Antipsychotics and bipolar disorder

How do they work?

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Antipsychotic medicines are sometimes used together with mood stabilisers to help treat an episode of high mood (mania).

They are used as an initial treatment to help control the symptoms while the mood stabiliser begins to work.

Antipsychotic medicines can also treat mania with psychotic symptoms such as hallucinations, delusions or hearing voices.

The antipsychotic is usually stopped once the symptoms are under control, and treatment is continued with mood stabilisers.

However, some antipsychotics may also stabilise mood, and these medicines have a role as maintenance treatments to prevent episodes of ill health.

There are two types of antipsychotic medicine:

  • typical antipsychotics
  • atypical antipsychotics.

    How do they work?

    Antipsychotics are sometimes described as 'major tranquillisers', but this term is fairly misleading, as this type of medicine is not just a tranquilliser, and any tranquillising effect is not as important as the main way they work in psychiatric illness.

    Antipsychotic medicines work by affecting the activity of chemicals called neurotransmitters that are found in the brain. In particular, they decrease the activity of dopamine, a neurotransmitter that is involved in controlling mood and behaviour.

    Levels of dopamine have been shown to be raised in the brains of people going through a manic episode, and blocking the activity of this dopamine is thought to be the main way in which antipsychotic medicines work to control manic symptoms.

    How long do they take to work?

    Antipsychotics work very quickly to control manic behaviour, particularly if they are given by injection.

    Once the manic episode is controlled, the length of time the antipsychotic is continued for depends on individual circumstances, including whether the medicine will be continued long-term as a mood stabiliser. In any case, treatment should not usually be stopped abruptly as this could cause the manic symptoms to come back, or on rare occasions, withdrawal symptoms.

    People who will be continuing treatment with other mood stabilisers may have their antipsychotic dose tapered down over a four week period. People who will not be continuing other mood stabilisers may need to reduce their antipsychotic more slowly - usually over three months - to avoid a relapse.

    Typical antipsychotics

    This is the older group of medicines that includes drugs such as haloperidol (eg Haldol) and chlorpromazine.

    These medicines are very effective for controlling episodes of mania, but are less commonly used because they can have many unpleasant side effects. The most troublesome are abnormal involuntary facial and body movements that can occur after just a few doses.

    Other side effects include:

    • drowsiness and sedation
    • muscle tremor and rigidity
    • agitation
    • insomnia
    • dry mouth
    • constipation
    • blurred vision
    • confusion
    • dizziness
    • effects on the heart
    • weight gain
    • impotence
    • increases in levels of the hormone prolactin that may result in development of breasts and milk production.

      Atypical antipsychotics

      Atypical antipsychotics are newer medicines that are more likely to be used than the older antipsychotics. They are better tolerated than the older antipsychotics because they have fewer troublesome side effects.

      Atypicals include medicines such as aripiprazole (Abilify), clozapine (eg Clozaril), olanzapine (Zyprexa), quetiapine (Seroquel) and risperidone (Risperdal).

      Aripiprazole, olanzapine, quetiapine and risperidone are all licensed to treat episodes of mania.

      Aripiprazole and olanzapine are also licensed to prevent recurrence of mania in people whose manic episode responded to initial treatment with the medicine.

      Quetiapine is licensed to prevent both manic and depressive relapses in people whose manic, depressive or mixed episode responded to initial treatment.

      Clozapine is reserved for treating people with bipolar disorder who are highly unresponsive to other drugs, because it can cause serious side effects on the blood. It requires regular monitoring with blood tests.

      Further research is ongoing into the use of atypical antipsychotics in bipolar disorder and particularly in bipolar depression.

      Atypical antipsychotics cause less abnormal body and facial movements than the older drugs and have less effect on prolactin levels, though they still have the potential to cause these problems. Other side effects include:

      • sleepiness and sedation
      • weight gain
      • raised blood sugar levels and diabetes
      • raised cholesterol levels
      • sexual dysfunction
      • abnormal heart rhythms
      • dry mouth
      • constipation
      • blurred vision
      • drop in blood pressure and dizziness on standing up.

        During long-term treatment with atypical antipsychotics your doctor will want you to have regular check-ups to monitor things such as the levels of glucose, lipids and prolactin in your blood.

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