Fosamax plus d Pregnancy Warnings
Alendronate:
Reproduction studies in rats showed decreased postimplantation survival and decreased body weight gain in normal pups at less than half of the clinical recommended doses. Sites of incomplete fetal ossification were increased in rats at approximately 3 times the clinical dose in vertebral (cervical, thoracic, lumbar), skull, and sternebral bone.
Both total and ionized calcium decreased in pregnant rats at approximately 4 times the clinical recommended dose, resulting in delays and failures of delivery. Maternotoxicty (late pregnancy deaths) also occurred in rats treated at approximately 4 times the clinical dose for varying periods of time (from only during pre-mating to treatment to only during early, middle or late pregnancy); these deaths were lessened but not eliminated by cessation of treatment. In studies with pregnant rats, oral alendronate doses of 2 mg/kg/day and above resulted in dystocia due to maternal hypocalcemia. Fetal weight was reduced in rats at maternal doses greater than 5 mg/kg/day. No teratogenic effects were seen in rats or rabbits at oral doses up to 25 and 35 mg/kg/day, respectively. Calcium supplementation either in the drinking water or by minipump may not ameliorate the hypocalcemia or prevent maternal and neonatal deaths due to delay in delivery; IV calcium supplementation prevented maternal, but not fetal deaths. There are no controlled data on fetal risk in humans or in human pregnancy.
Cholecalciferol:
Administration of high doses (greater than or equal to 10,000 international units/every other day) of ergocalciferol (vitamin D 2) to pregnant rabbits resulted in abortions and an increased incidence of fetal aortic stenosis. Administration of vitamin D 2 (40,000 international units/day) to pregnant rats resulted in neonatal death, decreased fetal weight, and impaired osteogenesis of long bones postnatally. There are no data available for cholecalciferol (vitamin D 3).
AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
AU, UK: Use should be avoided.
US: This drug should not be used during pregnancy unless the benefit outweighs the risk to the fetus.
AU TGA pregnancy category: B3
US FDA pregnancy category: C
Comment: There is theoretical risk of fetal harm, predominantly skeletal, if pregnancy occurs after completing a course of bisphosphonates therapy.
See references
