Pyridostigmine Bromide

INDICATIONS AND USAGE Pyridostigmine bromide tablets are useful in the treatment of myasthenia gravis.

DOSAGE AND ADMINISTRATION Pyridostigmine bromide tablets, USP are available in following dosage form: Conventional Tablets each containing 30 mg pyridostigmine bromide. Dosage The size and frequency of the dosage must be adjusted to the needs of the individual patient. Conventional Tablets The average dose is twenty 30 mg tablets, spaced to provide maximum relief when maximum strength is needed. In severe cases as many as 50 tablets a day may be required, while in mild cases two to twelve tablets a day may suffice. NOTE: For information on a diagnostic test for myasthenia gravis, and for the evaluation and stabilization of therapy, please see product literature on Tensilon (edrophonium chloride).

CONTRAINDICATIONS Pyridostigmine bromide tablets are contraindicated in mechanical intestinal or urinary obstruction, and particular caution should be used in its administration to patients with bronchial asthma. Care should be observed in the use of atropine for counteracting side effects, as discussed below.

WARNINGS Although failure of patients to show clinical improvement may reflect under dosage, it can also be indicative of overdosage. As is true of all cholinergic drugs, overdosage of pyridostigmine bromide may result in cholinergic crisis, a state characterized by increasing muscle weakness which, through involvement of the muscles of respiration, may lead to death. Myasthenic crisis due to an increase in the severity of the disease is also accompanied by extreme muscle weakness, and thus may be difficult to distinguish from cholinergic crisis on a symptomatic basis. Such differentiation is extremely important, since increases in doses of pyridostigmine bromide or other drugs of this class in the presence of cholinergic crisis or of a refractory or "insensitive" state could have grave consequences. Osserman and Genkins 1 indicate that the differential diagnosis of the two types of crisis may require the use of Tensilon TM (edrophonium chloride) as well as clinical judgment. The treatment of the two conditions obviously differs radically. Whereas the presence of myasthenic crisis suggests the need for more intensive anticholinesterase therapy, the diagnosis of cholinergic crisis, according to Osserman and Genkins 1 , calls for the prompt withdrawal of all drugs of this type. The immediate use of atropine in cholinergic crisis is also recommended. Atropine may also be used to abolish or obtund gastrointestinal side effects or other muscarinic reactions; but such use, by masking signs of overdosage, can lead to inadvertent induction of cholinergic crisis. For detailed information on the management of patients with myasthenia gravis, the physician is referred to one of the excellent reviews such as those by Osserman and Genkins 2 , Grob 3 or Schwab 4,5 Usage in Pregnancy The safety of pyridostigmine bromide tablets during pregnancy or lactation in humans has not been established. Therefore, use of pyridostigmine bromide tablets in women who may become pregnant requires weighing the drug's potential benefits against its possible hazards to mother and child.

ADVERSE REACTIONS The side effects of pyridostigmine bromide tablets are most commonly related to overdosage and generally are of two varieties, muscarinic and nicotinic. Among those in the former group are nausea, vomiting, diarrhea, abdominal cramps, increased peristalsis, increased salivation, increased bronchial secretions, miosis and diaphoresis. Nicotinic side effects are comprised chiefly of muscle cramps, fasciculation and weakness. Muscarinic side effects can usually be counteracted by atropine, but for reasons shown in the preceding section the expedient is not without danger. As with any compound containing the bromide radical, a skin rash may be seen in an occasional patient. Such reactions usually subside promptly upon discontinuance of the medication. To report SUSPECTED ADVERSE REACTIONS, contact FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.