A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Mifeprex (RU486) Side Effects, and Drug Interactions - Mifepristone
Mifeprex (RU486) Side Effects, and Drug Interactions - Mifepristone
SIDE EFFECTS
The treatment procedure is designed to induce the vaginal bleeding and
uterine cramping necessary to produce an abortion. Nearly all of the women
who receive Mifeprex and misoprostol will report adverse reactions, and
many can be expected to report more than one such reaction. About 90%
of patients report adverse reactions following administration of misoprostol
on day three of the treatment procedure. Those adverse events that occurred
with a frequency greater than 1% in the U.S. and French trials are shown
in Table 3.
Bleeding and cramping are expected consequences of the action of Mifeprex
as used in the treatment procedure. Following administration of mifepristone
and misoprostol in the French clinical studies, 80 to 90% of women reported
bleeding more heavily than they do during a heavy menstrual period (see
WARNINGS, Bleeding for additional
information). Women also typically experience abdominal pain, including
uterine cramping. Other commonly reported side effects were nausea, vomiting
and diarrhea. Pelvic pain, fainting, headache, dizziness, and asthenia
occurred rarely. Some adverse reactions reported during the four hours
following administration of misoprostol were judged by women as being
more severe than others: the percentage of women who considered any particular
adverse event as severe ranged from 2 to 35% in the U.S. and French trials.
After the third day of the treatment procedure, the number of reports
of adverse reactions declined progressively in the French trials, so that
by day 14, reports were rare except for reports of bleeding and spotting.
Table 3
|
Type of Reported Adverse Events Following Administration
of Mifepristone and Misoprostol in the U.S. and French Trials*
(percentages)
|
| |
U.S. Trials
|
French Trials
|
| Abdominal Pain (cramping) |
96
|
NA
|
| Uterine cramping |
NA
|
83
|
| Nausea |
61
|
43
|
| Headache |
31
|
2
|
| Vomiting |
26
|
18
|
| Diarrhea |
20
|
12
|
| Dizziness |
12
|
1
|
| Fatigue |
10
|
NA
|
| Back pain |
9
|
NA
|
| Uterine hemorrhage |
5
|
NA
|
| Fever |
4
|
NA
|
| Viral infections |
4
|
NA
|
| Vaginitis |
3
|
NA
|
| Rigors (chills/shaking) |
3
|
NA
|
| Dyspepsia |
3
|
NA
|
| Insomnia |
3
|
NA
|
| Asthenia |
2
|
1
|
| Leg pain |
2
|
NA
|
| Anxiety |
2
|
NA
|
| Anemia |
2
|
NA
|
| Leukorrhea |
2
|
NA
|
| Sinusitis |
2
|
NA
|
| Syncope |
1
|
NA
|
| Decrease in hemoglobin
greater than 2 g/dL |
NA
|
6
|
| Pelvic pain |
NA
|
2
|
| Fainting |
NA
|
2
|
| * Only adverse reactions with incidence
>1% are included. |
DRUG INTERACTIONS
Although specific drug or food interactions with mifepristone have not
been studied, on the basis of this drug’s metabolism by CYP 3A4,
it is possible that ketoconazole, itraconazole, erythromycin, and grapefruit
juice may inhibit its metabolism (increasing serum levels of mifepristone).
Furthermore, rifampin, dexamethasone, St. John’s Wort, and certain
anticonvulsants (phenytoin, phenobarbital, carbamazepine) may induce mifepristone
metabolism (lowering serum levels of mifepristone).
Based on in vitro inhibition information, coadministration of
mifepristone may lead to an increase in serum levels of drugs that are
CYP 3A4 substrates. Due to the elimination of mifepristone from the
body, such interaction may be observed for a prolonged period after its
administration. Therefore, caution should be exercised when mifepristone
is administered with drugs that are CYP 3A4 substrates and have narrow
therapeutic range, including some agents used during general anesthesia.
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