Prescribing Guidelines for antipsychotic drugs
1. Before choosing a drug, always review the patient's history and records as thoroughly as possible to get evidence of past response to drugs and / or adverse effects.
2. Efficacy should be systematically monitored and recorded, if possible using standard rating scales for mental state, possibly augmented by a broader assessment of clinical response (e.g. Brenner's scale).
3. Details of lack of efficacy or intolerance should be explicitly recorded.
4. Intramuscular (IM) doses of antipsychotics are lower than equivalent oral doses and should be prescribed separately. The prescription should not imply that the same dose can be given orally or IM.
5. If a patient is given "as required" antipsychotic medication (e.g. in an acute psychotic episode, after inpatient admission), the dose should be reviewed at least every 3 days (preferably daily), and the regular dose adjusted accordingly.
6. Avoid whenever possible frequent changes in drug dose. Given that antipsychotic drugs may not exert full antipsychotic effects for 4-6 weeks, if a patient shows disturbed behaviour early in the treatment, consider adding a benzodiazepine rather than increasing the dose of the antipsychotic.
7. A reasonable approach to the use of antimuscarinic drugs is:
- Patients with a history of acute dystonia or known vulnerability to develop extrapyramidal symptoms (EPS): prescribe an antimuscarinic prophylactically.
- Other patients: use an antimuscarinic in patients who develop EPS.
- This approach applies to both oral and depot antipsychotics. Antimuscarinics have side-effects of their own. When an antimuscarinic is used, try to reduce the dose or stop the drug at regular intervals, e.g. by withdrawing it every 3 months or so and examining the patient for evidence of emergent EPS.
8. There is no convincing evidence that administration of two or more antipsychotics concurrently and regularly has any advantage over the use of a single antipsychotic. Concurrent use of more than one antipsychotic has the disadvantage that it becomes difficult to calculate the total antipsychotic dose.
9. There are few data to support any benefit of high dose antipsychotics and the incidence of side-effects is increased. Avoid high doses whenever possible (see algorithm).
10. Brenner HD, Dencker SJ, Goldstein MJ, Hubbard JW, Keegan DL, Kruger G, Kulhanek F, Liberman RP, Malm U, Midha KK. Defining treatment refractoriness in schizophrenia. Schizophrenia Bulletin 1990; 16: 551-61.
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