CNS drugs

CNS drugs

Disorders
1. Depression 5HT NA low levels
  1. SSRIs MOA: selectively bind to reuptake pump and inhibit the reuptake of 5HT. ADE less than other antidepressants, nausea, nervousness, insomnia, sexual dysfunction, serotonin syndrome
    1. Fluoxetine (Prozac) T1/2 16 days
    2. Paroxetine (Aropax)
    3. Citalopram
    4. Setraline(Zoloft)
  2. MAOIs MOA: Bind to MAO a and b enzymes and inhibit it which stops the catabolism of NA allowing it to be stored. Ireversible.Increases adrenaline and noradrenaline in the CNS and peripheries ADE SNS Anticholinergic. Risk of hypertensive crisis with tyramine
    1. Phenelzine
    2. tranylcypromine
  3. RIMAs MOA: Selectively Binds to MAOa enzyme and inhibit its action which stops the catabolism of NA. Reversible.Less AVE.
    1. Moclobemide
  4. TCAs MOA: Bind to reuptake pump and block it inhibiting the reuptake of NA and 5HT allowing them to remain in the synaptic cleft for longer. they also block histamine receptors, M receptors and a1 receptors leading to AVE anticholinergic, sedation H, weight gain, postural hypotension. OD cardiac arrythmia
    1. Amitriptyline
    2. Doxepine
    3. Norptiptyline
    4. Dothiepin
    5. Clomipramine
2. Bipolar
  1. Mood Stabilisers
    1. lithium(lithicarb): MOA= thought to enhance action of reuptake pump and inhibits NA release. Narrow therapeutic index.Inverse relationship with Na+ helps with mania and depression as tx and prophylaxis
    2. Sodium valproate (Epilim)
  2. Carbamazepine(tegretol)
  3. lamotrigine
3. Schizophrenia :chemical imbalance too much DA positive symptoms=delusions of thought ,disorders of perceptions, halucinations. Neg bluntness, apathy, social withdrawl
  1. Antipsychotics MOA: Block DA transmission in specific areas of the brain especially D2 (Limbic)receptors.DA receptor antagonists.
    1. Typical antipsychotics: more likely to reduce positive symptoms
      1. Phenothiazines
        chlorpromazine(Largactil)
      2. Thioxanthines
        Zuclopenthixol
        flupenthixol
      3. Butyrophenones
        Haloperidol
        Pimozide
      4. Extrapyramidal adverse effects= ADOPT Akathisia, Dystonia, Oculogyric crisis, Parkinsonism, tardive dyskinesia
        Akathisia=restlessness and rigidity
        Dystonia: torticollis, wry neck, muscle spasms
        oculogyric crisis= upward rolling of eyes
        parkinsonism: fine tremor, bradykinesia, rigidity, shuffling gait, drooling
    2. Atypical antipsychotics: more likely to reduce negative symptoms AVE Extrapyramida, anticholinergic,sedation (antihistaminic), endocrine effects, postural hypotension(blockage of a1receptors),neuroleptic malignant syndrome
      1. Olanzapine
      2. Clozapine: risk of T2DM, dyslipidaemia, Agranulocytosis
        Clozapine OD symptoms: drowsiness, delirium ,coma, hypotension,tachycardia, arrhythmias, bronchoconstriction, potentially fatal.
      3. Risperidone
      4. Quetiapine
  2. Psychoses
  3. neuroses
Monotherapy is best
Serotonin syndrome occurs when 5HT levels are too high which happens when 2 or more antidepressants are used together pethedine, tramadol, MAOIs, RIMAS, TCAs, LSD, Symptoms inc agitation restlessness, confusion, hyperthermia, tachycardia, ataxia, sweating
Tetracyclic Antidepressants block a2 receptors
1. maprotiline
2. mianserin
Selective Noradrenaline reutake inhibitors (SNRIs)
1. roboxetine
Selective 5HT NA reuptake inhibitors
1. venlafaxine
St John's wart
DA pathways in the brain
1. Mesolimbic: hyperactivity leads to emotional disorders
2. Mesocortical: Low levelsof DA = negative symptoms
3. Nigrostratial: low levels motor movements/ extrapyramidal system
4. Tuberoinfundibular: DA inhibits prolactin release
Anxiolytics
1. Benzodiazepines: potentiate the inhibitory actions of GABA. hyperpolarizes the neuron making it harder to generate action potential Drug interactions= other CNS depressants, drugs that affect microsomal enzyme met
  1. Diazepam

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	Created by Carly Doolan over 10 years ago