Indomethacin toxicity in rats

Robert C. Newton Robert_C._Newton at
Thu Sep 21 09:06:34 EST 1995

> Indomethacin adnimistered to Lewis, BN, and F1(Lewis x BN) rats resulted
> in  mortality in 4-5 days. Indomethacin was prepared freshly in sodium
> carbonate  buffer and administered i.p. or by gavage, 0.5 or 1 mg per
> rat. The  recommended dose in the literature is 1 mg/rat/day. I haven't
> come across any  report on toxicity at this dosage. It woul be of
> immense help if someone could  share his/her experience and suggest
> alternate means to inhibit the  cyclooxygenase pathway in rats.

I think you have missed in your dosing.  The correct oral dose should be 1
mg/kg/rat.  An oral dose of 1 mg in a 250g rat would give you a toxic dose of
4 mg/kg.  Rule of thumb is never exceed 3 mg/kg or you'll be guraanteed
toxicity.  A dose of 1 mg/kg is standard to maximally block CO activity
without toxicity.


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