Bupropion (Wellbutrin ®, Zyban ®)
Antidepressant of the aminoketone class. Used in smoking cessation.
Molecular weight: 276.2
"Reproduction studies have been performed in rabbits and rats at doses up
to 15 to 45 times the human daily dose and have revealed no definitive
evidence of impaired fertility or harm to the fetus due to bupropion. (In
rabbits, a slightly increased incidence of fetal abnormalities was seen in 2
studies, but there was no increase in any specific abnormality)." 
As of February 2003, 764 pregnancies involving exposure to bupropion
had been prospectively registered with The Glaxo Wellcome Bupropion
Pregnancy Registry. As of June 2003, 154 pregnancies were pending
delivery, 213 cases were lost to follow up, and 397 cases with 401 outcomes
were obtained. The indications for use of bupropion in the latter were
depression in 251 patients, smoking cessation in 95 patients, depression and
smoking cessation in 16 patients, bipolar affective disorder in one patient,
and unspecified in 34 patients.
Of 322 outcomes involving bupropion exposure in the first trimester there
were 261 live births without birth defects, 40 spontaneous pregnancy losses,
11 induced abortions, 1 induced abortion with evidence of Down syndrome on
prenatal testing, and 9 infants born alive with birth defects.
The defects in infants born alive included one infant with
bilateral club feet, one infant with Klinefelter's syndrome (no
physical abnormalities), and 7 infants with heart defects (1
abnormal aortic valve thickening with mild aortic insufficiency, 1
ventricular septal defect, 1 trivial pulmonic stenosis with atrial septal
defect, 1 coarctation with ventricular septal defect, 1 thickened heart
muscle, 1 pulmonary stenosis, and 1 coarctation of the aorta).
The observed proportion of birth defects in pregnancies with prenatal
exposure to bupropion in the first trimester was 3.7%.
The registry's Advisory Committee noted the increased number of
prospective reports of defects involving the heart and great vessels. Given
the small sample size and the potential bias from the large percentage of
cases lost to follow up an accurate assessment of a potential effect of bupropion on the developing cardiovascular system could not be made. To
further evaluate the possible association of bupropion with
cardiovascular defects The Committee plans to conduct a retrospective
cohort study entitled "Bupropion in Pregnancy and the Risk of Cardiovascular
and Overall Major Congenital Malformations". (2).
Healthcare providers can obtain interim registry results and register
patients by calling the registry project office directly at 1-800-336-2176
(toll-free) or (910) 256-0549 (collect)
BREAST FEEDING: Bupropion is excreted into human milk. In one mother
taking bupropion 100 mg three times daily peak milk concentrations occurred 2
hours after a 100 mg dose, The milk-to-plasma
ratio ranged between 2.49 and 8.72 over 6 hours after after a 100-mg
dose. Bupropion and its metabolites were not detected in the infant's plasma .
Milk-to-plasma ratios ranged from 2.51 to 8.58 over a six-hour interval.
Baab SW et al. reported no quantifiable levels of bupropion nor its active
metabolite hydroxybupropion were found in serum samples of two breast fed
infants after maternal ingestion of either bupropion 75 mg b.i.d. or bupropion
SR 150 mg daily.
The infants studied in the above reports were all healthy infants at least
several months of age. These results may not be applicable to newborns or
infants with health problems.
The American Academy of Pediatrics has classified bupropion as a drug "for which the effect on nursing infants is unknown but may be of concern"
1. Physicians Desk Reference 57th ed. Montvale, NJ: Thomson PDR;
2. Glaxo Wellcome Bupropion Pregnancy Registry 9/1/97 – 2/28/03. Issued
June 2003. Research Triangle Park, North Carolina. 13p.
3. Briggs GG, et al., Excretion of bupropion in breast milk. Ann Pharmacother. 1993;27:431-3.MEDLINE
4. Baab SW, et al. Serum bupropion levels in 2 breastfeeding mother-infant pairs.J Clin Psychiatry. 2002;63:910-1. MEDLINE
5.Transfer of drugs and other chemicals into human milk. Pediatrics. 2001 Sep;108(3):776-89. Review.