Background: Haloperidol is a benchmark, accessible antipsychotic drug against which the effects of newer treatments are gauged.
Objectives: To determine the best range of doses for haloperidol for the treatment of people acutely ill with schizophrenia.
Search methods: We searched the Cochrane Schizophrenia Group Trials Register (February 2010), which is based on regular searches of CINAHL, EMBASE, MEDLINE and PsycINFO.
Selection criteria: We selected studies if they involved people being treated for acute schizophrenia, randomised to two or more dose ranges of non-depot haloperidol, and if they reported clinically meaningful outcomes.
Data collection and analysis: For this update, we inspected all citations and independently re-inspected a sample of citations in order to ensure reliable selection. We resolved any disagreement by discussion, and where doubt remained, we acquired the full-text article for further inspection. We then ordered papers, and reliably re-inspected and quality assessed the full reports, and extracted data. For homogeneous dichotomous data, we calculated the risk ratio (RR) with 95% confidence intervals (CI) on an intention-to-treat (ITT) basis. We assumed that people who left the study early or were lost to follow-up had a negative outcome. We calculated mean differences (MD) for continuous outcomes that reported ITT, last observation carried forward (LOCF) data. We excluded data if loss to follow-up was greater than 50%.
Main results: We included 19 trials with 19 different randomised dose comparisons. No studies reported data on relapse rates or quality of life and only one compared low dose (> 1.5 to 3 mg/day) haloperidol to higher dose ranges. Using standard lower dose (> 3 to 7.5 mg/day) did not result in loss of efficacy (no clinically important improvement in global state, versus standard higher dose (> 7.5 to 15 mg/day, n = 48, 1 RCT, RR 1.09, 95% CI 0.7 to 1.8, very-low-quality evidence); versus high dose (> 15 to 35 mg/day, n = 81, 2 RCTs, RR 0.95, 95% CI 0.8 to 1.2, very-low-quality evidence). Doses of haloperidol in the range of > 3 to 7.5 mg/day had a lower rate of development of clinically significant extrapyramidal adverse effects than higher doses (clinically significant extrapyramidal adverse effects, versus standard higher dose, n = 64, 2 RCTs, RR 0.12, 95% CI 0.01 to 2.1, very-low-quality evidence); versus high dose, n = 144, 3 RCTs, RR 0.59, 95% CI 0.5 to 0.8, very-low-quality evidence; versus very high dose (> 35 mg/day, n = 86, 2 RCTs, RR 0.70, 95% CI 0.5 to 1.1, very-low-quality evidence). None of the other comparisons between dose ranges yielded statistically significant differences, but several, particularly with lower dose ranges, were underpowered to detect clinically meaningful differences.
Authors' conclusions: Noresults were conclusive and all were based on small, short studies of limited quality. However, it would be understandable if clinicians were cautious in prescribing doses in excess of 7.5 mg/day of haloperidol to a person with uncomplicated acute schizophrenia, and if people with schizophrenia were equally reticent to take greater doses. Further research is needed regarding the efficacy and tolerability of the lower dose ranges, especially > 1.5 to 3 mg/day.