Methadone 273Methadone should be used cautiously if a person is also taking monoamine
oxidase inhibitors (MAOIs, found in some antidepressants and other medi-
cine). Blood levels of methadone can be drastically altered byphenobarbital,
by the epilepsy medicines phenytoin and carbamazepine, and by the tuber-
culosis medication rifampin. A case report notes that the HIV/AIDS (human
immunodeficiency virus/acquired immunodeficiency syndrome) drug rito-
navir reduces methadone blood levels, and methadone interacts with other
HIV/AIDS drugs as well. Taking doses of methadone along with the
psychiatric medicine fluvoxamine (Luvox) can be fatal. Depending on how a
person uses alcohol, that drug can raise or lower blood levels of methadone.
Data from one study showed that methadone did not decrease likelihood for
alcohol abuse and that persons already abusing alcohol drank even more
while on methadone. Other drug combinations common among illicit users
can be hazardous with methadone, and methadone alone can be dangerous if
a person who once had tolerance resumes usage at the old high-dose level.
Experiments have found that consumption and enjoyment of tobacco ciga-
rettes increase after volunteers use methadone, and another experiment found
that methadone consumption increases after volunteers usenicotine(in gum
or cigarettes).
Cancer.Chromosome damage is one measure of a drug’s potential for caus-
ing cancer. A study of persons receiving methadone for 40 weeks found no
more chromosome damage than a nondrug population would have.
Pregnancy.Safety for use during pregnancy is unknown. Researchers who
gave various opioids to pregnant hamsters described methadone as one of the
most powerful inducers of birth defects. Mice research shows that offspring
are smaller than normal but have ordinary brain development. Compared to
morphine, much more of a maternal methadone dose reaches a fetus. One
group of investigators developed findings implying that methadone may
harm human fetal central nervous system development. Those discoveries are
consistent with research demonstrating abnormal development of neurons in
rats that had prenatal methadone exposure; researchers speculate that such
abnormalities may explain various behaviors in human infants who had pre-
natal methadone exposure. Use of methadone for easing pain of childbirth is
not recommended because newborns can suffer breathing difficulty after pick-
ing up the drug from the maternal blood supply. Infants from women who
use methadone chronically can be born with dependence to the drug.
A study compared pregnant women on methadone maintenance to a preg-
nant group on morphine maintenance and discovered that the morphine
group used fewer benzodiazepine class drugs and fewer opiates than the
methadone program participants. Another study noted that pregnant addicts
in a methadone program received better prenatal care than addicts who were
not in such programs, but program participants typically continued illicit drug
use, their infants weighed no more than infants from pregnant addicts not in
a methadone program, and infants from both those drug groups (program
and nonprogram) weighed less than those of women who were not drug abus-
ers. Such results have led more than one group of researchers to ask whether
methadone maintenance helps pregnancy outcomes, but those researchers do