How is Carbochol (carbamylcholine) as direct acting cholinergic agonist?

Ester of carbamic acid and poor substrate for acetylcholinesterase, positive charged quaternary amonium, biotransformed by other esterases, much slower rate, muscarinic effect and causes release of Epi by nicotinic action. admin intraocular solution/injection, high potency, no selectivity, long duration of action so rarely used therapeutically except in the eye. Used as miotic for treating glaucoma/ ophthalmic surgery