Is cabergoline a better drug to inhibit lactation in patients with psychotic symptoms?

Three cases of postpartum psychosis were diagnosed at the psychiatric inpatient clinic of our hospital recently. The patients were prescribed antipsychotic medication (2 mg/d of risperidone [n = 2], 4 mg/d of haloperidol [n = 1]) and the new ergot-derived drug cabergoline to inhibit puerperal lactation. Cabergoline did not worsen psychotic symptoms, and lactation was completely suppressed in each case. As a result of these cases, we became interested in the role of cabergoline as a new treatment to inhibit lactation in patients with psychosis, as well as in its mechanism of action compared with other ergot derivatives used for this purpose.

Since its introduction in the early 1970s, bromocriptine has been the recommended drug for the suppression of lactation.1 The optimal dosage to prevent lactation is 2.5 mg on the first day, increasing to twice daily for 14 days; to suppress lactation the dosage is 2.5 mg/day for 3 days, increasing to twice daily until day 14. The most frequently reported adverse effects are drowsiness, nausea and headache, but psychosis has also been reported.2,3 In addition, bromocriptine has been reported to worsen psychotic symptoms in patients suffering from schizophrenia, other psychotic disorders or psychotic depression.4

Introduced in the mid 1990s, cabergoline can be used to inhibit puerperal lactation; other uses include the treatment of Parkinson's disease, prolactinomas, acromegaly, and amenorrhea and galactorrhea secondary to neuroleptic use.5 This dopamine agonist has a higher specificity and affinity for the dopamine D₂ receptor than bromocriptine,6 and the suppression of prolactin release is longer lasting with cabergoline than with bromocriptine.7,8 Morissette et al9 also reported that cabergoline possesses a similar affinity, in the nanomolar range, for D₂ and D₃ receptors. A single dose of 1 mg of cabergoline is used to inhibit lactation on the first postpartum day, and 0.25 mg twice a day for 2 days suppresses established lactation. Adverse effects are similar to other ergot derivatives, but cabergoline appears to be better tolerated.8 Some studies report less intense adverse effects with cabergoline than with bromocriptine.9

To our knowledge, no cases of psychosis or worsening of previous psychotic disorders have been reported with cabergoline. However, fewer reports of adverse effects could be related to the length of time it has been in use. As well, treatment with cabergoline is much shorter than with bromocriptine; the shorter duration of D₂ agonism may make psychotic symptoms less likely. It is also possible that cabergoline has more specific affinity for some dopamine pathways (e.g., tuberoinfundibular, nigrostriatal) than others (e.g., mesolimbic pathway, which is related to psychotic symptoms). In any case, it is likely that compliance — an important consideration for patients with psychotic symptoms — would be better with the few required doses of cabergoline.

Cabergoline could be the treatment of choice to inhibit lactation in patients with postpartum psychosis and in those suffering from other psychotic disorders.