title: Plasma pyridostigmine levels in myasthenia gravis.
abstract: Plasma concentrations of pyridostigmine were measured after oral administration in 16 patients with myasthenia gravis. The levels varied greatly among both well- and poorly controlled patients, but were usually higher in the latter group. Absorption of the drug appears to be erratic; its clearance from the plasma is slow and its metabolism could involve an enterohepatic circulation. Drugs such as methylcellulose may prevent absorption. Three poorly controlled patients were studied on a high-dose alternate-day steroid regimen, and a marked decrease in pyridostigmine bioavailability on the same dose of drug was observed in all three. No such changes were demonstrated in a volunteer group taking a lower dose of steroids.
mesh_terms: D001682:Biological Availability; D006801:Humans; D009157:Myasthenia Gravis / Q000097:blood / Q000188:drug therapy*; D011239:Prednisolone / Q000627:therapeutic use; D011729:Pyridostigmine Bromide / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*
chemical_list: D011239:Prednisolone; D011729:Pyridostigmine Bromide