Clonazepam 87Cancer.Not enough scientific information to report.
Pregnancy.No increase in birth defects was noted when pregnant rats and
mice received many times the recommended human dose while embryos were
in the organ-forming stage. Pregnant rabbits receiving clonazepam during the
same stage, however, have produced offspring with birth defects such as limb
malformations and cleft palate. Because other drugs in the benzodiazepine
class are assumed to have potential for causing human birth defects, clona-
zepam is considered inadvisable for pregnant women unless they and their
physicians have considered the issue. Among 51 infants whose mothers took
clonazepam during pregnancy, almost 10% had “major malformations”; al-
though that small sample did not compare outcomes in matched women who
took no such drug, the study’s finding nonetheless raises a caution. A much
larger study said that clonazepam taken in combination with other epilepsy
drugs increased the chance of birth defects but said nothing about using clona-
zepam alone. Clonazepam may disturb fetal heartbeat. Offspring with fetal
exposure may be sedated, show poor muscle tone, and have low body tem-
perature. Infants can be born with dependence to the drug. Clonazepam
passes into human milk at levels high enough to affect infants, and breast-
feeding mothers are counseled to avoid clonazepam.
Additional scientific information may be found in:
Cohen, L.S., and J.F. Rosenbaum. “Clonazepam: New Uses and Potential Problems.”
Journal of Clinical Psychiatry48 (1987, Suppl.): 50–56.
Commander, M., S.H. Green, and M. Prendergast. “Behavioural Disturbances in Chil-
dren Treated with Clonazepam.”Developmental Medicine and Child Neurology 33
(1991): 362–63.
Davidson, J.R., and G. Moroz. “Pivotal Studies of Clonazepam in Panic Disorder.”
Psychopharmacology Bulletin34 (1998): 169–74.
Davidson, J.R., et al. “Treatment of Social Phobia with Clonazepam and Placebo.”Jour-
nal of Clinical Psychopharmacology13 (1993): 423–28.
Morishita, S., S. Aoki, and S. Watanabe. “Clonazepam as a Therapeutic Adjunct to
Improve the Management of Psychiatric Disorders.”Psychiatry and Clinical Neu-
rosciences52 (1998): 75–78.
Rosenbaum, J.F., G. Moroz, and C.L. Bowden. “Clonazepam in the Treatment of Panic
Disorder with or without Agoraphobia: A Dose-Response Study of Efficacy,
Safety, and Discontinuance.”Journal of Clinical Psychopharmacology17 (1997):
390–400.
Worthington, J.J., III, et al. “Long-term Experience with Clonazepam in Patients with
a Primary Diagnosis of Panic Disorder.”Psychopharmacology Bulletin34 (1998):
199–205.