SCHIZOPHRENIA: MOM - Antipsychotic Drugs Flashcards
Schizophrenia: Antipsychotic Drugs - A01 Intro
Before using the first antipsychotic medication, schizophrenia had been unsuccessfully treated with various regimens.
- Trepanning: Holes were drilled into the heads to release evil spirits
- Whirling: Patient was put into a coma and revived quickly
There are numerous types of antipsychotic medication though most are likely to fall into either the conventional or atypical antipsychotic:
Schizophrenia: Antipsychotic Drugs - A01 Titles
Conventional Antipsychotics
- Chlorpromazine
Atypical Antipsychotics
- Clozapine
Differences
Dosage
Schizophrenia: Antipsychotic Drugs A01 Conventional Antipsychotics - Definition
Known as ‘typical’ / ‘older’ / ‘first generation’ antipsychotics
E.g. Chlorpromazine
- Developed in 1950s
Work by affecting neurotransmitters, specifically blocking the dopamine neurotransmitter
- Chlorpromazine acts primarily as an antagonist (blocking D2 receptors)
- Also blocks other dopamine receptor subsites (D1 / D3 / D4 / D5)
Schizophrenia: Antipsychotic Drugs A01 Conventional Antipsychotics - How they work
- After presynaptic neuron releases dopamine into the synapse, the receptor sites on the postsynaptic neuron are blocked by chlorpromazine
- Reduces the activity in the postsynaptic neuron
- Initially causes the presynaptic neuron to increase its dopamine production / meaning a rise in dopamine secretion
- In due course, the production of dopamine drops because it is depleted and the amount of dopamine in the synapse decreases
- Lower levels of dopamine in the synapse in addition to the enduring blockade leads to a substantial decrease in neural activity
- Reduction of dopamine in the mesolimbic pathway is thought to be responsible for the decline of positive symptoms
- Chlorpromazine is also seen to affect the serotonin receptors as well as other sites in the brain but it is mainly a dopamine antagonist
Schizophrenia: Antipsychotic Drugs A01 Atypical Antipsychotics
E.g. Clozapine
Atypical antipsychotics are known as the ‘newer’ or ‘second generation’ antipsychotics
- Developed since the 1900s
- Work by acting as a dopamine antagonist
- Precise mechanisms of atypical antipsychotics are not yet clear
Schizophrenia: Antipsychotic Drugs A01 Differences - Definition
Some report that atypical antipsychotics are different from conventional antipsychotics because:
- They are received at fewer dopamine D2 receptor sites and more D1 and D4 receptor sites
- Most atypical antipsychotics also antagonise to the same degree as the dopamine receptors
- (bind to receptor - blocking its usual function) the serotonin receptors
SEEMAN: ‘Fast-off’ theory
Schizophrenia: Antipsychotic Drugs A01 Differences - Seeman
‘fast-off’ theory: proposes that atypical antipsychotics bind more loosely to D2 receptor sites than conventional
- Although the blockade has a therapeutic effect; it does not last long enough to produce the side effects conventional antipsychotics do
Schizophrenia: Antipsychotic Drugs A01 Dosage: Chlorpromazine
(largactil) can be prescribed as a tablet, oral solution, intramuscular injection, or suppository
- 1,000mg (1g) is the highest daily dose
- Maximum dose ranges from 40-75mg for children (depending on age)
Schizophrenia: Antipsychotic Drugs A01 Dosage: Clozapine
(clozaril / denzapine / zaponex) are usually prescribed in tablet form
- 900mg - maximum daily dose
- Patients, prescribing physician & dispensing pharmacist must be registered with a specialised monitoring service
- Drug carries a 3% risk of causing agranulocytosis (potentially fatal drop in white blood cells)
- Regular blood checks necessary - weekly, then fortnightly
- Drug carries a 3% risk of causing agranulocytosis (potentially fatal drop in white blood cells)
Schizophrenia: Antipsychotic Drugs A03 - Evaluative Points
EFFECTIVENESS: Conventional Antipsychotics / Difficulty Assessing the Effectiveness of Antipsychotics
ETHICAL: Side Effects
SOCIAL: Risk of Violence
Schizophrenia: Antipsychotic Drugs A03 - Effectiveness: Conventional Antipsychotics
Cole et al. - Psychiatry could treat mental disorders the same way physical disorders are treated
- 75% given conventional antipsychotic = considered to be much improved
- 25% given placebo = considered to be much improved
Schizophrenia: Antipsychotic Drugs A03 - Effectiveness: Difficulty Assessing the Effectiveness of Antipsychotics
NON-COMPLIANCE:
Particular issue with chronic schizophrenics - they tend to lack the necessary ‘insight’ into their condition (don’t believe they have a problem and therefore don’t take the medication)
Schizophrenia: Antipsychotic Drugs A03 - Ethical
SIDE EFFECTS:
Psychiatrists have to determine whether the benefits of taking medication is worth the potential side effects for each patient
- When schizophrenics are first diagnosed / experiencing an acute episode of the disorder, medication may be given without valid consent
- Side effects are not of their choosing
- Severe potential side effects:
- Tardive dyskinesia: uncontrollable, sudden, irregular movements in the face / body
- Parkinsonism: tremors / instability
- Seizures
Schizophrenia: Antipsychotic Drugs A03 Social
RISK OF VIOLENCE
A serious consequence of schizophrenics not following their drug therapy is that they may pose a threat to themselves or others
NCISH - 346 homicides committed in Britain were committed by those with a history of schizophrenia
- 29% of these had been non-adherent with their drug therapy in the last month
RISK FACTOR ONLY!!!
