Arsénieux, anhydride

Inorganic form of arsenic used for the treatment of acute promyelocytic leukemia. Intravenous administration. A daily dose until remission or a maximum of 50-60 days and then 5 weekly doses for 4 to 5 weeks, several cycles separated by 4 weeks of rest. ^{(EMA 2018)}

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

During cancer treatment, breastfeeding must be interrupted due to potentially serious side effects for the infant.

It is known from pharmacokinetics that after 3 elimination half-lives (T½) 87.5% of the drug is eliminated from the body; after 4 T½ 94% is eliminated, 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)}

Although expert authors report waiting times before breastfeeding of 1 week after the last dose (LactMed 2018), taking into account the long half-life of the DMA metabolite (70 hours), it seems more prudent, as indicated by the manufacturer (Teva 2018), to wait 15 days (5 T½ of the metabolite DMA and 25 T½ of the parent compound) after the last dose to restart breastfeeding. Meanwhile, express and discard breast milk regularly in order to maintain production.

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

Continued and long treatment cycles make it very difficult to continue with breastfeeding.

Some chemotherapeutic agents with an 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 due to difficulties in breastfeeding ^{(Stopenski 2017)}, needing more support to achieve it.

Given the strong evidence that exists on 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 that wishes to continue with breastfeeding.^{(Koren 2013)}

See below the information of this related product:

• Maternal Cancer (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.)