Drugs acting on the CNSI

1. 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: • 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: • Anxiety: • 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: • Anxiety disorders • (Muscular disorders • Seizures • Sleep disorders • Pharmacokinetics: • Absorption and distribution: • Lipophilic • Rapidly absorbed

7. Benzodiazapine • Pharmacokinetics: • Duration of action: • 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: • Drowsiness and confusion. • Precautions: • 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: • Anesthesia • Anticonvulsant • Anxiety • Pharmacokinetics: • Metabolized by the liver • Distributed to: • Splanchnic area • Skeletal muscles • Adipose tissue

11. Barbiturate • Adverse effects: • CNS: • 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. WelcomeBuspirone • 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: • depression: • 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. 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