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level: Level 2

Questions and Answers List

level questions: Level 2

Question	Answer
Tissues may become less responsive to further stimulation by a given agonist after long exposure from it	Desensitization other terms denoting desensitization: tolerance, refractoriness, tachyphylaxis
refers to loss of responsiveness EXCLUSIVELY of the receptors that have been exposed to repeated or sustained activation by the agonist	Homologous desensitization
refers to the process by which desensitization of ONE RECEPTOR by its agonists also results in desensitization of another receptor that has not been directly activated by the agonist in question.	Heterologous desensitization
• Natural catecholamines • Norepinephrine, Epinephrine, Dopamine • Higher affinity at BETA receptors than alpha receptors LOW DOSE: beta effect HIGH DOSE: alpha effect Epinephrine: B1 = B2 >> a1 Norepinephrine: B1 > a1 Dopamine: D1 > B1 >> a1 • Undergo EXTENSIVE FIRST PASS EFFECT • Route of administration: IV, inhalational, SC	NON- SELECTIVE DIRECT ACTING SYMPATHOMIMETICS
- ADRENALINE - an AGONIST at both alpha and beta-receptors - a very potent vasoconstrictor and cardiac stimulant (also increase renin release) • 1st line for anaphylaxis • Local vasoconstrictor with Lidocaine	EPINEPHRINE
- AGONIST at both ALPHA 1 and 2 receptors - also has effect on beta 1 receptors but its effect on beta 2 receptors are not as much as epinephrine = NO USE IN ASTHMA and ANAPHYLAXIS •1st line agent for SEPTIC SHOCK • Used to treat SHOCK	NOREPINEPHRINE - Levarterenol, noradrenaline (Levophed®)
- the immediate precursor in the synthesis of NE - important in sodium excretion and renal function - an important neurotransmitter in the central nervous system and involved in the reward stimulus relevant to addiction - Deficiency in ganglia: PARKINSON'S DISEASE (Levodopa) - INCREASED level: Psychosis - DOC for CARDIOGENIC and SEPTIC SHOCK - SUPERIOR than NE because of increased blood flow in the kidneys - Used to treat HYPOTENSION and SEVERE HEAR FAILURE	DOPAMINE
- very potent B-receptor agonist and has LITTLE EFFECT on alpha-receptors - has positive inotropic and chronotropic actions; potent vasodilator and bronchodilator - Historical use: management of BRONCHIAL ASTHMA	ISOPROTERENOL - Isoprenaline, Isuprel®
found in blood vessel --> Vasoconstriction and increase BP	ALPHA 1 AGONISTS - MIDODRINE - PHENYLEPHRINE - METHOXAMINE
- a prodrug that is enzymatically hydrolyzed to desglymidodrine, a selective alpha-1 receptor agonist - used for the treatment of ORTHOSTATIC HYPOTENSION - Toxicity: Supine hypertension, piloerection, urinary retention ALPHA 1 AGONIST	MIDODRINE
- not a catecholamine, thus, NOT INACTIVATED by COMT - used to treat HYPOTENSION in hospitalized & surgical patients - an effective MYDRIATIC and DECONGESTANT and can be used to RAISE the blood pressure ALPHA 1 AGONIST	PHENYLEPHRINE
- acts like phenylephrine - may cause PROLONGED increase in blood pressure due to vasoconstriction ALPHA 1 AGONIST	METHOXAMINE
ALPHA 1 AGONISTS TOXIC EFFECT:	• Local (intranasal) • Rhinitis medica mentosa (rebound congestion); used for nmt 3 days • Systemic • Exacerbation of hypertension • Urinary retention BPH • Tolerance; used for nmt 5 days