Introduction to Pharmacology Adrenergic Blockers NRSB 311 Nervous

Introduction to Pharmacology Adrenergic Blockers NRSB 311

Nervous System • Central Nervous System (CNS) Peripheral Nervous System (PNS) is divided into v Somatic Nervous System (SNS) Control voluntary functions such as skeletal System v Autonomic Nervous System (ANS) Controls those body functions for which you have no control such as heart lungs, digestion)

Autonomic Nervous System

Autonomic Nervous System Parasympathic System (Actyl. Cholinergics) • PSNS ▫ Restorative responses ▫ Rest and recreation ▫ Neurotransmitter v acetylcholine Sympathetic System (Adrenergic) SNS �Fight of Flight �Responses are self protected when faced with dangerous situation �Neurotransmitters – Catacholamines v Epinephrine v Norepinephrine v Dopamine

Sympathetic Nervous System • SNS is activated via neurotransmitters q. The three main neurotransmitters for the SNS are: Norepinephrine, Epinephine and Dopamine q These three neurotransmitters are call Catecholamine

Sympathetic Nervous System q Receptor sites that are affected by the neurotransmitters epinephrine and norepinephrine are called Adrenergic receptors: (they are located throughout the tissue and organs of the body) q Adrenergic Receptors are divided into two groups: �Alpha –Adrengic receptor Alpha 1 Alpha 2 �Beta – Adrengic receptor Beta 1 Beta 2 q. Receptor sites that are affected by the neurotransmitters dopamine are called dopaminergic receptors

Alpha Receptors • Overall effect of alpha receptors stimulation = vasoconstriction and CNS stimulation • Stimulation causes: ▫ ▫ ▫ Vasoconstriction (peripheral blood vessels) Smooth muscle relaxation (Decrease GI motility) Pupil dilation( by constricting the sm blood vessels in eye) Decreased insulin release Bladder Sphincter Constriction

Beta Receptors • Beta 1 – heart ▫ Stimulation causes: �Increase force of contraction �Increase in heart rate �Increase in conduction of nerve impulse through the SA/AV node • Beta 2 – lungs ▫ Stimulation causes: �Bronchodilation

Adrenergic Drugs • Drugs that have similar or mimic the effects of the SNS neurotransmitters (Norepinephrine, Epinephine and Dopamine) are referred to as adrenergic agonist or Sympathamimetics • Adrenergics drugs : stimulate adrenergic receptors causing increased sympathetic action

Adrenergic Blockers • Adrenergic Antagonists or Adrenergic sympatholytics: These drugs interrupt the stimulation of the SNS. • Blocks responses in two ways ▫ Competitive : The drugs as a greater affinity for the receptor that the neurotransmitter ▫ Noncompetitive : Makes the receptor less responsive to the neurotransmitter Mechanism of action depends on selectivity for receptors in particular tissues or cells in the body

Adrenergic Blockers • Alpha blockers result in ▫ ▫ ▫ Vasodilation ( Peripheral Vessels) Decreased blood pressure Pupil constriction (miosis) Suppressed ejaculation Reduce bladder sphincter constriction

Alpha Blockers • Indications ▫ Hypertension ▫ Migraines ▫ BPH (investigational) • Contraindications • Adverse Effects • Interactions