Is Zonisamide safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Zonisamide. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
A patient taking zonisamide 300 mg orally 3 times daily as well as other unspecified antipsychotics was followed at 0, 3, 14 and 30 days postpartum. Her infant exhibited no behavioral problems.[ 3 ] Two infants were breastfed postpartum by their mothers. One was exclusively breastfed for 9 days postpartum, then breastfed twice daily and supplemented with formula 7 to 8 times daily. The maternal zonisamide dose was 300 mg (6.2 mg/kg) daily. On day 34, the infant was healthy, had gained weight and had experienced no observable adverse effects. The second infant was partially breastfed by a mother taking zonisamide 100 mg (2.1 mg/kg) daily. No adverse reactions were noted in the infant during the first 2 weeks postpartum, at which time breastfeeding was discontinued because of a low milk supply.[ 1 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
In published reports of anticonvulsant use during breastfeeding, most women were taking a combination of anticonvulsants. Some other anticonvulsants (e.g., phenytoin, carbamazepine) stimulate the metabolism of other drugs including anticonvulsants, whereas others (e.g., valproic acid) inhibit the metabolism of other drugs. Therefore, the relationship of the maternal dosage to the concentration in breastmilk can be quite variable, making calculation of the weight-adjusted percentage of maternal dosage less meaningful than for other drugs in this database. Maternal Levels . A woman took zonisamide monotherapy (dosage and regimen not specified) during pregnancy and postpartum. Two serum concentrations were measured: 13.6 mg/L at 3 hours before delivery and 23.2 mg/L on day 17 postpartum. Milk samples were collected postpartum and measured for zonisamide using untreated breastmilk in an enzyme immunoassay. Milk levels were 4.6 mg/L at 58 hours postpartum, 13.6 at 61 hours postpartum, and 19.2 mg/L at 77 hours postpartum.[ 2 ] A mother was taking oral zonisamide 300 mg daily. Milk levels measured 1.5 hours after her dose on days 6 and 30 postpartum were 9.75 and 10.5 mg/L, respectively. Milk levels measured 2.5 hours after her dose on days 3 and 15 postpartum were 8.25 and 9.12 mg/L, respectively.[ 3 ] The same authors reported that patients (number and time postpartum unspecified) taking oral zonisamide 300 mg daily had an average (+/ SD) breastmilk level of 9.41 +/ 0.95 mg/L.[ 4 ] These values are exactly the same as the average and standard deviation of the former patient s 4 milk levels. It is likely that these results are merely a duplicate of the above results. A mother who was taking oral zonisamide 400 mg, carbamazepine 1 g, and clonazepam 1 mg daily had breastmilk whey levels of zonisamide measured 9 times from day 1 to day 10 postpartum. All of the levels were distributed (neither increasing nor decreasing) in the range of 8.9 to 10.9 mg/L.[ 5 ] Using data from
Alternatives LactMed lists
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.