The average dose has tended to rise over the years. This is despite the fact that the most effective dose may be quite low; that increasing the dose will probably not make it more effective; and that it may make the side effects worse. Since the advent of the atypical drugs this trend has reversed, and indeed research has suggested that atypical drugs have no advantages over the older drugs if the older ones are used at the lowest effective dose.
Doses should be kept as low as possible. High doses can have a zombie-like effect, giving you a mask-like expression and strange movements. It can make it very difficult for you to move normally, to get up and get going in the morning, and to take part in normal activities and social events. Moderate to high doses increase the risk of tardive dyskinesia, which is a serious problem causing involuntary movements. Research suggests that low, maintenance doses are as effective in preventing relapse as higher doses. Older people need smaller doses of drugs, and their health is at risk if they are given too high a dose.
Chlorpromazine (Largactil) can be prescribed in tablet form to physically healthy adults in doses ranging from 75mg up to 1g (1000mg) daily. The aim should be to find the dose that lets you lead as normal a life as possible. If the medication is not working, it’s important for doctors to reconsider the treatment rather than automatically putting up the dose.
The National Institute for Clinical Excellence (NICE) current guidelines on the treatment of schizophrenia suggest that doctors prescribe antipsychotics at the lowest effective dose, introducing the drugs gradually. They suggest that people should not be given a high starting dose.
Maximum Dosage
Among other information, the British National Formulary (BNF) gives maximum doses for some, but not all, of the antipsychotics. Generally, the drugs aren’t licensed for use above these dosages, but hospital doctors do exceed them, at their discretion. They may also prescribe medication to be given ‘as necessary’ (p.r.n.), which can mean in addition to your regular dose. As a result, your total dose could be above the BNF maximum, although your psychiatrist has a duty to review the total dosage, daily.
If you are worried about your diagnosis and treatment and unsure about the advice you have been given, you could ask either your GP or psychiatrist to refer you for a second opinion.