Pilocarpine is an:

Ans. a. Active mioticRef: Goodman Gilman 13th ElPI 259Miosis: Contraction of pupil can be seen due to contraction of circular muscles (active miosis), due to M3 stimulation or it can be seen due to relaxation of radial muscles (passive miosis), due to al receptors block. Relaxation of radial muscles can cause miosis due to unopposed action of circular muscles. Thus, cholinergics like pilocarpine and physostigmine are active miotics, whereas alpha blockers like phentolamine and phenoxybenzamine are passive miotics.Mydriasis: Relaxation of pupil can be seen due to contraction of radial muscles (active mydriasis) due to al receptors stimulation or due to relaxation of circular muscles (passive mydriasis) due to M3 blockers. Relaxation of circular muscles cause mydriasis due to unopposed action of radial muscles. Thus, sympathomimetics like phenylephrine and ephedrine are active mydriatics, whereas anticholinergics like atropine, tropicamide and cyclopentolate are passive mydriatics.MioticsMydriaticsActivePassiveActivePassivePilocarpinePhysostigminePhentolaminePhenoxybenzaminePhenylephrineEphedrineAtropineTropicamide