In vitro teratogenicity of acetylsalicylic acid on rat embryos: studies with various culture conditions.

Rat embryos taken at day 9.5 of gestation were exposed in vitro to acetylsalicylic acid (aspirin) using various culture conditions. It was observed that embryos were sensitive to aspirin emulsified in olive oil at concentrations greater than or equal to 150 micrograms/ml. Between 43% and 66% of the embryos exhibited multiple malformations depending on the culture medium, 100% homologous rat serum or Waymouth medium supplemented with 50% rat serum, respectively. At concentrations greater than or equal to 400 micrograms/ml aspirin induced further toxic effects on embryo growth and differentiation. When gelatin was used as the drug-delivery system, aspirin at concentrations of greater than or equal to 150 micrograms/ml induced some malformations (mainly irregular somite shapes) in 57% of the embryos cultured in Waymouth medium, but in only 13% of the embryos grown in 100% serum. At concentrations which were greater than or equal to 400 micrograms/ml aspirin induced dysmorphogenic effects in all embryos, without any concomittant toxicity.