PRYIDOSTIGMINE BROMIDE

INDICATION Pyridostigmine bromide oral solution USP is useful in the treatment of myasthenia gravis.

DOSAGE AND ADMINISTRATION Pyridostigmine bromide oral solution is available in the following dosage form: Oral Solution raspberry-flavored, containing 60 mg pyridostigmine bromide per teaspoonful (5 mL). This form permits accurate dosage adjustment for children and "brittle" myasthenic patients who require fractions of 60 mg doses. It is more easily swallowed, especially in the morning, by patients with bulbar involvement.

CONTRAINDICATIONS Pyridostigmine bromide oral solution is 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 underdosage, it can also be indicative of overdosage. As is true of all cholinergic drugs, overdosage of pyridostigmine bromide oral solution 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 oral solution 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

ADVERSE REACTIONS The side effects of pyridostigmine bromide oral solution 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 APNAR PHARMA LP at 1-855-642-2594 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

USE IN PREGNANCY The safety of pyridostigmine bromide oral solution during pregnancy or lactation in humans has not been established. Therefore, use of pyridostigmine bromide oral solution in women who may become pregnant requires weighing the drug's potential benefits against its possible hazards to mother and child.