REVEX (nalmefene hydrochloride injection), an opioid antagonist, is a 6-methylene
analogue of naltrexone. The chemical structure is shown below:
Molecular Formula: C21H25NO3•HCl
Molecular Weight: 375.9, CAS # 58895-64-0
Chemical Name: 17-(Cyclopropylmethyl)-4,5a-epoxy-6-methylenemorphinan-3,14-diol,
Nalmefene hydrochloride is a white to off-white crystalline powder which is
freely soluble in water up to 130 mg/mL and slightly soluble in chloroform up
to 0.13 mg/mL, with a pKa of 7.6.
REVEX is available as a sterile solution for intravenous, intramuscular, and
subcutaneous administration in two concentrations, containing 100 µg or
1.0 mg of nalmefene free base per mL. The 100 µg/mL concentration contains
110.8 µg of nalmefene hydrochloride and the 1.0 mg/mL concentration contains
1.108 mg of nalmefene hydrochloride per mL. Both concentrations contain 9.0
mg of sodium chloride per mL and the pH is adjusted to 3.9 with hydrochloric
Concentrations and dosages of REVEX are expressed as the free base equivalent of nalmefene.
Last reviewed on RxList: 6/11/2012
This monograph has been modified to include the generic and brand name in many instances.