Ribociclib

It is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. It is used to treat advanced or metastatic breast cancer oestrogen-receptor positive and human epidermal growth factor receptor 2 (HER2) negative. Oral administration once a day.

At the date of the last update we did not find any published data on its excretion in breast milk.

Its low percentage of protein binding and long elimination half-life makes it likely that significant amounts will pass into breast milk.

Diarrhea, loss of appetite, infections, leukopenia, neutropenia, anemia, and hepatotoxicity are common adverse reactions.

It is known via Pharmacokinetics that after 3 elimination half-lives (T½) 87.5% of the drug is eliminated from the body; after 4 T½ 94%, after 5 T½ 96.9%, after 6 T½ 98.4% and after 7 T½ 99%. Plasma drug concentrations in the body are negligible after 7 T½. In general, a period of al least five half-lives may be considered a safe waiting period before returning to breastfeeding. ^{(Anderson 2016)}

Taking the longest published T½ (55 hours) these 5 T½ would correspond to 11 days. Meanwhile, express and discard milk from the breast regularly to maintain production.  This does not allow breastfeeding during treatment.

See below the information of this related product:

• Maternal Cancer; Maternal Neoplasia (Unsafe. Moderate/severe adverse effects. Compatible under certain circumstances. Follow-up recommended. Use safer alternative or discontinue breastfeeding from 5 to 7 T ½ . Read Commentary.)