Investigation into the effects of ethinylestradiol, levonorgestrel and norethisterone on direct and total bilirubin of Wistar albino rats (Rattus rattus)
Some oral contraceptives namely Microgynon a combined pill (0.15mg levonorgestrel and 0.03mg ethinylestradiol), Primolut -N a mini pill (5mg norethisterone) and Postinor a post coital pill (0.75mg levonorgestrel)were analysed for their in vivo effects on rat plasma direct and total bilirubin. The in vivo effects of the oral contraceptives on rat plasma direct bilirubin showed that the drugs increased the direct bilirubin levels. The effect of the drugs on the directbilirubin levels were also time dependent and dose dependent with the highest increase obtained at 24 hours duration while the lowest increase occurred at 2 hours.Microgynon showed the highest increase (6.88 ± 0.00 vs control 3.19 ± 0.00 μmol/l) (p< 0.05) followed by Primolut–N (4.92 ± 0.00 vs control3.19 ± 0.00 μmol/l). The in-vivo effects of the oral contraceptives on rat plasma total bilirubin showed that the drugs increased the total bilirubin levelsin a concentration dependent manner. The effect of the drugs on the total bilirubin were also time dependent with the highest increase obtained at 24 hours while the lowest increase occurred at 2 hours duration. Microgynon showed the highest increase (18.31 ± 0.00 vs control 7.40 ± 1.85 μmol/l). It was observed from this study that most women do not undergo liver function test as part of their medical examination before these medicines are prescribed to them. Since these drugs increased the bilirubin levels, it is suggested that a thorough medical checkup that includes liver function tests be undergone before taking these oral contraceptives. It is also recommended that medical examination be done every twenty four weeks.
Keywords: Bilirubin, contraceptive, ethinylestradiol, levonorgestrel, norethisterone