Pyridostigmine Bromide

Pyridostigmine is useful in the treatment of myasthenia gravis.

Pyridostigmine tablet is an orally active cholinesterase inhibitor. Pyridostigmine inhibits the destruction of acetylcholine by cholinesterase and thereby permits freer transmission of nerve impulses across the neuromuscular junction. Pyridostigmine is an analog of neostigmine, but differs from it in certain clinically signihcant respects; for example, Pyridostigmine is characterized by a longer duration of action and fewer gastrointestinal side effects.

The size and frequency of the dosage must be adjusted to the needs of the individual patient. The average dose is 10 tablets (600 mg) spaced to provide maximum relief when maximum strength is needed. In severe cases as many as 25 tablets (1500 mg) a day may be required, while in mild cases one to six tablets a day may sufhce. The interval between doses should be at least 6 hours.

A potential interaction between the antimalarial drug mefloquine and pyridostigmine bromide exists through a possible additive effect on the gastrointestinal tract. Theoretically, drugs such as dexpanthenol, which are converted to pantothenic acid in vivo, may have additive effects with pyridostigmine by increasing production of acetylcholine.

Pyridostigmine 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.

The side effects of Pyridostigmine are most commonly related to overdose and generally are of two varieties, muscarinic and nicotinic. Muscarinic side effects are nausea, vomiting, diarrhea, abdominal cramps, increased peristalsis movement, 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. As with any compound containing the bromide radical, a skin rash may be seen in an occasional patients. Such reactions usually subside promptly upon discontinuance of the medication.

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Pyridostigmine is mainly excreted unchanged by the kidney. Therefore, lower doses may be required in patients with renal disease, and treatment should be based on titration of drug dosage to effect.

Symptoms may include diarrhea; fainting; increased production of saliva; increased sweating; muscle weakness; nausea; small pupils; stomach cramps; trouble breathing; vision changes; vomiting; weakness.

Drugs used in Myasthenia Gravis.

Renal Impairment: Lower initial dose may be needed, titrate to desired effect.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Store in cool and dry place, protected from light. Keep out of children’s reach.