indication

For the reduction of the symptoms of muscle weakness and easy fatigability associated with the myasthenic syndrome of Eaton-Lambert. It is not indicated for treating myasthenia gravis.

pharmacology

Guanidine apparently acts by enhancing the release of acetylcholine following a nerve impulse. It also appears to slow the rates of depolarization and repolarization of muscle cell membranes.

toxicity

LD₅₀ = 475 mg/kg (oral, rat). Can cause severe gastrointestinal symptoms (nausea, vomiting and diarrhea), bone marrow suppression, renal insufficiency and other hematologic abnormalities (anemia, leucopenia). Severe guanidine intoxication is characterized by nervous hyperirritability, fibrillary tremors and convulsive contractions of muscle, salivation, vomiting, diarrhea, hypoglycemia, and circulatory disturbances.

biotransformation

Not metabolized.

absorption

Rapidly absorbed and distributed

half life

7-8 hours