The maximum recommended dose for haloperidol has been reduced from 100 mg (rarely 120 mg) to 30 mg a day for oral therapy and from 60 mg to 18 mg a day for intramuscular administration in the latest edition of the British National Formulary (BNF 40; British Medical Association & Royal Pharmaceutical Society, 2000). This dosage change has not been widely publicised; we only became aware of it through a message posted on the UK Psychiatric Pharmacists' website by a pharmacist, Margaret Rotchell. It appears that the changes to the maximum recommended dosage of Serenace (manufactured by Norton Healthcare) were made to the drug's licence back in September 1998 but have not been brought to the attention of doctors and pharmacists.

The dosage change has implications for patients who are receiving haloperidol on a Form 38 or 39, as the dosage they are receiving may no longer be ‘within BNF limits’ and therefore may not be covered by these forms. Inevitably, more patients will now be considered as being on ‘high dose’ antipsychotic therapy and should be the subject of physical monitoring (Reference ThompsonThompson, 1994). Strictly speaking, these patients should be made aware that they are now on high dose therapy and this may affect their consent to treatment.