective agents: albuterol, metaproterenol & terbutaline (mainstay tx)
Bronchial asthma
Anaphylaxis: bronchospasm, congestion of mucus membranes, angioedema & severe hypotension.
Epi. 0.3-0.5mg initial tx then glucocorticoid & histamine
For mydriasis
Phenylephrine
For patient’s with glaucoma
Apraclonidine
GUT: tocolytic agents. Slow down uterine muscle contraction. For preterm labor
Ritodrine & Terbutaline
GU: for stress incontinence
Ephedrine/Pseudo
CNS: for narcolepsy
Amphetamine & Modafinil
For HPN, diarrhea in diabetic patients with autonomic neuropathy. For alcohol & narcotic withdrawal. For menopausal women with hot flushes.
Clonidine
