Plasma pyridostigmine levels in myasthenia gravis

• Published in: Neurology Vol. 31; no. 2; p. 145
• Main Authors: White, M C, De Silva, P, Havard, C W
• Format: Journal Article
• Language: English
• Published: United States 01.02.1981
• Subjects: Biological Availability; Humans; Myasthenia Gravis - blood; Myasthenia Gravis - drug therapy; Prednisolone - therapeutic use; Pyridostigmine Bromide - administration & dosage; Pyridostigmine Bromide - blood; Pyridostigmine Bromide - therapeutic use
• ISSN: 0028-3878
• DOI: 10.1212/wnl.31.2.145

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.