1. Drugs acting on the CNSI
Unit 8
Week 5
Dr.Mohammed Hassan
Drugs acting on the CNSI
Al-Hamadi , Drugs acting on the CNSI. 4medstudents.com 2003

2. Drugs acting on the CNS 1
The psychotic disorders are classified into 3 major groups:
Anxiety disorders (phobia and sleeping disorders).
Effective/mood disorders (depression)
Personality disorders (Schizophrenia)

3. Drugs acting on the CNS 1 Anxiolytic Drugs: Antidepressant Drugs:
Benzodiazepines(BDZ)
Barbiturate.
Buspirone
Antidepressant Drugs:
Tricyclic/Plycyclic
Monoamine oxidase inhibitors
Selective serotonin-reuptake inhibitors (SSRI)
Neurolytic Drugs:
Phenothiazin
Buteopheanol

4. Anxiety and Anxiolytic Drugs:
Definition:
Unpleasant state of tension or a fear that seems to arise from an unknown source.
Symptoms:
Tachycardia
Sweating
Palpitations
Sympathetic activation

5. Anxiolytic Drugs (Benzodiazapine)
Diazepam,Lurazepam, Midazolam
Mode of action:
Binding of GABA to its receptor trigger an opening of chloride conductance. The influx of chloride ions causes hyperpolarization that moves the post synaptic potential away from its firing threshold and thus inhibits the formation of action potential and neural firing>
Actions:
Reduction of anxiety( at low doses)
Sedative and hypotonic actions (at higher doses)
Anticonvulsant
Muscle relaxant

6. Benzodiazapine Therapeutic uses: Pharmacokinetics: Anxiety disorders
(Muscular disorders
Seizures
Sleep disorders
Pharmacokinetics:
Absorption and distribution:
Lipophilic
Rapidly absorbed

7. Benzodiazapine Pharmacokinetics: Dependence: Duration of action: Fate:
Short, intermediate and long acting.
Fate:
Metabolized by the hepatic microsomal metabolism system.
Dependence:
At high doses
Results in withdrawal symptoms:
Confusion, anxiety, restlessness and tension.

8. Benzodiazapine Adverse effects: Precautions: Drowsiness and confusion.
Cautiously in treating patients with liver disease.
Goodbye BDZ

9. Welcome (Barbiturate)
Phenobarbiturate, amobarbiturate
Mode of action:
Interfere with sodium and potassium transport across cell membranes.
Actions:
Depression of CNS (at low doses)
Hypnosis and anesthesia ( at high doses)
Respiratory depression.
Enzyme induction (P-450 microsomal enzyme in liver)

10. Barbiturate Therapeutic uses: Pharmacokinetics: Anesthesia
Anticonvulsant
Anxiety
Pharmacokinetics:
Metabolized by the liver
Distributed to:
Splanchnic area
Skeletal muscles
Adipose tissue

11. Barbiturate Adverse effects: CNS: Drug hangover Addiction: Poisoning:
Drowsiness, impaired concentration and mental sluggishness
Drug hangover
Tiredness, nausea and dizziness
Addiction:
Tremor, anxiety, tiredness, restlessness, nausea and vomiting
Poisoning:
death
Goodbye Barbiturate

12. Goodbye all Anxiolytic Drugs
Welcome Buspirone
Useful in the treatment of generalized anxiety disorders.
Action:
The action is mediated by serotonin receptors.
Adverse effects:
Dizziness
Nervousness
ligthheadness
The action is mediated by serotonin receptors
Goodbye all Anxiolytic Drugs

13. Depression and Antidepressant drugs:
Definition:
Pervasive mood altering illness affecting energy, sleep, appetite and the ability to function.
Symptoms:
Depression
Sadness
Hopelessness
Inability to experience pleasure in usual activity

14. Antidepressant Drugs (Tricyclic/Polycyclic)
Amitriptyline, Imipramine
Mode of action:
Inhibit the neuronal reuptake of norepinephrine and serotonin into presynaptic nerve terminals which leads to increased concentration of monoamine in the synaptic clef.
Blocking serotonergic,a-adrenergic, histamine and muscurinic receptors.
Actions:
Elevate moods
Improve mental alertness
Increase physical activity

15. Tricyclic/Polycyclic
Therapeutic uses:
Depression
Panic disorder
Bed-wetting in children
Pharmacokinetics:
Absorption and distribution:
Lipophilic
Low bioavailability
Metabolized by hepatic microsomal system

16. Tricyclic/Polycyclic antidepressant
Adverse effects:
Anti muscarinic effects:
Blurred vision, dry mouth, urinary retention and constipation
Increase cardiovascular stimulation
Sedation
Orthostatic hypotension:
By blocking a-adrenergic receptors.
Goodbye tricyclic/polycyclic

17. Welcome (monoamine oxidase inhibitors)
Hydralazine, phenelzine
Mode of action:
Reverrsibly or irreversibly inactivate the enzyme, this result in increased norepinephrine, serotonin and dopamine with in the neuron.

18. monoamine oxidase inhibitors
Therapeutic uses:
Depression
Phobic states
Pharmacokinetics:
Effect require 2 to 4 weeks

19. monoamine oxidase inhibitors
Adverse effects:
Inability to degraded tyramine obtained from the gut
Cheese
Chicken liver
Tyramine causes the release of large amounts of stored catecholamines from verve terminals resulting in:
Headache
Tachycardia
Nausea
hypertension
Goodbye MAO Inhibitors

20. Welcome (Selective Serotonin-Reuptake Inhibitors)
Fluoxetine
Actions:
Inhibit serotonin reuptake ( selective for serotonin)
Therapeutic uses:
Depression
Panic disorders
Pre menstrual syndrome

21. Selective Serotonin-Reuptake Inhibitors
Pharmacokinetics:
Slowly cleared from the body
Potent inhibitor of a hepatic cytochrome P-450.
Adverse effects:
Nausea
Anxiety
Insomnia
Sexual dysfunction
Weight loss
tremors
Goodbye SSRI

22. Personality disorders and antipsycotic (neuroleptic) Drugs:
schizophrenia
Definition:
Mental disorder caused by some inherited dysfunction of the brain.
Symptoms:
Delusions
Hallucination
Thinking or speech disturbance

23. (neuroleptic drugs)
Five important classes. Most important classes are:
Phenothiazines
Fluphenazine
Promethazine
Butyrophenones
Haloperidol
Doroperidol
Mode of action:
Block dopamine and serotonin receptor in the brain
Many of these drugs also block cholinergic, adrenergic and histamine receptors

24. neuroleptic drugs Actions: Antipsychotic actions:
Reduce hallucinations by blocking dopamine receptors.
Extrapyramidal effects:
Parkinson syndrome by blocking the dopamine receptors in the nigrostriatal pathway.
Antiemetic effects:
By blocking dopaminergic receptors.
Antimuscarinic effects:
Blurred vision, dry mouth, sedation and confusion.
Other effects:
Hypotension and lightheadedness by blocking a-adrenergic receptors

25. Goodbye Neuroleptic Drugs
Therapeutic uses:
Schizophrenia
Prevention of severe nausea
Treatment of severe pain
Adverse effects:
Tremors
Postural hypotension
Constipation
Urinary retention
Confusion
Sexual dysfunction
Goodbye Neuroleptic Drugs

26. Thank You Team