Adrenoceptor blocking drugs

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Adrenoceptor blocking drugs. Classification:depend on the affinity for different groups of receptor α-adrenoceptor antagonists β-adrenoceptor antagonists α, β-adrenoceptor antagonists Adrenaline reversal. α-R blocking agents. reversible α-R blocking agents Phentolamine Tolazoline - PowerPoint PPT Presentation

Transcript of Adrenoceptor blocking drugs

  • Adrenoceptor blocking drugs

  • Classification:depend on the affinity for different groups of receptor-adrenoceptor antagonists-adrenoceptor antagonists, -adrenoceptor antagonistsAdrenaline reversal

  • -R blocking agentsreversible -R blocking agentsPhentolamineTolazolineirreversible -R blocking agents phenoxybenzamine

  • Phentolamine and Tolazoline

    Binds to -R, producing an reversible blockage

    competitive antagonists

  • Pharmacological Effectsproduces vasodialation, decrease peripheral resistance and increase venous capacityreflex cardiac stimulationstimulates salivary, lacrimal, pancreatic , respiratory tract and gastric secretion

  • Therapeutic UsesPeripheral vascular diseasecontrol acute hypertension episodes caused by use of sympathemimeticsdiagnostic test for pheochromocytomaAntishockheart failure with pulmonary edema

  • Adverse reactionsHypotensionGastrointestinal reactionsarrhythmia

  • Phenoxybenzaminebinds to the -R, producing an irreversible blockage, more potent in blocking -R a little effects on His-R and 5-HT-R

  • Pharmacological Effectsproduce vasodialation, decrease peripheral resistancediastolic pressure decreasereflex cardiac stimulationa little effects on His-R and 5-HT-R

  • Therapeutic UsesPeripheral vascular diseaseAntishockpheochromocytomaBPH

  • 1-R blocking agentsSelectively block 1-RPrazosin, terazosin, tamsulosin, doxazosinTherapeutic Uses: hypertension, BPH

  • 2-R blocking agentsSelectively block Presynaptic 2-R, regulation in Periphery and CNS NAYohimbine

  • -R blocking agentsblock the neurotransmitter and adrenomimetic drugs from adrenergic nerve ending to bind with -R competitive antagonistsnonselective -R antagonist:competes for both 1-R and 2-R1-R antagonist

  • Pharmacological EffectsCardiovascular systemdecrease the heart rate and cardiac output and prolongs systoledecrease the blood flow to most tissuedecrease the total coronary blood flow and oxygen consumption

  • Pharmacological EffectsBronchial smooth muscleincrease airway resistance by -R blockade

    Metabolism: carbohydrate and fat metabolism are mediated by -R

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  • Pharmacological Effectsmembrane-stabilization action : quinidine like action and local anesthesia actionintrinsic sympathomimetic activity(ISA)Antiplatelet, ocular pressure reduction

  • Therapeutic Usestachycardia supraventricular and ventricular arrythmias, especially for sinus tachycardiaangina pectoris, myocardial infarctionHypertensionBHFOthers: Hyperthyroidium

  • Adverse reactionsCardiovascular systemAsthmaWithdrawal reactionOthers:Contraindication: Bradycardia, cardiac function insufficiency, severe A-V blocking, asthma

  • PropranololBioavailability: 30%Interindividual variation HR , cardiac output ,BPTherapeutic Uses: arrythmias, hypertension, angina pectoris, hyperthyroidism

  • other-R antagentsNadolol: more potent than propranolol, and half life are longerTimolol: most potent, glaucomaPindololmore potent than propranololISA(2-R)

  • 1-R blocking agentsAtenolol, metoprololLittle effect on 2-Rhypertension

  • -R blocking agentsLabetalol, bucindolol, arotinolol, amosulalolMore potent in blocking -RMajor use in hypertension

  • LabetalolBioavailability: 20-40%ISA to 2-RTherapeutic Uses: hypertension, angina pectoris

  • arotinilol:=1:8contractility decrease, HRBPTherapeutic Uses: hypertension, Supraventricular tachycardia, angina

  • 1 spdp spdp

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