Evaluation of developmental toxicity and teratogenicity of diclofenac using Xenopus embryos

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) with analgesic and anti-pyretic properties. This compound is therefore used to treat pain, inflammatory disorders, and dysmenorrhea. Due to its multimodal mechanism of action and ability to penetrate placenta, diclofenac is known to have undesirable side effects including teratogenicity. However, limited data exist on its teratogenicity, and a detailed investigation regarding harmful effects of this drug during embryogenesis is warranted. Here, we analyzed the developmental toxic effects of diclofenac using Xenopus embryos according to the Frog Embryo Teratogenesis Assay-Xenopus (FETAX) protocol. Diclofenac treatment exerted a teratogenic effect on Xenopus embryos with a teratogenic index (TI) value of 2.64 TI; if this value is higher than 1.2, the cut-off value indicative of toxicity. In particular, mortality of embryos treated with diclofenac increased in a concentration-dependent manner and a broad spectrum of malformations such as shortening and kinking of the axis, abdominal bulging, and prominent blister formation, was observed. The shape and length of internal organs also differed compared to the control group embryos and show developmental retardation on histological label. However, the expression of major tissue-specific markers did not change when analyzed by reverse transcription-polymerase chain reaction (RT-PCR). In conclusion, diclofenac treatment can promote teratogenicity that results in morphological anomalies, but not disrupt the developmental tissue arrangement during Xenopus embryogenesis.