Neostigmine Methylsulfate is a synthetic reversible acetylcholinesterase inhibitor and cholinergic pharmaceutical API. It increases the availability of acetylcholine by inhibiting its enzymatic breakdown and thereby enhances cholinergic transmission.
Neostigmine Methylsulfate is an important pharmaceutical form of neostigmine used in formulations associated with neuromuscular transmission, reversal of non-depolarizing neuromuscular blockade and other cholinergic applications.
Neostigmine Methylsulfate is a well-characterized anticholinesterase pharmaceutical API used in pharmaceutical formulation development, manufacturing, analytical testing and research involving cholinergic and neuromuscular pharmacology.
The API is chemically distinct from Neostigmine Bromide. Neostigmine Methylsulfate has the molecular formula C₁₃H₂₂N₂O₆S and molecular weight 334.39 g/mol.
CAS Number: 51-60-5
Molecular Formula: C₁₃H₂₂N₂O₆S
Molecular Weight: 334.39 g/mol
Chemical Name: 3-[(Dimethylcarbamoyl)oxy]-N,N,N-trimethylbenzenaminium methyl sulfate
Drug Class: Cholinesterase Inhibitor
Therapeutic Class: Anticholinesterase / Cholinergic Agent
Therapeutic Area: Neurology / Anesthesiology
Molecule Type: Synthetic Small Molecule
Synonyms: Neostigmine Methylsulfate, Neostigmine Methylsulphate, Neostigmine Methosulfate
USP and the International Pharmacopoeia identify the substance as CAS 51-60-5 with molecular formula C₁₃H₂₂N₂O₆S and molecular weight approximately 334.4 g/mol.
Neostigmine Methylsulfate acts as a reversible acetylcholinesterase inhibitor.
Its pharmacological activity includes:
Because neostigmine is a quaternary ammonium compound, its penetration into the central nervous system is limited.
Neostigmine Methylsulfate API is relevant to:
Neostigmine Methylsulfate increases acetylcholine concentration at the neuromuscular junction by inhibiting acetylcholinesterase.
This pharmacological action enhances neuromuscular transmission and makes the compound particularly relevant to pharmaceutical preparations used for the reversal of non-depolarizing neuromuscular blockade.
Neostigmine Methylsulfate belongs to the reversible cholinesterase inhibitor class.
By reducing enzymatic degradation of acetylcholine, it enhances the action of acetylcholine at cholinergic receptors. This mechanism is central to its pharmacological applications in neuromuscular and parasympathetic systems.
Neostigmine Methylsulfate is described as a white crystalline powder and is hygroscopic.
It is very soluble in water and freely soluble in ethanol. The International Pharmacopoeia also identifies it as a white crystalline powder and specifies storage in a tightly closed container protected from light.
A controlled Neostigmine Methylsulfate API manufacturing process may involve:
Typical Neostigmine Methylsulfate API testing may include:
The USP monograph includes identification and assay, while the Japanese Pharmacopoeia additionally specifies pH, melting point, loss on drying and residue on ignition.
Store Neostigmine Methylsulfate API in a tightly closed container protected from light and moisture.
The International Pharmacopoeia specifically recommends storage in a tightly closed container protected from light.
| Parameter | Specification |
|---|---|
| Appearance | White crystalline powder or crystals |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.1% |
| pH (1% Solution) | 3.0 – 5.0 |
| Individual Impurity | NMT 0.1% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.0% |
| Melting Point | 145 – 149°C |