CNS 2

• CNS Stimulants


  • Cortical stimulants
  • Medullary stimulants
  • Spinal stimulants

  
• CNS Depressants


  • Sedatives
  • Tranquilizers
  • Centrally acting muscle relaxants
  • Analgesics
  • Antipyretics
  • Neuroleptanalgesia
• Specific drugs acting on the CNS

  Modify some steps in chemical synaptic transmission of nerve impulse

  
• Non-specific drugs acting on the CNS

  Affect many targets by diverse or poorly understood mechanisms

  
• Excitatory neurotransmitters


  • Glutamate
  • Acetylcholine
  • Noradrenaline
• Inhibitory neurotransmitters


  • GABA
  • Glycine
  • Serotonin
  • Dopamine
  • Acetylcholine
  • Noradrenaline
• CNS stimulants


  Drugs which increase the muscular (motor) and the mental (sensory) activities
• Effects of CNS stimulants

  • Increase in alertness and wakefulness
  • Increase in nervousness and anxiety
  • Convulsions
• Categories of CNS stimulants

  • Convulsants and respiratory (Medullary) stimulants
  • Psychomotor stimulants
  • Psychotomimetic drugs (Hallucinogens)

  
• Respiratory stimulants


  • Doxapram
• Spinal cord stimulants


  Increase reflex excitability of the spinal cord
• Spinal cord stimulants


  • Strychnine
  • Bicuculline
• Medullary stimulants


  • Picrotoxin
  • Pentylenetetrazol
• Psychomotor stimulants (Cerebral cortex stimulants)


  Have a marked effect on mental function and behaviour, produce excitement and euphoria, reduced sensation of fatigue, and increase in motor activity
• Psychomotor stimulants


  • Picrotoxin
  • Amphetamine and related compounds
  • Cocaine
  • Methylxanthines (e.g. caffeine, theophylline)
• Psychotomimetic drugs (Hallucinogens)


  Mainly affect thought patterns and perception, distorting cognition in a complex way, producing effects that superficially resemble psychotic illness
• Doxapram


  Short-acting respiratory stimulant sometimes given by intravenous infusion to treat acute respiratory failure
• Strychnine


  Antagonist of glycine, main action is to increase reflex excitability of spinal cord, used as aphrodisiac, general tonic, neuromuscular purgative, ruminal tonic, and motor activator for race horses
• Mechanism of action of methylxanthines

  1. Inhibit phosphodiesterase enzyme, increasing cAMP

  2. Antagonize adenosine (A1, A2 and A3) receptors, responsible for CNS stimulation and smooth muscle relaxation
• Cocaine


  Blocks reuptake of monoamines (NE, serotonin and dopamine), producing intense euphoria and powerful stimulation of cortex and brain stem, also has local anesthetic action
• Hallucinogens (psychotomimetic drugs)


  Affect thought, perception, and mood, producing profound changes in thought patterns and mood, with little effect on the brain stem and spinal cord
• General anesthesia


  Reversible loss of consciousness induced by inhibiting neuronal impulses in several areas of the central nervous system, producing analgesia, amnesia, and unconsciousness
• Local anesthesia


  Briefly disrupts sensory nerve impulse transmission from a specific body area or region, including topical anesthesia and local infiltration
• Purposes of anesthesia include producing muscle relaxation, analgesia, artificial sleep or loss of consciousness, blocking nerve impulse transmission, and suppressing reflexes