Name: Pyridostigmine (Mestinon)
Class: Anticholinesterase Agent: Carbamate (Quaternary Amine)
Mech.: Substrate for AChE. Competitive inhib. of interaction btwn ACh and AChE. Stim. postjxnl nicotinic (i.e., muscular) receptors.
Absorption: Oral adequate.
Metab.: Slowly hydrolyzed by AChE
Dist.: No CNS. Acts mostly at neuromusc sites. Some autonomic action.
Excretion, t½: Slowly hydrolyzed by AChE
Toxicity/S.E.s: Toxic doses first stim. then depress autonom. ganglia, NM jxns, and central sites. Dose too large ® skel. muscle weakness = cholinergic crisis. Too small ® muscle weakness = myasthenic weakness. Avoid in cases of asthma, coronary insufficiency, peptic ulcers.
Utility: Treat myasthenia gravis. Longer acting than neostigmine; used more freq.
Special Features: Non-selective. Stim. cholinergic receptors throughout CNS and PNS. Inhib. AChE and BuChE.