Sympathomimetic Agents - PowerPoint PPT Presentation

1 / 37
About This Presentation
Title:

Sympathomimetic Agents

Description:

Chief chemical neurotransmitter at the post-ganglionic ... Pre-operative drying of secretions. Sympathetic Effects. Organ Site. Heart. SA Node. Contractility ... – PowerPoint PPT presentation

Number of Views:749
Avg rating:3.0/5.0
Slides: 38
Provided by: jimc199
Category:

less

Transcript and Presenter's Notes

Title: Sympathomimetic Agents


1
Sympathomimetic Agents
  • By Jim Clarke

2
The Nervous System
  • Autonomic Control
  • Sympathomimetic side
  • Chief chemical neurotransmitter at the
    post-ganglionic sites is nor-epinephrine
  • Chief chemical neurotransmitter at the
    pre-ganglionic sites is acetylcholine
  • Parasympathomimetic side
  • Chief chemical neurotransmitter is acetylcholine
  • Somatic Control
  • Motor control is mediated at the target organ by
    acetylchline

3
Diagram of Central Peripheral Nervous System
4
How 2 Branches Differ
  • Adrenergic
  • Fight or Flight
  • Gearing system up
  • Increases glycogen breakdown
  • Improves blood flow to major muscles heart
  • Dilates the eyes
  • Fast acting very widespread
  • Cholinergic
  • Feed or Bread
  • Increases digestive functions
  • Increases urinary function
  • Increases bronchial secretions
  • Slower acting more focused

5
Nerve Signal Transmission
  • Efferent limbs of nerves transmit impulses from
    the brain or spinal cord to the target organ
  • Afferent limbs of nerves transmit impulses from
    the organ system to the brain and spinal cord

6
Sympathetic Characteristic
  • Sympathetic branch arises from thoraco-lumbar
    portion of the spinal cord
  • Postganglionic fibers may stimulate many sites
  • adrenal gland heart lungs liver
  • sympathetic stimulation causes widespread effects
    because of the action of the adrenal gland on the
    entire body

7
Parasympathetic Characteristics
  • Arises from the cranio-sacral portions of spinal
    column
  • Postganglionic fibers are able to closely target
    effector sites (heart lungs gut)
  • Effects tend to be limited to the effector sites
    and are not widely distributed

8
Parasympathetic Effects
  • Organ Site
  • Heart
  • SA Node
  • Contractility
  • Conduction Velocity
  • Bronchi
  • Smooth Muscle
  • Mucous glands
  • Cholinergic Effect
  • Slowing of rate
  • Decreased Atrial force
  • Decreased conduction
  • Bronchoconstriction
  • Increased mucus production

9
Parasympathetic Effects
  • Effect
  • No direct effect
  • Vasodilation
  • No effect
  • No effect
  • Organ Site
  • Vascular Smooth Muscle
  • Skin Mucosa
  • Pulmonary
  • Skeletal muscle
  • Coronary

10
Cholinergic Receptors
  • Muscarinic Receptors are located at
  • exocrine glands (bronchial glands)
  • cardiac muscles
  • GI tract smooth muscle
  • Acetylcholine working at these sites produce
    Muscarinic effects
  • Increase in secretions may occur when drugs
    effecting these lung sites are given

11
Cholinergic Receptors
  • Nicotinic Receptors are located at autonomic
    ganglia and in skeletal muscles
  • Stimulation of these receptors cause increases in
    blood pressure and muscle tremors

12
Parasympathetic Agents
  • Indirect acting agents inhibit the action of
    cholinestarase. This increases the action of
    the remaining acetylcholine
  • Reversible inhibitors neostigmine (Prostigmine)
    edrophonium (Tensilon) pryridostigmine
    (Mestinon)
  • These agents are used to either reverse the
    actions of certain other drugs or to test the
    bodys ability to increase muscle strength

13
Parasympathetic Agents
  • Irreversible inhibitors - these are primarily the
    organophosphate pesticides (Malathion Diazanon
    Parathion) except for
  • Phospholine - used as a pupillary constrictor in
    the treatment of glaucoma
  • Atropine can be used to reverse the effects of
    both reversible and irreversible inhibitors.
    The have limited effect on organophosphates
  • Protopam may be used in first 24 hours to treat
    pesticide poisoning

14
Parasympatholytic Agents
  • These agents block acetylcholine receptors at the
    neuroeffector site
  • Atropine is the common agent in this group
  • Used to accomplish the following
  • Bronchodilation
  • Antidiarrhea
  • Tx of bradycardia
  • Pre-operative drying of secretions

15
Sympathetic Effects
  • Organ Site
  • Heart
  • SA Node
  • Contractility
  • Conduction Velocity
  • Bronchi
  • Smooth Muscle
  • Mucous glands
  • Effect
  • Increasing of rate
  • Increased Atrial force
  • Increased conduction
  • Bronchorelaxation
  • Increased secretion

16
Sympathetic Effects
  • Effect
  • Vasoconstriction
  • Dilation/Constriction
  • Dilation
  • Dilation/Constriction
  • Organ Site
  • Vascular Smooth Muscle
  • Skin Mucosa
  • Pulmonary
  • Skeletal muscle
  • Coronary

17
Inactivation of Adrenergic Agents
  • Catechol-O-methyl Transferase (COMT)
  • deactivates adrenergic agents called
    catecholamines by changing one of the side-groups
    on the cathechol ring
  • Mono Amine Oxidase (MAO)
  • deactivates adrenergic agents by removing the
    amine group from the side-chain
  • Since MAO is found in the stomach, many
    adrenergics cannot be orally administered

18
Alpha Beta Receptors
  • Alpha receptors - generally excite (except in GI
    tract in the CNS where inhibition or relaxation
    occurs)
  • Alpha 1 and Alpha 2 receptors
  • Beta Receptors - generally inhibit or relax
    (except in the heart ---gt stimulation)
  • Beta 1 and Beta 2 receptors

19
Adrenergic Receptor Locations
  • Receptor Type
  • Alpha 1
  • Alpha 2
  • Beta 1
  • Beta 2
  • Beta 3
  • Location
  • Peripheral blood vessels
  • Presynaptic receptors
  • Heart
  • Smooth Muscle cardiac muscle
  • Lipocytes

20
Key Aspects of Receptors
  • Alpha 1 and Beta 1 receptors excite
  • Alpha 2 and Beta 2 receptors inhibit

21
Receptor Locations Actions
  • Alpha 1 receptors are located at the
    post-synaptic smooth muscle are excitatory
  • Alpha 2 receptors are located at the pre-synaptic
    ganglia are inhibitory

22
Adrenergic Control in the Lungs
  • There is no direct adrenergic control exerted in
    the lungs
  • All control occurs through circulating agents
    like epinephrine nor-epinephrine acting on
    alpha beta receptors located throughout the
    lungs

23
Locations of Receptors
  • Beta 2 receptors exist throughout all airways in
    the lung
  • Beta 1 Receptors are located primarily in the
    heart. There are some Beta 1 lung receptors
  • Alpha Receptors exist in the lung in lessor
    quantity than Beta Receptors
  • Have limited airway effects (some studies suggest
    stimulation of lung alpha receptors may actually
    cause bronchospasm).

24
Adrenergic Receptor Affect on Lung Blood Flow
  • Alpha 1 stimulation will cause vasoconstriction
    resulting in decrease in blood flow and an
    increase in blood pressure
  • Beta stimulation in the lung can cause
    relaxation of vessels causing vasodilation and
    increased blood flow

25
Cholinergic Lung Effects
  • Vagus nerve stimulation causes Muscarinic
    receptors (located mainly in larger airways) to
    induce bronchospasm
  • Receptors active in the lung are
  • M1
  • M2
  • M3 - responsible for causing bronchospasm

26
Other Sources of Nervous Control
  • Nonadrenergic Noncholinergic Inhibitory and
    Excitatory Nerves
  • Not well understood at this point
  • One possible neurotransmitter working in this
    system may be Nitric Oxide
  • Nitric Oxide administration causes vasodilation
    in the lungs

27
View of Airway Control Mechanisms
28
Adrenergic Bronchodilators
29
Specific Adrenergic Agents
  • Catecholamines
  • Resourcinals
  • Saligenins
  • Other non-catecholamines
  • Pirbuterol
  • Bitolterol (pro-drug)

30
Characteristics of Catecholamines
31
Characteristics of Non-Catecholamines
32
Drug Names Forms
33
Drug Names Forms Cont
34
Advantages of Inhalation
  • Quick Onset
  • Smaller doses are needed compared to p.o.
  • Fewer side effects
  • less Beta 1 fewer tremors
  • Direct dosing to airway
  • Safe and painless

35
Continuous Inhalational Dosing
  • Albuterol
  • 12 mg/hr (average dose)
  • 10 - 20 mg/hr (dose ranges)
  • Length 4 hours (average)
  • Length 1 - 10 hours (range of time)

36
Side Effects of Beta Agonists
  • Tremors
  • Tachycardia palpitations
  • Headache
  • Insomnia
  • Increase in BP
  • Nervousness
  • Nausea
  • Tachyphylaxis
  • Decrease in PaO2
  • Hypokalemia (only with continuous dosing)
  • Propellant induced bronchospasm
  • Sulfite Sensitivity

37
End of Week 4 - Thursday
Write a Comment
User Comments (0)
About PowerShow.com