Pyridostigmine Bromide is an orally active, reversible cholinesterase inhibitor used as an active pharmaceutical ingredient in medicines for the management of myasthenia gravis. It is a quaternary ammonium carbamate derivative and is supplied as the bromide salt.
Pyridostigmine works by inhibiting the enzymatic breakdown of acetylcholine, thereby increasing acetylcholine availability at cholinergic synapses and facilitating transmission across the neuromuscular junction.
Pyridostigmine belongs to the cholinesterase inhibitor class. It is a reversible acetylcholinesterase/cholinesterase inhibitor acting predominantly in the peripheral nervous system.
Pyridostigmine reversibly inhibits cholinesterase and reduces the breakdown of acetylcholine. The resulting increase in acetylcholine facilitates transmission of nerve impulses across the neuromuscular junction.
Because pyridostigmine is a quaternary ammonium compound, it is primarily associated with peripheral cholinergic activity and does not significantly cross the blood-brain barrier.
Pyridostigmine Bromide is primarily used in pharmaceutical formulations for:
Pyridostigmine Bromide tablets are officially described for treatment of myasthenia gravis in U.S. labeling.
Pyridostigmine Bromide is described as a white or almost white, crystalline, deliquescent powder. It is very soluble in water and alcohol, slightly soluble in hexane, and practically insoluble in ether.
| Property | Value |
|---|---|
| Molecular Weight | 261.12 g/mol |
| Exact Mass | 260.01604 Da |
| H-Bond Donor Count | 0 |
| H-Bond Acceptor Count | 3 |
| Rotatable Bond Count | 2 |
| Topological Polar Surface Area | 33.4 Ų |
These calculated properties are reported by PubChem.
Pyridostigmine Bromide API can be characterized using:
Analytical testing should establish the identity, purity, assay and impurity profile of each API batch.
Quality control for Pyridostigmine Bromide should include:
The specific numerical acceptance limits should be taken from the applicable USP/registered API specification rather than using unsupported generic limits.
Pyridostigmine Bromide does not contain a stereogenic center in its standard chemical structure. Therefore, chiral purity is not normally a critical quality attribute for the API.
Pyridostigmine Bromide is a deliquescent material, so moisture exposure should be minimized. Appropriate storage should use a tightly closed container under controlled conditions established by the applicable API stability data.
Recommended handling:
Typical API documentation can include:
Pyridostigmine Bromide API manufacturing involves controlled synthesis, purification, isolation, drying and analytical testing. Particular attention should be given to salt identity, purity, moisture control and related substances because Pyridostigmine Bromide is hygroscopic/deliquescent.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 0.5% |