Are atypical antipsychotics safe during breast feeding?
Background
Unlike first-generation antipsychotic drugs which act predominantly by blocking dopamine D2 receptors, second-generation antipsychotics (SGAs - also known as atypical antipsychotics) act on a range of receptors (1). SGAs are less likely to cause extrapyramidal symptoms (EPS) and tardive dyskinesia but this may be balanced by a greater risk of metabolic effects. The main difference between the two groups is the size of the therapeutic index for acute EPS. This value is very narrow for haloperidol whereas it is wide for olanzapine (2).
In the UK, seven SGAs are licensed for the treatment of schizophrenia. Some are licensed for additional indications such as manic episodes, bipolar disorder, schizoaffective disorder, psychotic disorders associated with Parkinson’s disease and aggression in moderate to severe Alzheimer’s disease (1).
The NICE 2009 guideline for schizophrenia no longer recommends prescribing SGAs as first line treatment but suggests that benefits and side effect profiles of individual drugs should be discussed with the patient to inform choice (3).
Answer
Amisulpride, aripiprazole, clozapine, olanzapine, quetiapine and risperidone have all been detected in breast milk (4). Although no data are available for the use of paliperidone during
breastfeeding, it is the active metabolite of risperidone. 9-hydroxyrisperidone has been detected in breast milk following maternal use of risperidone (5, 6). Infant intake of SGAs via milk has been estimated between 0.09% (quetiapine) (7) and 10.7% (amisulpride) of the weight adjusted maternal dose (8).
SGAs have relatively long half-lives: see Table 1 below. The long half-lives and reduced drug clearance, especially in neonates and young infants, can lead to drug accumulation and an increased risk of adverse reactions following chronic exposure to the drugs via breast milk (9).