Pyridostigmine Bromide
Brand names: pyridostigmine bromide, Pyridostigmine Bromide, Pryidostigmine Bromide, PRYIDOSTIGMINE BROMIDE, Mestinon, Pyridostigmine bromide, Regonol
Boxed warning
WARNING: RISKS WITH IMPROPER USE OF PYRIDOSTIGMINE BROMIDE After Exposure to Soman, Use Atropine and Pralidoxime Pyridostigmine bromide is for use as a pretreatment for exposure to soman nerve agent. Pyridostigmine bromide alone will not protect against exposure to soman. The efficacy of pyridostigmine bromide is dependent upon the rapid use of atropine and pralidoxime (2-PAM) after soman exposure [see Dosage and Administration (2.1) and Warnings and Precautions (5.1) ]. Always Use Protective Garment(s) Primary protection against exposure to chemical nerve agents is the wearing of protective garments including masks, hoods, and overgarments designed specifically for this use. Individuals must not rely solely upon pretreatment with pyridostigmine bromide and on the antidotes atropine and pralidoxime (2-PAM) to provide complete protection from poisoning by soman nerve agent [see Dosage and Administration (2.1) ] . Pyridostigmine Bromide as Pretreatment Only If pyridostigmine bromide is taken immediately before exposure (e.g., when the gas attack alarm is given) or at the same time as poisoning by soman, it is not expected to be effective and may exacerbate the effects of a sub-lethal exposure to soman. Do not take pyridostigmine bromide after exposure to soman [see Clinical Pharmacology (12.2) ]. FOR MILITARY MEDICAL USE ONLY WARNING: RISKS WITH IMPROPER USE OF PYRIDOSTIGMINE BROMIDE See full prescribing information for complete boxed warning. After Exposure to Soman, Use Atropine and Pralidoxime Pyridostigmine bromide is for use as a pretreatment for exposure to soman nerve agent. Pyridostigmine bromide alone will not protect against exposure to soman. The efficacy of pyridostigmine bromide is dependent upon the rapid use of atropine and pralidoxime (2-PAM) after soman exposure. ( 2.1 , 5.1 ) Always Use Protective Garment(s) Primary protection against exposure to chemical nerve agents is the wearing of protective garments. ( 2.1 , 5.1 ) Pyridostigmine Bromide as Pretreatment Only If taken immediately before soman exposure (e.g., when the gas attack alarm is given) or at the same time as poisoning by soman, it is not expected to be effective and may exacerbate the effects of a sub-lethal exposure to soman. Do not take pyridostigmine bromide after exposure to soman. ( 2.1 , 12.2 )
Warnings
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 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 ®# (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 during pregnancy or lactation in humans has not been established. Therefore, use of pyridostigmine bromide in women who may become pregnant requires weighing the drug's potential benefits against its possible hazards to mother and child.
Contraindications
CONTRAINDICATIONS Pyridostigmine bromide tablets, USP 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.
Overdose
10 OVERDOSAGE Overdosage of pyridostigmine bromide may result in cholinergic crisis, a state characterized by increasing muscle weakness that, through involvement of the muscles of respiration, may lead to death. Overdosage with pyridostigmine bromide must be differentiated from the acute manifestations of nerve agent poisoning, which may also be characterized by a cholinergic crisis. Extremely high doses of pyridostigmine bromide may also produce central nervous system (CNS) symptoms of agitation, restlessness, confusion, visual hallucinations, and paranoid delusions. Electrolyte abnormalities, possibly resulting from high serum bromide concentrations, also have been reported. Death may result from cardiac arrest or respiratory paralysis and pulmonary edema. In the treatment of pyridostigmine bromide overdosage, maintaining adequate respiration is of primary importance. Tracheostomy, bronchial aspiration, and postural drainage may be required to maintain an adequate airway; respiration can be assisted mechanically if required. Supplemental oxygen may be necessary. Pyridostigmine bromide should be discontinued immediately and 1 mg to 4 mg of atropine sulfate administered intravenously. Additional doses of atropine may be given every 5 to 30 minutes as needed to control muscarinic symptoms. Atropine overdosage should be avoided, as tenacious secretions and bronchial plugs may result. It should be kept in mind that unlike muscarinic effects, the skeletal muscle effects and consequent respiratory paralysis (nicotinic effects), which can occur following pyridostigmine overdosage, are not alleviated by atropine.
Drug interactions
7 DRUG INTERACTIONS Mefloquine: Additive effect on gastrointestinal tract and atrial rate. ( 7.1 ) Anticholinesterase drugs for glaucoma treatment: Additive effect. ( 7.2 ) Narcotics: Exacerbation of bradycardia possible. ( 7.3 ) Depolarizing neuromuscular blocking agents: Increased effect. ( 7.4 ) Non-depolarizing neuromuscular blocking agents: Dose may need to be increased. ( 7.4 ) Aminoglycoside antibiotics, local and some general anesthetics, antiarrhythmic agents, and other drugs that interfere with neuromuscular transmission should be used cautiously, if at all. ( 7.4 ) Drugs converted to pantothenic acid (e.g., dexpanthenol): Additive effect. ( 7.5 ) 7.1 Mefloquine Concomitant use of mefloquine and pyridostigmine bromide may have additive effects on the gastrointestinal tract, the most common of which is loose bowels. Additive effects on the atrial rate may also occur with concomitant use of mefloquine and pyridostigmine bromide. 7.2 Other Anticholinesterase Drugs Concomitant use of anticholinesterase drugs used in the treatment of glaucoma and pyridostigmine bromide may have an additive effect that may cause or exacerbate problems with night vision. 7.3 Narcotics The bradycardia associated with the use of narcotics may exacerbate pyridostigmine-induced bradycardia. 7.4 Drugs that Interfere with Neuromuscular Transmission Particular caution should be observed in the administration of depolarizing neuromuscular blocking agents (e.g., succinylcholine) during surgery since the degree of neuromuscular blockade that ensues may be enhanced by previously administered pyridostigmine bromide. Doses of non-depolarizing neuromuscular blocking agents (e.g., pancuronium bromide) may need to be increased in patients previously administered pyridostigmine bromide. Atropine antagonizes the muscarinic effects of pyridostigmine bromide, and this interaction is utilized to counteract the muscarinic symptoms of pyridostigmine bromide toxicity. Anticholinesterase agents are sometimes effective in reversing neuromuscular block induced by aminoglycoside antibiotics. However, aminoglycoside antibiotics, local and some general anesthetics, antiarrhythmic agents, and other drugs that interfere with neuromuscular transmission should be used cautiously, if at all, during treatment with pyridostigmine bromide. 7.5 Drugs Converted to Pantothenic Acid Concomitant use of drugs that are converted to pantothenic acid in vivo (e.g., dexpanthenol) and pyridostigmine bromide may have additive effects by increasing production of acetylcholine.
Uses
INDICATIONS AND USAGE Pyridostigmine bromide tablets, USP are useful in the treatment of myasthenia gravis.
Dosage forms & strengths
DOSAGE AND ADMINISTRATION Pyridostigmine bromide tablets, USP is available as Conventional Tablets - each containing 60 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 ten 60 mg tablets, spaced to provide maximum relief when maximum strength is needed. In severe cases as many as 25 tablets a day may be required, while in mild cases one to six 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).
All identified pills
Side effects
ADVERSE REACTIONS The side effects of pyridostigmine bromide 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.