Primidone is an anticonvulsant agent and highly efficient, selective TRPM3 blocker IC50 of 0.6 uM and marked specificity for TRPM3. Primidone (3-5 uM) inhibits PregS-induced inward currents in electrophysiological recordings, Primidone (10 uM) also inhibits the omega pore-like currents evoked by coapplied PregS and clotrimazole. Primidone shows no effect on TRPA1, TRPM8, TRPM2, TRPC5, TRPC6 and P2X7 receptors. Primidone acts as an inhibitory allosteric modulator and suppresses TRPM3-dependent Ca2+ entry induced by thermal stimulation. Primidone blocks calcium signals in isolated rat dorsal root ganglia neurones and human TRPM3. Primidone attenuates the sensitivity of mice to chemical and thermal stimulation.
