Safinamide mesylate
[CAS 202825-46-5]

Identification

• Classification: Biochemical >> Inhibitor >> Metabolism >> MAO inhibitor
• Name: Safinamide mesylate
• Synonyms: (S)-2-[[4-[(3-Fluorobenzyl)oxy]benzyl]amino]propanamide methanesulfonate
• Molecular Formula: C₁₇H₁₉FN₂O₂.CH₄O₃S
• Molecular Weight: 398.45
• CAS Registry Number: 202825-46-5
• EC Number: 606-485-0
• SMILES: C[C@@H](C(=O)N)NCC1=CC=C(C=C1)OCC2=CC(=CC=C2)F.CS(=O)(=O)O

Safety Data

• Hazard Symbols: GHS05;GHS06;GHS09 Danger
• Risk Statements: H301-H318-H400
• Safety Statements: P264-P264+P265-P270-P273-P280-P301+P316-P305+P354+P338-P317-P321-P330-P391-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Serious eye damage	Eye Dam.	1	H318
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2	H319
Reproductive toxicity	Repr.	2	H361
Acute toxicity	Acute Tox.	4	H332
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H312
Skin irritation	Skin Irrit.	2	H315

Discovery and Applications

Safinamide mesylate is the mesylate salt form of safinamide, a small-molecule drug used in the treatment of Parkinson’s disease. It functions as an antiparkinsonian agent with a dual mechanism of action, acting both as a reversible monoamine oxidase B (MAO-B) inhibitor and as a modulator of abnormal glutamate release. The mesylate (methanesulfonate) salt improves the compound’s stability and pharmaceutical formulation properties for oral administration.

Safinamide was developed through medicinal chemistry programs aimed at improving symptomatic control of Parkinson’s disease beyond dopamine replacement therapy. Parkinson’s disease is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra, leading to reduced dopamine levels in the striatum. Traditional treatments such as levodopa restore dopamine levels, but long-term use is associated with motor fluctuations and dyskinesias. Safinamide was designed to provide adjunctive therapy by enhancing dopaminergic signaling while also targeting non-dopaminergic mechanisms.

The primary pharmacological action of safinamide is selective, reversible inhibition of monoamine oxidase B. MAO-B is an enzyme responsible for the breakdown of dopamine in the brain. By inhibiting MAO-B, safinamide increases extracellular dopamine levels in the striatum, thereby improving motor symptoms in Parkinson’s disease. Unlike irreversible MAO inhibitors, safinamide binds reversibly, which allows for more controlled pharmacological effects.

In addition to MAO-B inhibition, safinamide has been shown to modulate voltage-gated sodium channels and reduce excessive glutamate release. This secondary mechanism is believed to contribute to its therapeutic effects on motor fluctuations and possibly on non-motor symptoms. Excessive glutamatergic activity has been implicated in excitotoxicity and motor complications in Parkinson’s disease, and modulation of this pathway provides an additional therapeutic benefit.

The discovery of safinamide involved screening and optimization of compounds that could affect both dopaminergic and glutamatergic neurotransmission. The goal was to develop a multifunctional drug capable of addressing multiple pathological mechanisms in Parkinson’s disease. Structural modifications led to a molecule with appropriate central nervous system penetration, enzymatic selectivity, and pharmacokinetic properties suitable for once-daily oral dosing.

Structurally, safinamide contains an aromatic core linked to an amide side chain and a fluorinated substituent that contributes to its binding affinity and metabolic stability. The mesylate salt form enhances its crystalline stability and solubility, which are important for consistent absorption and formulation in tablet form.

Clinically, safinamide mesylate is used as an add-on therapy to levodopa in patients with Parkinson’s disease experiencing “off” episodes, which are periods of reduced motor control due to fluctuations in levodopa effectiveness. By increasing dopaminergic tone and modulating glutamate activity, safinamide helps extend “on” periods when motor symptoms are better controlled.

Pharmacokinetically, safinamide is well absorbed after oral administration and undergoes hepatic metabolism, primarily through non-CYP enzymatic pathways, which reduces the potential for drug–drug interactions compared with some other antiparkinsonian agents. Its metabolites are eliminated mainly via renal excretion.

Adverse effects associated with safinamide include dyskinesia, insomnia, nausea, and headache. These effects are generally related to increased dopaminergic activity and are typically manageable through dose adjustment or concomitant therapy modification.

Overall, safinamide mesylate is a multifunctional antiparkinsonian drug that combines reversible MAO-B inhibition with modulation of glutamatergic transmission. Its development reflects a modern approach to Parkinson’s disease therapy, targeting both dopaminergic deficiency and downstream neurochemical dysregulation to improve motor symptom control in patients receiving levodopa therapy.

References

2026. Development and Evaluation of Chitosan-Safinamide Mesylate Nanoparticles for the Management of Parkinson’s Disease. BioNanoScience.
DOI: 10.1007/s12668-025-02347-x

2024. A novel stability-indicating chromatographic quantification of the antiparkinsonian drug safinamide in its pharmaceutical formulation employing HPTLC densitometry and ion-pair HPLC–DAD. BMC Chemistry.
DOI: 10.1186/s13065-024-01315-y

2020. A combined theoretical and experimental study on the structure, vibrational, and electronic properties of antiparkinsonian drug safinamide. SN Applied Sciences.
DOI: 10.1007/s42452-020-03661-7