Pharmacological treatment strategies for lowering prolactin in people with a psychotic disorder and hyperprolactinaemia: A systematic review and meta-analysis

Different therapeutic strategies are used for lowering prolactin concentrations in patients with psychotic disorders with antipsychotic-induced hyperprolactinaemia. We aimed to examine the evidence from open-label studies and randomized clinical trials (RCTs) that studied four prolactin-lowering therapeutic strategies in people with psychotic disorders and hyperprolactinaemia: 1) switching to prolactin-sparing antipsychotics; 2) adding aripiprazole; 3) adding dopamine agonists; and 4) adding metformin. RCTs were included in a meta-analysis. Effect sizes (Hedges' g) of prolactin reductions with each strategy were calculated. Withdrawal rates were also considered. We identified 26 studies. Nine studies explored switching antipsychotic treatment to aripiprazole (n = 4), olanzapine (n = 1), quetiapine (n = 2), paliperidone palmitate (n = 1) or blonanserin (n = 1). Twelve studies tested the addition of aripiprazole. Six studies explored the addition of cabergoline (n = 3), bromocriptine (n = 2) or terguride (n = 1). We also found one meta-analysis testing the addition of metformin to antipsychotic treatment but no other individual studies. A meta-analysis could only be performed for the addition of aripiprazole, the strategy with the best level of evidence. Five RCTs testing the addition of aripiprazole yielded a significant reduction in prolactin concentration compared to placebo (N = 3) or maintaining antipsychotic treatment (N = 2): Hedges' g was −1.35 (CI 95%: −1.93 to −0.76, p