Module 1.5.1 (Antipsychotics) Flashcards

1
Q

What does increase activity in mesolimbic pathway cause?

A

–Delusions – Hallucinations – Other +ve Sx of schizophrenia.

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2
Q

What does decrease activity in the mesocortical pathway cause?

A

– Apathy – Withdrawal – Lack of motivation & pleasure – Other –ve Sx of schizophrenia.

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3
Q

What does inhibition of the nigrostriatal pathway cause?

A

Causes extrapyramidal SE of antipsychotic drugs

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4
Q

What does inhibiton of the tuberoinfundibular pthway cause?

A

Elevated serum prolactin levels

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5
Q

How do most antipyschotic drugs work?

A

Most antipsychotic drugs block dopamine receptors

  • clinical dose is proportional to D2 receptor blockade

> Single positive electron tomography ligand scans show an increase in D2 receptors in nucleus accumbens of schizophrenia patients

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6
Q

Psychotic symptoms can be induced by drugs that increase dopaminergic activity. What drugs does this?

A

anti-parkinsonian agents

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7
Q

Drug-indcued parkinsonism is a common adverse effects of FGAs, it usually develops after weeks or months of treatment. What are these symptoms?

A
  • Stooped posture
  • Drooling
  • Back rigidity
  • Flexed elbows and wrists
  • Tremors in the legs
  • Slight flexed hip and knees
  • Shuffling gait
  • Reduced arm swing
  • Hand tremor

Bradykinesia (slow movements)

Akinesia (immobility) has also been reported

> Usually develops after weeks or months of treatment.

> Usually reversible with anticholinergics

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8
Q

What drugs mimic positive symptoms?

A
  • Amphetamine, methamphetamine (release dopamine & inhibit its reuptake) –> mimic positive symptoms
  • Psilocybin, LSD (5-HT2A agonists) mimic positive symptoms
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9
Q

What drugs mimic positive, negative and cognitive symptoms?

A

Phencyclidine, ketamine (glutamate NMDA receptor antagonists)

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10
Q

What are atypical antispychotics?

A

(Second Generation Antipsychotics)

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11
Q

What are positive symptoms of schizophrenia? Why does this happpen?

A

Agitation Delusions Disorganised speech Disorganised thinking Hallucination Insomnia

  • Due to excessive neuronal activity in mesolimbic neuronal pathway
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12
Q

What are negative symptoms of schizophrenia? Why does this happpen?

A

Apathy (avolition) Withdrawal Lack of motivation Lack of pleasure (anhedonia) Limited speech (alogia)

  • due to insufficient activity in mesocortical neuronal pathway
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13
Q

What MOA + drug is used to treat negative and cognitive symptoms that results from deficient cortical dopamine activity?

A

Respond to 5HT2A receptor antagonism produced by SGAs –> increase dopamine release

mesocortical pathway

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14
Q

What MOA + drug is used to treat positive symptoms that results from excessive subcortical dopamine activity?

A

Respond well to D2 receptor antagonism produced by FGAs & SGAs

mesolimbic pathway

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15
Q

5HT2A antagonists increase dopamine release in the mesocortical pathways but what effects do they have on D2 antagonists?

A

5HT2A antagonist enhance / complements action of D2 antagonist to reduce positive symptoms

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16
Q

What do neagative and cognitive symyptoms respond to?

A

respond to 5-HT2A receptor antagonism produced by SGAs

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17
Q

What do positive symptoms respond to?

A

Positive symptoms respond well to D2 receptor antagonism produced by FGAs & SGAs

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18
Q

Antipsychotics require 1-3 weeks to stabilise the positive symptoms of schizophrenia. What are the three-time dependent changes in dpamine neurotransmission?

A
  1. Immediate effects: An increase in dopamine synthesis, release, and metabolism but NO therapeutic effect
  2. 2Prolonged effects (1-3 weeks): Depolarization blockade –> reduced dopamine release from mesolimbic and nigrostriatal neurons –>alleviate the positive symptoms of schizophrenia while causing EPSE
  3. Extended prolong effects: Dopamine receptor up-regulation and supersensitivity to dopamine agonists –> may contribute to the development of a delayed type of EPS called tardive dyskinesia
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19
Q

What are examples of first gen antipsychotics (typical)?

clue: CDFHPZ

A
  • Chlorpromazine
  • Droperidol
  • Flupentixol
  • Haloperidol
  • Periciazine
  • Zuclopenthixol
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20
Q

What are examples of second gen antipsychotics (typical)?

A

Clozapine

Olanzapine

Quetiapine

Risperidone

Paliperidone

Amisulpride

Aripiprazole

Asenapine (Saphris wafer)

Ziprasidone (Zeldox®)

Lurasidone

Brexipiprazole (new drug)

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21
Q

What are some differences between FGAs and SGAs?

A

FGA only effective for positive symptoms

SGA can alleviate positive and negative symptoms

  • Incidence of extrapyramidal side-effects (less in the SGAs )
  • Efficacy in treatment-resistant groups of patients
  • Receptor selectivity
  • Pharmacological properties
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22
Q

What receptors does FGA have high affinity for?

A

High affinity for D2 receptors

> chlorpromazine, haloperidol, flupentixol

23
Q

What receptors does SGA have high affinity for?

A

high affinity for 5-HT2 receptors

> clozapine, risperidone, sertindole, quetiapine, aripiprazole

24
Q

What are pharmcokinetic considerations of antipsychotics?

A

Most antipsychotics have half-lives of 15-30h ™

Given orally or IM ™

Considerable individual variation ™

Dose needs to be individualised ™

Elderly requires reduction in dose ™

Depot formulation – long-term therapy

Fluphenazine decanoate – up to 28 days

ncreased risk of EPS with depot formulation

25
Q

What is responsible for antipsychotic action?

A

D2 receptor antagonism is essential for antipsychotic action

26
Q

How does SGA alleviate both positive and negative symptoms?

A

5HT2A antagonist

Negative symptoms: Inhibits 5HT2A receptors = increases dopamine release

Positive symptoms: HT2A antagonist enhance / complements action of D2 antagonist to reduce positive symptoms

27
Q

Howe does SGA protect against EPS in SGAs?

A

preserving nigrostriatal DA activity

> Also alleviate anxiety and insomnia in schizophrenia

28
Q

what does affinity for D2 receptors cause in FGA?

A

Affinity for D2 receptors cause of EPS (extrapyramidal sideeffects)

> FGAs are quite ineffective in treating negative & cognitive symptoms and EPS may become intolerable.

29
Q

Why are SGAs better than FGAs?

A
  • Alleviation of negative & cognitive symptoms as well as positive symptoms
  • Lower incidence of EPS and generally better tolerated
  • SGAs are superior to FGAs interact with 5-HT2A and D2 receptors
  • Antagonism of D3, D4 and other receptors may also contribute to the favourable clinical profile of SGAs
30
Q

What are the adverse effects of antipsychotics?

A
  • Adverse effects on Dopaminergic pathways

Psychological effects (mesolimbic/mesocortical)

Movement disorders (nigrostriatal)

Neuroendocrine (tuberoinfundibular)

> elevated prolactin

  • Blockade of a1 receptors –> Hypotension, reflex tachycardia
  • Blockade of histamine H1-receptor –> sedation and weight gain
  • Blockade of 5-HT2C & H1 receptors –> weight gain
  • Anti-cholinergic effects –> Blurred vision, dry mouth, constipation, urinary retention
  • Adverse effects due to immune reaction –> Hypersensitivity reactions, dermatitis, rashes, photosensitivity, urticaria
  • Adverse effects due to individual drug –> Clozapine cause agranulocytosis - neutropenia, bone marrow depression
  • Idiosyncratic reaction –> neuroleptic malignant syndrome
31
Q

What are acute EPS effects?

A
  • Acute neurological effects:

acute dystonia, akathisia, parkinsonism

  • Early EPS (within days)
  • Acute dystonias involuntary muscle spasms
  • Parkinsonian-like movements -tremor, rigidity & bradykinesia
32
Q

What is used to reverse parkinsonian like symptoms? What is the MOA?

A

Benztropine – anticholinergic – block muscarinic receptors that mediate striatal cholinergic excitation – reduce the excessive cholinergic activity due to D2 blockade by FGAs

33
Q

What is acute dystonia? What does it include?

A

Muscle spasm of face, tongue, neck, jaw and/ or hands

Hyperextension of neck & trunk & arching of back.

Can interfere with walking, talking or swallowing

Inlcudes

  • Torticollis
  • Carpopedal spasm
  • Trismus (lock-jaw)
  • Perioral spasm
  • Oculogyric crisis
34
Q

What is akathisia (acute eps)? When does it happen?

A
  • Motor restlessness ™
  • Person unable to sit or stand still, feels urgent need to move, pace, rock or tap foot ™
  • Can also present as apprehension, irritability & general uneasiness ™
  • Often confused with worsening agitation* ™
  • More common in females

Usually occurs 2-3 days (up to several weeks) after starting Tx & may subside spontaneously.

35
Q

What are some chronic EPS effects?

A

Chronic neurological effects: Tardive dyskinesia, Tardive dystonia

Tardive dyskinesia

  • Characterised by abnormal involuntary movements of the mouth, face, tongue and sometimes head, neck, trunk or limbs
  • Best approach is prevention / Use SGAs rather than FGAs
36
Q

Why does Tardive dyskinesia occur? How long does it take to occur?

A

May be due to a delayed adaptive proliferation of nigrostriatal D2 receptors or neurodegeneration resulting from excessive glutamate release due to chronic antagonism of inhibitory D2 receptors

  • usually after 6-24 months of chronic FGA treatment
37
Q

What are symptoms of neuroleptic malignant snydrome? Which patients does it occur in?

> caused by antipsychotics

A
  • Symptoms include fever, extrapyramidal motor disturbances, muscle rigidity and COMA

Rare but potentially fatal adverse event occurring in patients extremely sensitive to EPS (muscle rigidity & hyperthermia)

38
Q

what treatment for neuroleptic malignant snydrome?

A

URGENT treatment required –dantrolene (direct-acting skeletal muscle relaxant) and bromocriptine (dopamine agonist)

39
Q

What is mnemnic for neuroleptic malginant syndrome features?

A

FEVER

F - Fever • E - Encephalopathy • V - Vitals unstable • E - Elevated enzymes (elevated CPK) • R - Rigidity of muscles

40
Q

What are the major drug interactions for the following FGA:

A) Chlorpromazine

B) Fluphenazine

C) Haloperidol

A

A)

  • Additive effects with antiadrenergic, anticholinergic, and CNS depressants.
  • Decreases serum levels of lithium
  • Concurrent use of a β-adrenergic receptor antagonist or an antidepressant may increase serum levels of both drugs

B)

  • Additive effects with anticholinergic and CNS depressants
  • Concurrent use of a β-adrenergic receptor antagonist (beta blocker) or an antidepressant may increase serum levels of both drugs

C)

  • Barbiturates and carbamazepine decrease serum levels
  • Quinidine increases serum levels
41
Q

What are the major drug interactions for the SGA:

A) clozapine

B) olanzapine

C) risperidone

A

A)

Not established; possible interaction with drugs that induce or inhibit cytochrome P450 isozyme CYP1A2.

B)

same as clozapine

C)

Not established; possible interaction with drugs that induce or inhibit cytochrome P450 isozyme CYP2D6.

42
Q

What are precautions for antispyhcotic drugs?

A

Parkinson’s disease •

Epilepsy •

Respiratory failure •

Hyperthyroidism •

Shock •

Risk factors for prolonged QT interval •

GI obstruction, urinary retention, myasthenia gravis –> anticholinergic effects exacerbate this

Low WCC or previous blood dyscrasia •

Diabetes –> olanzapine, clozapine, quietapine increases BSL

Elderly –> Associated with increased risk of stroke & death

43
Q

D2 receptors blockade lead to increased prolactin release, what are the effects of this?

A

Galactorrhoea Amenorrhoea Gynaemastia Infertility

44
Q

Pharmacalogy of chlorpromazine (fga)

A

EPS can become troublesome

Prominent sedation, hypotension & antimuscarinic effects /

Can cause obstructive jaundice and photosensitivity leading to sunburn

Useful when sedation is desired

Administered orally, IV or IM

45
Q

Pharmacology of haloperidol (fga)

A

“high potency antipsychotic” /

EPS is a main problem /

Favoured when sedation, hypotension, and antimuscarinic effects are undesirable (elderly patients)

Administered orally or IM

46
Q

pharmacology of flupentixol decanoate (FGA)

A

“depot preparation” that can be administered IM every 2-4 weeks /

Minimal sedation & hypotension, but prominent EPS

47
Q

When should long acting depot antipsychotics such as Flupenthixol decanoate, haloperidol decanoate, risperidone be used?

A

Should be considered for schizophrenic patients who do not reliably take oral antipsychotic medication

48
Q

What are the clinical used of FGAs?

A

Treatment of acute and chronic psychoses ›

Treatment of acute mania ›

Management of “organic psychoses”, such as those seen in elderly patients with dementia and dementia-associated agitation (progressive failure of intellectual and cognitive function.) ›

Severe behavioural disorders on children ›

Adjunct in psychotic depression ›

Adjunct in anaesthesia ›

Adjunct in treatment of alcoholic hallucinosis ›

Treatment of Gilles de la Tourette and other choreas ›

Acute treatment of intractable nausea and vomiting (haloperidol, droperidol). ›

Treatment of intractable hiccough (chlorpromazine).

49
Q

Pharmacology of clozapine

A

Highly effective for treating the positive, negative & cognitive symptoms of schizophrenia without producing EPS

Reduces the suicide rate /

Risk of agranulocytosis (1% of patients). Regular monitoring of blood required if prescribed. /

Convulsions can occur /

Other side-effects include: prominent sedation, weight gain, impaired glucose regulation, hypotension and antimuscarinic effects

> Use clozapine in schizophrenics unresponsive to other antipsychotics

50
Q

Pharmacology of olanzapine

A

Has a similar therapeutic profile to clozapine. However, it may not be as effective as clozapine in severely impaired schizophrenics.

Does not cause agranulocytosis

Convulsions can occur

Side-effects include: sedation, weight gain, impaired glucose regulation, hypotension and antimuscarinic effects

Olanzapine is a widely prescribed antipsychotic for schizophrenia and other psychoses

51
Q

Pharmacology of risperidone

A

Effective for treating positive, negative & cognitive symptoms of schizophrenia.

Above usual therapeutic doses (!4-6 mg/day), it can produce EPS

Does not cause agranulocytosis

Antimuscarinic effects are minimal /

Side-effects include: mild sedation, mild weight gain & impaired glucose regulation, hypotension, hyperprolactinaemia

Risperidone is a widely prescribed antipsychotic for schizophrenia and other psychoses

52
Q

Pharmacology of Quetiapine

A

Can treat positive, negative & cognitive symptoms without producing EPS

Does not cause agranulocytosis

Side-effects include sedation, dry mouth, constipation, hypotension, mild weight gain & impaired glucose regulation

Quetiapine is a useful antipsychotic for treating schizophrenia

53
Q

Pharmacology of aripiprazole

A

Improve positive symptoms and reduce relapse rates after an acute episode.

Does not cause agranulocytosis

Side-effects include: sedation, weight gain, impaired glucose regulation, hypotension and antimuscarinic effects

precautions

Recent history of MI, unstable heart

Treatment with CYP3A4

Poor metaboliser - CYP2D6

Indicated for schizophrenia and bipolar disorder as monotherapy

54
Q

What are the clinical used of atypical antipsychotic drugs?

A

Treatment of acute and chronic psychoses (e.g. schizophrenia)

Acute mania (olanzapine, quetiapine, risperidone)

Organic psychoses (e.g. dementiaassociated agitation)

Severe behavioural disorders in children