Antipsychotics and Antimania

Question 1

Typical Anti-psychotics (chlorpromazine, haloperidol): Mechanism of action

Answer 1

The first-generation antipsychotic drugs act predominantly by blocking dopamine D2 receptors in the brain. First-generation antipsychotic drugs are not selective for any of the four dopamine pathways in the brain and so can cause a range of side-effects, particularly extrapyramidal symptoms and elevated prolactin.

Question 2

Typical Anti-psychotics (chlorpromazine, haloperidol): Indications

Answer 2

Most antipsychotics are licensed for use in schizophrenia, mania, and other psychoses. As with many drugs in psychiatry they are sometimes used outside of license.

In the short term they are used to calm disturbed patients whatever the underlying psychopathology, which may be schizophrenia, brain damage, mania, toxic delirium, or agitated depression. Antipsychotic drugs are used to alleviate severe anxiety but this too should be a short-term measure.

Question 3

Typical Anti-psychotics (chlorpromazine, haloperidol): Side Effects

Answer 3

• Extrapyramidal side-effects
• Hyperprolactinaemia
• Reduced seizure threshold
• Postural hypotension
• Anticholinergic: dry mouth, constipation
• Metabolic: Weight gain, diabetes, hyperlipidaemia
• Neuroleptic malignant syndrome (NMS)

Question 4

Typical Anti-psychotics (chlorpromazine, haloperidol): Cautions/ Contraindications

Answer 4

Neuroleptic malignant syndrome (NMS)

Neuroleptic malignant syndrome (hyperthermia, fluctuating level of consciousness, muscle rigidity, and autonomic dysfunction with pallor, tachycardia, labile blood pressure, sweating, and urinary incontinence) is a rare but potentially fatal side-effect of all antipsychotic drugs.

FBC, U/E, and LFT monitoring is required at the start and then annually thereafter.

Blood lipids and weight should be measured at baseline, at 3 months, and then yearly.

Fasting blood glucose should be measured at baseline, at 4–6 months, and then yearly.

Before initiating antipsychotic drugs, an ECG may be required

Blood pressure monitoring is advised before starting therapy and frequently during dose titration of antipsychotic drugs.

Question 5

ATypical Anti-psychotics (): Mechanism of action

Answer 5

The second-generation antipsychotic drugs (sometimes referred to as atypical antipsychotic drugs) act on a range of receptors in comparison to first-generation antipsychotic drugs and have more distinct clinical profiles, particularly with regard to side-effects.