About Halothane Haloalkane derivative, Inhalation General Anesthetic. Mechanism of Action of Halothane Halothane will alter presynaptic activity and the release of neurotransmitters due to alterations in intracellular signaling. Halothane similarly inhibit non-NMDA and NMDA receptor-mediated excitatory postsynaptic currents in both cell types at low concentrations but preferentially blocked responses to exogenously applied AMPA at higher concentrations. Synaptically but not directly evoked action potentials in interneurons were inhibited by halothane. Indications for Halothane 1. Inhalational anaesthesia 2. Operations where blood-less field is required