A patient complains of muscle weakness it was reversed on administration of neostigmine, because

Refer katzung 11e p 105 neostigmine acts by inhibiting the enzyme acetylcholinesteresis This enzyme is involved in the degradation of acetylcholine, consequential neostigmine increases the synaptic level of acetylcholine. Muscle weakness can be improved with the stimulation of Nm receptors at muscle endplate due to increase the acetylcholine