<prompt> Botulinum toxin acts by:Presynaptic release of acetyl cholinePresynaptic inhibition of release of acetylcholineGABA mimeticGABA antagonist  <response>: Ans.b Presynaptic inhibition of release of acetylcholineRef Katzung 10th ed. Ch 27 Botulinum toxin is a neuromascular blocking agent which act at neuromascular junction by blocking the presynaptic release of Ach vesicles. Doing so, it reduces spasticity in a variety of neurologic conditions ie, spasmolytics. NOTE: Neuromuscular blocking drugs interfere with transmission at the neuromuscular end plate and lack central nervous system activity. Also KnowMOA of drugs and their siteDrugSite of ActionMoaLocal anestheticsNerve axonsBlock Na channelsHemicho- liniumAt cholinergic nerve terminalBlocks uptake of choline and slows synthesisVesamicolCholinergic terminal vesiclePrevents storage, depletesReserpineAdrenergic terminal vesiclePrevents storage, depletesTyramine, Ampheta- mineAdrenergic nerve terminalsPromote transmitter releaseBethanecholReceptors, parasympathetic effector cells smooth muscle, glandsBinds and activates muscarinic receptorsAtropineReceptors, parasympathetic effector cellsBinds muscarinic receptors; prevents activatio 