A peripherally restricted µ-opioid receptor antagonist
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Methylnaltrexone (bromide)

Item No. 24072

Product Insert (PDF)Safety Data Sheet (SDS) (PDF)
Technical Information
Formal Name
17-(cyclopropylmethyl)-4,5α-epoxy-3,14-dihydroxy-17-methyl-6-oxo-morphinanium, monobromide
CAS Number
73232-52-7
Synonyms
  • MRZ 2663BR
  • Naltrexone methylbromide
Molecular Formula
C21H26NO4 • Br
Formula Weight
436.3
Purity
≥95%
Formulation
A crystalline solid
Solubility(Learn about Variance in Solubility)
PBS (pH 7.2): 10 mg/ml
SMILES
O[C@]12[C@]3(CC[N@+](CC4CC4)(C)[C@@H]2C5)[C@](OC6=C3C5=CC=C6O)([H])C(CC1)=O.[Br-]
InChi Code
InChI=1S/C21H25NO4.BrH/c1-22(11-12-2-3-12)9-8-20-17-13-4-5-14(23)18(17)26-19(20)15(24)6-7-21(20,25)16(22)10-13;/h4-5,12,16,19,25H,2-3,6-11H2,1H3;1H/t16-,19+,20+,21-,22+;/m1./s1
InChi Key
IFGIYSGOEZJNBE-LHJYHSJWSA-N
Shipping & Storage Information
Storage
-20°C
Shipping
Room temperature in continental US; may vary elsewhere
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    1 mg

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    Product Description

    Methylnaltrexone is a quaternary positively-charged form of naltrexone (Item No. 15520) that does not cross the blood brain barrier. It is a peripherally restricted µ-opioid receptor antagonist with a Ki value of 10 nM for human recombinant receptors expressed in CHO-K1 cells and IC50 values of 130.7 and 0.43 nM in rat brain membranes prepared with sodium chloride or water, respectively.1 Methylnaltrexone is selective for µ-opioid receptors over δ- and κ-opioid receptors (Kis = 630.95 and 31.62 nM, respectively). It inhibits contractions evoked by electrical field stimulation (EFS) in ileum isolated from morphine-naïve guinea pigs and dose-dependently decreases spontaneous mechanical activity in ileum isolated from morphine-treated guinea pigs when administered at doses of 1 and 10 µM.2 It does not inhibit heroin self-administration in rats and does not induce withdrawal syndrome in morphine-dependent rhesus monkeys when administered at doses up to 32 mg/kg.1,3 Formulations containing methylnaltrexone have been used in the treatment of opioid-induced constipation.

    WARNING This product is not for human or veterinary use.

    References & Product Citations
    Product Description References

    1. Valentino, R.J., Katz, J.L., Medzihradsky, F., et al. Receptor binding, antagonist, and withdrawal precipitating properties of opiate antagonists. Life Sci. 32(25), 2887-2896 (1983).

    2. Beattie, D.T., Cheruvu, M., Mai, N., et al. The in vitro pharmacology of the peripherally restricted opioid receptor antagonists, alvimopan, ADL 08-0011 and methylnaltrexone. Naunyn Schmiedebergs Arch. Pharmacol. 375(3), 205-220 (2007).

    3. Koob, G.F., Pettit, H.O., Ettenberg, A., et al. Effects of opiate antagonists and their quaternary derivatives on heroin self-administration in the rat. J. Pharm. Exp. Ther. 229(2), 481-486 (1984).