Pyridostigmine Bromide

Pyridostigmine Bromide is indicated in-

• Myasthenia gravis
• Paralytic ileus
• Postoperative urinary retention

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 significant respects; for example, Pyridostigmine is characterized by a longer duration of action and fewer gastrointestinal side effects.

Adults: Doses of 60 to 120 mg (1 or 2 tablets) by mouth are given at intervals throughout the day when maximum strength is needed (for example on rising and before mealtimes). The usual duration of action of a dose is three to four hours in the daytime but a longer effect (six hours) is often obtained with a dose taken on retiring for bed. The total daily dose is usually in the range of 5-20 tablets but some patients may require doses higher than these.

Newborn Infants: The dosage requirements of Pyridostigmine range from 5-10 mg orally every four hours, given 30-60 minutes before feeding. Treatment is not usually required beyond eight weeks of age except in the rare conditions of congenital and familial infantile myasthenia.

Older Children: Children under 6 years old should receive an initial dose of half a tablet (30 mg) of Pyridostigmine, children 6-12 years old should receive one tablet (60 mg). Dosage should be increased gradually, in increments of 15-30 mg daily, until maximum improvement is obtained. Total daily requirements are usually in the range of 30-360 mg by mouth.

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 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.

The safety of Pyridostigmine during pregnancy or lactation has not been established.

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.

Drugs used in Myasthenia Gravis

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