Interaction between local anesthetics and analeptic drugs.

Although clinicall undesirable, the fortuitous pharmacologic interactions between local anesthetic agents and analeptic drugs may be protective when large doses of both agents are used. Mice pretreated with procaine, lidocaine, and tetracaine had a lower incidence of seizures when convulsive doses of either nikethamide or doxapram hydrochloride were given intraperitoneally. Mortality was also decreased in the groups given nikethamide and was zero in the animals treated with doxapram. All animals treated with pentylenetetrazol convulsed and only lidocaine (also used as an anticonvulsant) was able to reduce mortality in this group. Of the local anesthetic agents, tetracaine afforded the least protection from death, whereas lidocaine seemed to be most effective.