Schizophrenia: Drug therapy: typical and atypical antipsychotics.

The idea

Antipsychotics dampen the dopamine system; they manage symptoms and do not cure. Typical drugs such as chlorpromazine, in use since the 1950s, are dopamine antagonists that block dopamine receptors in the synapse, and within days that reduces hallucinations and delusions. Chlorpromazine is also a powerful sedative acting on histamine receptors, which is why it calms a newly admitted patient. Atypicals act more widely: clozapine works on serotonin and glutamate too, so it lifts mood and is prescribed where a patient is suicidal, while risperidone binds more tightly and so works at lower doses with fewer side effects. Thornley's review found chlorpromazine beat placebo on symptom severity. The costs are real, from tardive dyskinesia to fatal neuroleptic malignant syndrome.

What earns the marks

• Antipsychotics are the main treatment, taken in the short term to calm an acute episode or in the long term to prevent relapse, and they reduce symptoms rather than cure the condition.
• Typical antipsychotics such as chlorpromazine are dopamine antagonists: they block dopamine receptors in the synapse, reducing dopamine action, which fits the original dopamine hypothesis and reduces positive symptoms.
• Chlorpromazine has a strong sedative effect through histamine receptors, so it is used to calm patients on admission, and dosage has fallen over time from the very high levels used in the past.
• Atypical antipsychotics such as clozapine also act on serotonin and glutamate receptors, which improves mood and reduces anxiety and depression, and clozapine is prescribed where a patient is at risk of suicide.
• Risperidone is a more recent atypical that binds more strongly to dopamine receptors, so it is effective in smaller doses and produces fewer side effects than typical drugs.
• Typical drugs carry serious side effects: weight gain, dizziness, sleepiness, and tardive dyskinesia, the involuntary facial movements caused by dopamine supersensitivity.
• Neuroleptic malignant syndrome is a rare but potentially fatal reaction causing high temperature, delirium and coma; clozapine can cause agranulocytosis, so patients need regular blood tests.

Common mistakes and how to put them right

• Saying antipsychotics cure schizophrenia.

  Put it right: They suppress symptoms while taken, and relapse is common when medication stops, which is why compliance is a central issue.

• Muddling the two types.

  Put it right: Typical drugs are dopamine antagonists with strong side effects; atypical drugs act on a wider range of receptors, with a better side-effect profile, and both block dopamine.

• Naming tardive dyskinesia without saying what it is. Marks come from describing involuntary movements of the face and tongue caused by dopamine supersensitivity, not from the term alone.

• Assuming effectiveness evidence is clean.

  Put it right: Healy pointed out that some trial data were published more than once, exaggerating the apparent evidence, and that the calming effect can be mistaken for a reduction in psychosis.

• Leaving out the ethical argument.

  Put it right: Antipsychotics used to make patients easier for staff to manage, the chemical-cosh criticism, raise a human-rights issue that is worth a full AO3 paragraph.

Exam tips

• Always link the drug back to the dopamine hypothesis; the mechanism mark is for explaining that blocking dopamine receptors reduces dopamine action, not for naming the drug.
• For evaluation, weigh effectiveness evidence against side effects and against the point that reducing dopamine only makes sense if the dopamine hypothesis is correct.
• In an application question, use the detail in the stem. A suicidal patient points to clozapine; a patient troubled by side effects points to risperidone or a lower dose.
• Name at least one specific typical and one specific atypical drug. An answer written entirely about "antipsychotics" cannot reach the top band.