What happens during paradoxical reaction to butorphanol?
There are many ways in which butorphanol can cause problems. If it is given with a narcotic agonist, butorphanol may precipitate withdrawals due to the receptors it it binds to (will talk about this in the next paragraph). By itself, in higher doses, it can cause delerium, hallucinations and dysphoria. Again, this has to do with the receptors it binds to. But if you are talking about Paradoxical reactions, then this is purely because of its actions at the Kappa receptor. There is evidence that has been shown that with mixed Kappa agonist-Mu antagonist drugs (like Butorphanol, Nubain, Fortral), they can sometimes worsen pain at lower doses. For example, 5mg of Nalbuphine (Nubain) can cause profound anti-analgesia in men but will produce pain relief in higher doses like 20mg. This is very common (but by no means unique) in drugs that act solely at the Kappa opioid receptor to produce pain relief. In addition, they also exhibit gender polymorphisms (they affect Men and Women differently).
