كلادريبين

It is an analogue of the purine nucleoside that inhibits the synthesis and repair of DNA.
It is used as an antineoplastic in the treatment of certain types of leukemias and in multiple sclerosis.
It is administered parenterally daily for 7 days, subcutaneously daily for 5 days in cycles every 28 days.
In the treatment of multiple sclerosis it is administered orally every 24 hours for 5 days, the first week of the month for two months. The treatment is repeated after one year.

Since the last update we have not found published data on its excretion in breastmilk.

Its pharmacokinetic data (low molecular weight, low protein binding) makes it possible that it could transfer into milk in amounts that could be significant.

It is known from pharmacokinetics that after 3 elimination half-lives (T½), 87.5% of the drug is eliminated from the organism; after 4 T½ it is 94%, after 5 T½, 96.9%, after 6 T½, 98.4% and after 7 T½, 99%. From 7 T½ the plasma concentrations of the drug in the body are negligible. In general, a period of at least five half-lives can be considered a safe waiting period before breastfeeding again (Anderson 2016).

There is considerable variability in the published elimination half-life of this drug (Janssen 2018): from 5.4 hours (Janssen 2018), passing through 6.7 hours (Liliemark 1991), 10 hours (Juliusson 2006), 16 hours (Janssen) 2018 and Lindemalm 2005) up to 21 hours (Albertini 1998), possibly influencing the patient's renal function status (Janssen 2018).

Taking as reference the longest published T½ of all the active metabolites (21 hours) these 5 T½ would correspond to 4 and a half days. Due to the major adverse effects, it would be advisable to wait 7 T½, which would correspond to 6 days. Meanwhile, express and discard milk from the breast regularly.
If renal function is normal, some authors recommend waiting 48 hours after the last dose before resuming breastfeeding (Almas 2016).

When it is possible to do so, milk detections of each patient to determine the total elimination of the drug would be the best indicator for resuming breastfeeding between two cycles of chemotherapy.

Other authors suggest the possibility of postponing treatment until breastfeeding has stopped, in cases where the course of the disease is slow. (Alothman 1994).

During the treatment of cancer, breastfeeding should be interrupted temporarily due to potentially serious side effects for the infant. Chemotherapy does not affect milk production during or after treatment.
Abrupt weaning can be psychologically traumatic for both the mother and the infant (Pistilli 2013). If the mother wishes, production of milk can be maintained by regularly expressing breastmilk, being able to resume breastfeeding in the periods in which no significant traces of the drug remain in the milk (Anderson 2016) or at the end of the treatment (Pistilli 2013).

Some chemotherapeutic agents with antibiotic effect can alter the composition of the microbiota (bacterial set or bacterial flora) of the milk and the concentration of some of its components (Urbaniak 2014). This possibly occurs temporarily with subsequent recovery, although no harmful effects are assumed or reported in breastfed infants.

Women undergoing chemotherapy during pregnancy have lower rates of breastfeeding because they experience difficulties in breastfeeding (Stopenski 2017), needing more support to achieve it.

Given the strong evidence that exists regarding the benefits of breastfeeding for the development of babies and the health of mothers, it is advisable to evaluate the risk-benefit of any maternal treatment, including chemotherapy, individually advising each mother who wishes to continue with breastfeeding (Koren 2013).