The efficiency of cabergoline vs pyridoxine for lactation inhibition-a randomized controlled trial

Some mothers may seek lactation inhibition on personal, social, or medical grounds. The common drug used for lactation inhibition is cabergoline. Several adverse effects and contraindications are known for this drug. Its use is contraindicated for patients with hypertensive disorders and fibrotic, cardiac, or hepatic diseases. In addition, pyridoxine (vitamin B6) has been used for this indication, with no significant adverse effect, following studies that demonstrated its efficacy.

This study aimed to compare the efficiency of cabergoline vs pyridoxine for lactation inhibition.

A randomized controlled trial was conducted. Postpartum patients who requested lactation inhibition were randomly allocated to receive either cabergoline (1 mg once on postpartum day 1 or divided to 0.25 mg twice a day for 2 days thereafter, according to the departmental protocol, which is in line with the manufacturer recommendations) or pyridoxine (200 mg 3 times a day for 7 days). The patients enrolled were free of diseases in which contraindications to cabergoline are present. All patients completed a questionnaire for assessing breast engorgement, breast pain, and milk leakage on a scale of 0 (no symptom) to 5 (severe symptom) on days 0, 2, 7, and 14. The primary outcome was lactation inhibition success, defined as a score of 0 for both engorgement and pain on day 7. The secondary outcomes included the assessment of milk leakage, adverse effects, fever, mastitis, and treatment discontinuation or alteration.

Of note, 45 and 43 patients received cabergoline or pyridoxine, respectively, and were included in the analysis following the intention-to-treat principle. Cabergoline was superior to pyridoxine in inhibiting lactation at day 7 (78% vs 35%, respectively; P<.0001). Mild symptoms, defined as a score of 0 to 2 for breast engorgement and pain, at day 7 were 40 (89%) in the cabergoline group and 29 (67%) in the pyridoxine group (P=.01). The incidence of milk leakage was lower in the cabergoline group after 7 and 14 days than in the pyridoxine group (9% vs 42% [P=.0003] and 11% vs 31% [P=.02], respectively). Cabergoline had more adverse effects than pyridoxine (31% vs 9%, respectively; P=.01), but all adverse effects were mild. The rates of mastitis and fever that were related to engorgement were similar in the cabergoline and pyridoxine groups (4 [9%] vs 2 [5%], respectively; P=.67). Furthermore, 9 patients (21%) in the pyridoxine group switched to or added cabergoline because of treatment failure. Accordingly, on day 7, the pyridoxine success rate was reduced from 35% (15 women) to 28% (12 women) and from 67% (29 women) to 53% (23 women) for a score of 0 and 0 to 2 for both engorgement and pain, respectively.

Cabergoline was superior to pyridoxine in inhibiting lactation. Cabergoline had more adverse effects, but no major adverse effect was documented in either treatment group. As pyridoxine inhibited lactation successfully in previous studies and in 67% of patients in this study, its use should be considered in women with contraindications for cabergoline.