Armodafinil

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Cat Number

API0232131

CAS Number

112111-43-0

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Product Detail Description Scientific Support Customer Q&A

CAS Number

112111-43-0

EINECS

682-508-8

Storage

Store at room temperature

Synonyms

(R)-Modafinil; CEP-10953; armodafinilo; Modafinil, (r)-; 2-[(R)-(Diphenylmethyl)sulfinyl]acetamide

Molecular Formula

C15H15NO2S

Molecular Weight

273.4

Smiles

C1=CC=C(C=C1)C(C2=CC=CC=C2)[S@](=O)CC(=O)N

Appearance

White to off-white crystalline powder

Melting Point

156-158°C

Boiling Point

559.1±50.0°C at 760 mmHg (Predicted)

Relative Density

1.283

General Description

Armodafinil is the (R)-enantiomer of modafinil, a wakefulness-promoting agent structurally unrelated to sympathomimetic amines. It is a racemate-free compound consisting of a single stereoisomer with a benzhydryl sulfinyl group. The (R)-enantiomer has a longer plasma half-life than the (S)-form and is responsible for most of the pharmacological activity of racemic modafinil.

Mechanism of Action

The exact mechanism is incompletely understood, but armodafinil activates orexin (hypocretin) neurons in the hypothalamus and increases histamine, norepinephrine, dopamine, and serotonin release. It binds to the dopamine transporter (DAT) but with a different binding site and lower potency than classical stimulants. Unlike amphetamines, it does not cause significant euphoria or dependence, likely due to its indirect and regional effects on dopaminergic pathways.

Application

Armodafinil is indicated to improve wakefulness in adults with excessive sleepiness associated with narcolepsy, obstructive sleep apnea (as adjunct to continuous positive airway pressure), and shift work disorder. It does not cure these conditions but improves functional status. The single-isomer formulation provides a more prolonged and consistent effect throughout the day compared to racemic modafinil.

In a phase 3 double‑blind trial (328 patients with high‑grade glioma and moderate‑to‑severe fatigue), armodafinil 150 mg, 250 mg, or placebo for 8 weeks showed no difference in the proportion achieving clinically meaningful fatigue reduction (28%, 28%, and 30%, respectively). Corticosteroid users had less global fatigue improvement than nonusers. Insomnia was reported in more patients on 250 mg armodafinil (7 vs. 2). Armodafinil did not reduce cancer‑related fatigue in this population, failing to support its use for this indication.

Fig. 1 CONSORT Diagram. (Porter AB, et al., 2022)

References

Porter AB, et al. Efficacy of Treatment With Armodafinil for Cancer-Related Fatigue in Patients With High-grade Glioma: A Phase 3 Randomized Clinical Trial. JAMA Oncol. 2022;8(2):259-267.

Does Armodafinil require protection from light during storage?

Yes, it is photosensitive. UV light can cause photodegradation and discoloration. Store in light-resistant containers, preferably amber glass.

What is the recommended storage temperature for Armodafinil?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can soften the powder and accelerate racemization.

Is Armodafinil stable under high-humidity conditions?

It is not hygroscopic and shows good stability. However, store in tightly sealed containers to prevent any potential moisture absorption.

How is the impurity modafinil (the racemic mixture or R-enantiomer degradation) monitored?

We use chiral HPLC to quantify the R-enantiomer purity and monitor for the formation of the S-enantiomer or related impurities during stability.