Cyclandelate and flunarizine, two vasoactive Ca2+ channel or Ca2+ overload blockers have been compared with respect to their in vivo action on field potentials recorded from the depths of the brain in freely moving rats. Whereas cyclandelate showed a dose dependent rapid onset of action in the range of 15 to 120 mg/kg i.p., flunarizine only induced weak effects very slowly, not reaching statistical relevance before the fourth hour after the injection (0.1 to 1.6 mg/kg). Even then no clear dose dependence could be recognized for flunarizine. With respect to the frequency content of the recorded signals a rather close similarity between both drugs could be seen. Comparison of the drug effects to our reference data base of more than 80 compounds revealed a close relationship to memantine, an antiparkinson drug, suspected to act on the NMDA (N-methyl-d-aspartate) receptor-ionophor complex controlling Ca2+ fluxes. There is some indication that cyclandelate might also act in a similar way at the molecular level.