DOSAGE AND ADMINISTRATION
The oral dose must be individualized according to the patient's response because the disease varies widely in its severity in different patients and because patients vary in their sensitivity to cholinergic drugs. Since the point of maximum therapeutic effectiveness with optimal muscle strength and no gastrointestinal disturbances is a highly critical one, the close supervision of a physician familiar with the disease is necessary.
Because its action is longer, administration of MYTELASE is necessary only every three or four hours, depending on the clinical response. Usually medication is not required throughout the night, so that the patient can sleep uninterruptedly.
For the patient with moderately severe myasthenia, from 5 mg to 25 mg of MYTELASE three or four times daily is an effective dose. In some patients a 5 mg dose is effective, whereas other patients require as much as from 50 mg to 75 mg per dose. The physician should start with a 5 mg dose, carefully observing the effect of the drug on the patient. The dosage may then be increased gradually to determine the effective and safe dose. The longer duration of action of MYTELASE makes it desirable to adjust dosage at intervals of one to two days to avoid drug accumulation and overdosage. (See OVERDOSAGE.)
In addition to individual variations in dosage requirements, the amount of cholinergic medication necessary to control symptoms may fluctuate in each patient, depending on his activity and the current status of the disease, including spontaneous remission. A few patients have required greater doses for adequate control of myasthenic symptoms, but increasing the dosage above 200 mg daily requires exacting supervision of a physician well aware of the signs and treatment of overdosage with cholinergic medication.
Edrophonium (Tensilon®) may be used to evaluate the adequacy of the maintenance dose of anti-cholinesterase medication. Two mg edrophonium are administered intravenously one hour after the last anticholinesterase dose. A transient increase in strength occurring about 30 seconds later and lasting 3 to 5 minutes indicates insufficient maintenance dose. If the dose is adequate or excessive, no change or a transient decrease in strength will occur, sometimes accompanied by muscarinic symptoms.