SAS 10: ADRENORECEPTOR AGNOST AND SYMPATHOMIMETIC DRUGS Flashcards by Vina Caroline Romero Darunday

what is the precursor of the effect in symptomatic again?

release of the NE and binding to receptors

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acts as neurotransmitter in adrenergic transmission

Norepinephrine

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a cholinomimetic that acts more like a hormone

Epinephrine

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what is the MOA of direct agonist?

directly interact and activate adrenoreceptor

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what is the MOA of indirect agonist?

enhances the affinity of the endogenous catecholamines

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what are the endogenous cathecholamines?

Dopamine
Norepinephrine
Epinephrine (adrenaline)

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what are the different mechanism of indirect agonist?

> displaces stored catecholamines in the adrenergic nerve ending
inhibits re-uptake of the released catecholamines
prevents the metabolic enzyme in the synaptic cleft

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> displaces stored catecholamines in the adrenergic nerve ending

: what are the mixed sympathomimetics (indirect-acting) that are capable of releasing stored transmitters from noradrenergic nerve endings by a CALCIUM INDEPENDENT PROCESS

tyramine, amphetamine, ephedrine

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> inhibits re-uptake of the released catecholamines

: what are the drugs that can inhibit the NET?

Imipramine(anti-depressant)
cocaine
duloxetine(norepinephrine-serotonin re-uptake inhibitors)

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> prevents the metabolic enzyme in the synaptic cleft

: what are 2 major enzymes responsible for the metabolism in the synaptic cleft

Monoamine oxidase
Catechol-o-methyltransferase

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what type of receptor is Adrenoreceptor

G-coupled receptor

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what are the post-receptor in the adrenergic transmission again?

dopamine, alpha, beta receptors

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what type of G-protein is the a1 receptor?

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what are the effects of a1 receptor?

increase in IP3 and DAG

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what type of G-protein is the a2 receptor?

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what is the effect of a2 receptor?

decrease in cAMP

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what type of G-protein is the beta receptor?

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what type of G-protein is the D1 and D5 receptor?

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what type of G-protein is the D2-D4 receptor?

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if a2 is decrease in cAMP then beta receptor is?

increase in cAMP

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Phenylephrine is what agonist receptor?

a1 receptor

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Clonidine is what agonist receptor?

a2 receptor

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Isoproterenol is what agonist receptor?

Beta receptor

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Does dopamine have an antagonist?

None

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what is IP3 stands for?

1,4,5-triphosphate

This enzyme hydrolyzes polyphosphoinositides, leading to the formation of inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG).

Alpha 1 receptor

This receptors inhibit adenylyl cyclase activity and cause intracellular cyclic adenosine monophosphate (cAMP) levels to decrease.

Alpha 2 receptor

is the major second messenger of the b-receptor activation

Cyclic AMP

what is the CAUSE of the increase in the influx of calcium across the cell membrane and its sequestration inside the cell.

increase in cAMP

is typically associated with the stimulation of adenylyl cyclase

D1 receptor

have been found to inhibit adenylyl cyclase activity, open potassium channels and decrease calcium influx

D2 receptor

a drug may preferentially bind to one subgroup of receptors at low concentration but when at high interact with related class receptors.

selectivity

considers the parent compound of sympathomimetic

Phenylethylamine

what forms a sympathomimetic drugs (known as catecholamines)

-OH substitution in the 3 and 4 positions of the benzene ring

a synthetic catecholamines - very potent b-receptor agonist; little effect on a receptor.

Isoproterenol

The absence of one or the other of these groups, particularly the hydroxyl at C3 without other substitutions on the ring may dramatically, what?

reduce the potency of the drug

why catecholamines is inactive orally?

COMT (metabolic enzyme) is only found in the gut and liver

This increases the bioavailability orally and prolongs action; and, this also increases distribution in the CNS.

absence of one or both -OH in the benzene ring

an increase in the alkyl substituents may, what?

increase B-receptor activity

an increase in the alkyl substituents may, what?

increase B-receptor activity

a substituent to the alpha carbon may, what?

blocks MAO hence, increase activity

alpha carbon-substituent is called

phenylisopropylamines

a substitution in this creates a direct-acting sympathomimetic drugs expect dopamine drug affinity

beta carbon substitution

-leads to arterial and venous vasoconstriction *phenylephrine increases peripheral arterial resistance and decreases venous capacitance. (The ENHANCED ARTERIAL RESISTANCE USUALLY LEADS TO DOSE-DEPENDENT rise in blood pressure.)

activation of alpha 1 receptor

- leads to vasoconstriction when given locally in high dose (or thru IV) - leads to vasodilation when given systematically is activation of what receptor?

a2 receptor

is a nonselective β agonist; it activates both β1 and β2 receptors

Isoproterenol

activation of this receptor results in increased calcium influx in cardiac cell

B-receptor

Pacemaker activity involves?

increase chronotropy and dromotropy

Activation of ____________ IN THE RENAL VASCULATURE may also induce natriuresis.

activiation of D1 receptor

- Dopamine activates β1 receptors in the heart. - At low doses, peripheral resistance may decrease. At higher rates of infusion, dopamine activates vascular α receptors, leading to vasoconstriction.

Dopamine effect

Activation in _______________ in fat cells leads to _____________ with enhanced release of free fatty acids and glycerol into the blood

B adrenoreceptors leads to increased (lipolysis)

inhibit lipolysis by (decreasing) intracellular cAMP

a2 receptor in fat cells

Renin secretion is stimulated by ______ and inhibited by ______________

stimulated by b1; inhibited by a2 receptors

Renin secretion is inhibited by?

Renin secretion is stimulated by?

_______ with INdirect action (eg. amphetamines) readily enters the CNS from circulation which produces varying CNS effects. EFFECTS: mild altering, with improve attention to boring tasks; through elevation of mood, insomnia, euphoria, and anorexia; to either full-blown psychotic behavior

noncatecholamines

an agonist at both α and β receptors

Epinephrine

- examples are Levarterenol, noradrenaline - agonist at both α1 and α2 receptors

Norepinephrine

*the immediate precursor of norepinephrine

Dopamine

DIRECT-ACTING SYMPHATHOMIMETICS: has a longer duration of action than the catecholamines. It is an effective mydriatic and decongestant and can be used o raise the blood pressure.

Phenylephrine *Methoxamine

- prodrug that is enzymatically hydrolyzed to desglymidodrine, a selective α1-receptor agonist - the drug may treat hypotension but causes hypertension when laying

Midodrine

acts pharmacologically like *phenylephrine (predominantly a1 agonist)

Methoxamine

Clonidine, methyldopa, guanfacine, and guanabenz are examples of

A2 selective agonist

DEXmedetomidine

sedation of //initially// intubated/ and /mechanically/ ventilated patients during treatment in an intensive care setting.

DEXmedetomidine

used as a central muscle relaxant

TIZAnidine

central muscle relaxant

Topical decongestants

Xylo-line, Oxy-line XYLOmetazoLINE and OXYmetazoLINE

Dobutamine

resembles dopamine but binds to a and b receptors

first orally active sympathomimetic drug found in Ma huang, a popular herbal medication.

Ephedrine

Ma huang, herbal

Ephedrine

component of many decongestant mixtures. *pseudo

pseudoephedrine

Phenylpropanolamine

common component in OTC appetite suppressants

Common, OTC *P

Phenylpropanolamine

similar to amphetamine but with higher ratio of central to peripheral actions *meth

methamphetamine

a variant of phenylisopropylamine with amphetamine-like effects. It has been promoted as an anorexiant and is also a popular drug of abuse.

Phenmetrazine

an amphetamine variant whose major pharmacologic effects and abuse potential are similar to those of amphetamine. -effective in children with ADHD

Methylphenidate

is psychostimulant that differs from amphetamine

Modafinil

byproduct of Tyrosine metabolism

Tyramine

Amphetamine, Methamphetamine, Phenmetrazine, Methylphenidate, Modafinil, Tyramine are example of what

Indirect-acting symphathomimetics

Atomoxetine, Reboxetine, Sibutramine, Duloxetine, Cocaine are example of what?

Catecholamine reuptake inhibitor

Fenoldopam and Levodopa are examples of what?

Dopamine agonist

why catecholamines cannot be given orally?

because they are greatly degraded in the liver and gastrointestinal mucosa. In contrary to non-catecholamines.