Medical abortion in lactating women--low levels of mifepristone in breast milk.
OBJECTIVE
Medical abortion using mifepristone followed by misoprostol is increasingly used for termination of an unwanted pregnancy. Consequently, an increasing number of women undergo medical abortion while still breastfeeding from a previous pregnancy. But there are no data on mifepristone use during lactation. We studied the levels of mifepristone in breast milk collected from women undergoing medical abortion. DESIGN AND SAMPLES: Samples of milk were collected from 12 women during the first 7 days after intake of either 200 mg (n = 2) or 600 mg (n = 10) of mifepristone. In addition, serum samples were collected on day 3 (n = 4). Main outcome measures. The levels of mifepristone, quantified using radioimmunoassay.


RESULTS
The milk concentrations of mifepristone were highest in the first samples collected during the first 12 hours following drug intake, and ranged from undetectable (< 0.013 micromol/l) to 0.913 micromol/l. Thereafter, declining concentrations of mifepristone were detected up to 7 days. The lowest levels of mifepristone in milk were measured following ingestion of the 200 mg dose. The milk:serum ratio of mifepristone ranged from < 0.013:1 to 0.042:1 on day 3 (n = 4). The calculated relative infant dose (RID) was 1.5% at its highest.


CONCLUSIONS
The levels of mifepristone in milk are low, especially when using the 200 mg dose. Breastfeeding can be safely continued in an uninterrupted manner during medical abortion of this kind.
Sääv
Ingrid
I
Department of Woman and Child Health, Division of Obstetrics and Gynecology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
Fiala
Christian
C
Hämäläinen
Jonna M
JM
Heikinheimo
Oskari
O
Gemzell-Danielsson
Kristina
K
D000021:Abortifacient Agents, Steroidal / Q000008:administration & dosage / Q000032:analysis* / Q000493:pharmacokinetics; D000028:Abortion, Induced / Q000379:methods; D000284:Administration, Oral; D000328:Adult; D001942:Breast Feeding; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007774:Lactation / Q000187:drug effects; D015735:Mifepristone / Q000008:administration & dosage* / Q000032:analysis* / Q000493:pharmacokinetics; D008895:Milk, Human / Q000737:chemistry*; D011247:Pregnancy; D011275:Pregnancy, Unwanted / Q000187:drug effects; D011446:Prospective Studies; D011863:Radioimmunoassay; D018570:Risk Assessment; D017751:Safety Management; D013997:Time Factors; D016896:Treatment Outcome
D000021:Abortifacient Agents, Steroidal; D015735:Mifepristone