Nalmefene Hydrochloride

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Cat Number

API0232111

CAS Number

58895-64-0

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Product Detail Description Scientific Support Customer Q&A

CAS Number

58895-64-0

EINECS

641-080-2

Storage

Store at room temperature

Synonyms

Nalmefene HCl; Revex; opvee; ZURNAI; JF-1 HYDROCHLORIDE; K7K69QC05X; DTXSID70891705

Molecular Formula

C21H26ClNO3

Molecular Weight

375.9

Smiles

C=C1CC[C@]2([C@H]3CC4=C5[C@]2([C@H]1OC5=C(C=C4)O)CCN3CC6CC6)O.Cl

Appearance

White to off-white solid

Melting Point

180-185°C

Boiling Point

507.9°C at 760 mmHg

General Description

Nalmefene hydrochloride is a pure opioid antagonist with a 6-methylene group replacing the 6-oxo group of naltrexone. The molecule is a derivative of naloxone with a cyclopropylmethyl substituent on the nitrogen and a methylene bridge at the 6-position. This structural modification increases oral bioavailability and prolongs the duration of action compared to naloxone.

Mechanism of Action

Nalmefene is a competitive antagonist at mu, delta, and kappa opioid receptors, with highest affinity for the mu receptor. It has no intrinsic agonist activity and can reverse all effects of opioid agonists, including respiratory depression, analgesia, and euphoria. Unlike naloxone, nalmefene has a longer plasma half-life (approximately 10-12 hours) and higher oral bioavailability, making it suitable for chronic oral use to reduce alcohol craving.

Application

Nalmefene is indicated for the management of alcohol dependence, reducing the number of heavy drinking days in patients with high-risk drinking levels. It is also used intravenously for the complete or partial reversal of opioid overdose, especially when the duration of action of the opioid is long (e.g., methadone).

In a double‑blind, placebo‑controlled crossover fMRI study of 18 non‑treatment‑seeking individuals with alcohol use disorder (high‑risk drinking), a single 18 mg dose of nalmefene reduced alcohol cue‑reactivity specifically in the ventral striatum (a key region of the mesolimbic reward system), but not in the dorsal striatum. Subjective craving measured after cue exposure was also significantly lower with nalmefene than placebo. The findings suggest that nalmefene exerts an anti‑craving effect by attenuating neural responses to alcohol cues in the ventral striatum.

Fig. 1 Comparison sum score of AUQ after fMRI cue-reactivity task between nalmefene and placebo. (Karl D, et al., 2021)

References

Karl D, et al. Nalmefene attenuates neural alcohol cue-reactivity in the ventral striatum and subjective alcohol craving in patients with alcohol use disorder. Psychopharmacology (Berl). 2021;238(8):2179-2189.

Does Nalmefene Hydrochloride require protection from light during long-term storage?

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

What is the recommended storage temperature for Nalmefene Hydrochloride?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate oxidative degradation of the cyclopropylmethyl group.

Is Nalmefene Hydrochloride stable in solution for injectable use?

Aqueous solutions are stable when protected from light and stored at room temperature for up to 24 hours.

How is the impurity nalmefene 6-keto reduction product (a metabolite) monitored?

This degradation product is quantified using a stability-indicating HPLC method, ensuring it remains within ICH qualification thresholds.