Drugs for the ANS Autonomic Nervous System

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Drugs for the ANSAutonomic Nervous System

• Chapter 7

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Introduction

• Neuropharmacology represents one of the largest,
  most complicated, and least understood branches
  of pharmacology.
• Nervous system medications are used to treat a
  large and diverse set of conditions, including
  pain, anxiety, depression, schizophrenia,
  insomnia, and convulsions.

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Introduction

• Through their effects on nerves, medications are
  also used to treat many disorders that are
  considered diseases of other organ systems.
• Examples include abnormalities in heart rate and
  rhythm, high and low BP, pressure within the
  eyeball, asthma, and even a runny nose.

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Peripheral Nervous System

• The peripheral nervous system is divided into
  somatic and autonomic components
• Nervous systemtwo major divisions
• 1. Central nervous system (CNS)brain and spinal
  cord.
• 2. Peripheral nervous system (PNS)nervous
  tissue outside the CNS

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Nervous System

• Basic Functions of the nervous system
• Recognize changes in the internal and external
  environments
• Process and integrate the environmental changes
  that are perceived
• React to the environmental changes by producing
  an action or response

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Peripheral Nervous System

• Peripheral nervous system
• Sensory and motor functions
• Somatic nervous systemcontrol skeletal muscles
  (voluntary)
• Autonomic nervous systemcontrols smooth muscle,
  cardiac muscle and glands (involuntary)

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Autonomic Nervous System

• The autonomic Nervous system has sympathetic and
  parasympathetic branches.
• Most organs and glands have nerves from both
  branches.

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Autonomic Nervous System

• Sympathetic Nervous system
• Functionactivated under conditions of stress
• Fight-or-flight--
• Parasympathetic nervous system
• Functionactivated under non-stressful conditions
  
• Rest and relax

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Autonomic Drugs

• Autonomic drugs classified by which receptors
  they stimulate or block
• Sympathomimetics or adrenergic agonists stimulate
  sympathetic nervous systemproduce the classic
  symptoms of the fight-or-flight response.
• Parasympathomimetics or cholinergic agonist
  stimulate parasympathetic nervous system and
  produce the classic symptoms of the
  rest-and-relaxation response.

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Autonomic Drugs

• Adrenergic blockers inhibit sympathetic nervous
  division which is the opposite action of
  sympathomimetics.
• Anticholinergic or cholinergic blockers inhibit
  parasympathetic nervous system which is the
  opposite action of parasympathomimetics

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Parasympathomimetics

• Table 7.3 pg. 92.
• Few therapeutic uses because of numerous side
  effects.
• Include organic phosphate insecticides and toxic
  nerve gases
• Some useful for effects on acetylcholine receptor
  in skeletal muscles and CNS.
• Drug profilel (Urecholine) pg. 93
• Helps in Urination

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Anticholinergics

• Table 7.4 pg. 95
• Also called Muscarinic blockers.
• Most therapeutic uses of the anticholinergics are
  predictable extension of their autonomic actions
  dilation of the pupil, increase in heart rate,
  drying of secretions, and dilation of the
  bronchi.

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Anticholinergics

• Many side effectstachycardia and urinary
  retention.
• Replaced with safer and more effective drugs
• Some used for effects on CNS
• Scopolamine (Hyoscine)sedation and motion
  sickness
• Benztropine (Cogentin)Parkinsons disease
• Drug profileatropine pg. 95

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Sympathomimetics

• Table 7.5 pg. 98.
• Stimulate alpha an/or beta receptors
• Selectivestimulate only one type of adrenergic
  receptor
• 1. Alpha 1nasal mucous membrane decrease
  secretions phenylphrine (neo-Synephrine)

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Sympathomimetics

• 2. Alpha 1blood vessels relax smooth muscle
  clonidine (Catapress)
• 3. Beta 1heart increase heart rate and force
  of contraction dobutamine (Dobutrex)
• 4. Beta 2airways relax smooth muscle
  albuteron (proventil)

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Sympathomimetics

• NonselectiveStimulate more than one adrenergic
  receptor
• All 4 types of adrenergic receptorsheart and
  airwaysepinephrine
• Alpha 1 and beta2nasal mucous membrane and
  heart pseudephrine (Sudafed)
• Beta 1 and beta 2heart and airways
  isoproterenol (Isuprel)

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Adrenergic Blockers

• Most widely prescribed autonomic drugs for
  hypertension.
• They may be selective for only one receptor
  subtype, such as the beta1-blockers,or inhibit
  several subtypes.
• HTN is their primary indication.