Presentation on theme: "Drugs acting on the CNSI Unit 8 Week 5 Dr.Mohammed Hassan Al-Hamadi, Drugs acting on the CNSI. 4medstudents.com 2003."— Presentation transcript:
Drugs acting on the CNSI Unit 8 Week 5 Dr.Mohammed Hassan Al-Hamadi, Drugs acting on the CNSI. 4medstudents.com 2003
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)
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
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 Anxiolytic Drugs (Benzodiazapine)
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.
Benzodiazapine Adverse effects: Drowsiness and confusion. Precautions: Cautiously in treating patients with liver disease.
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) Welcome (Barbiturate)
Barbiturate Therapeutic uses: Anesthesia Anticonvulsant Anxiety Pharmacokinetics: Metabolized by the liver Distributed to: Splanchnic area Skeletal muscles Adipose tissue
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
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
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
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 Antidepressant Drugs (Tricyclic/Polycyclic)
Tricyclic/Polycyclic Therapeutic uses: Depression Panic disorder Bed-wetting in children Pharmacokinetics: Absorption and distribution: Lipophilic Low bioavailability Metabolized by hepatic microsomal system
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.
Hydralazine, phenelzine Mode of action: Reverrsibly or irreversibly inactivate the enzyme, this result in increased norepinephrine, serotonin and dopamine with in the neuron. Welcome (monoamine oxidase inhibitors)
monoamine oxidase inhibitors Therapeutic uses: Depression Phobic states Pharmacokinetics: Effect require 2 to 4 weeks
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
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
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
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 (neuroleptic drugs)
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
neuroleptic drugs Therapeutic uses: Schizophrenia Prevention of severe nausea Treatment of severe pain Adverse effects: Tremors Postural hypotension Constipation Urinary retention Confusion Sexual dysfunction