International Association Against Painful Experiments on Animals

101 Misleading results from Vivisection Animal Experiments

61: Pethidine Addiction

On the basis of experiments with dogs, the narcotic analgesic pethidine was once thought to be non-addictive in people.(1) The side effect was not anticipated because pethidine is metabolised, or broken down, much more quickly in dogs resulting in less exposure to the drug. In fact, dogs metabolise pethidine more than 6 times faster than people.(2)

Such differences in metabolism are the rule rather than the exception (2,3) and according to Miles Weatherall, former Director of the Wellcome Research Laboratories, "every species has its own metabolic pattern, and no two species are likely to metabolise a drug identically".(4)


1) B.Brodie, Pharmacologist, 1964, vol.6, 12-26.
2) R.Levine, Pharmacology: Drug Actions & Reactions (Little, Brown & Co.,1978)
3) G.Zbinden, Advances in Pharmacology, 1963, vol.2, 1-112.
4) M.Weatherall, Nature, 1982, April 1, 387-390.

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