Naltrexone Chemical Structure

What is Naltrexone?

Naltrexone is an organic heteropentacyclic molecule that possesses competitive opioid antagonistic properties. It is a derivative of noroxymorphone. It is utilized in the treatment of opiate addiction and alcoholism as a method of preventing relapse. Naltrexone was first manufactured in 1965, and it wasn’t until 1984 that its use in medicine was legalized in the United States.

There are many other brand names under which naltrexone is now being sold or has been sold in the past, such as Adepend, Antaxone, Celupan, Depade, Nalorex, Narcoral, Nemexin, Nodict, Revia, Trexan, Vivitrex, and Vivitrol. It is also sold as Contrave, which is a combination of naltrexone and bupropion and was marketed with morphine (morphine/naltrexone) as Embeda.

Macsen Laboratories is the leading supplier of high-quality Naltrexone.
Name of Product Naltrexone
IUPAC Name (4R,4aS,7aR,12bS)-3-(cyclopropylmethyl)-4a,9-dihydroxy-2,4,5,6,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one
Synonyms ReVia; N-Cyclopropylmethylnoroxymorphone; Vivitrex; Vivitrol; Celupan; Nemexin
CAS No 16590-41-3
Molecular Formula C20H23NO4
Molecular Weight 341.4 g/mol
Pubchem CID 5360515
Pubchem SID 475523896

Chemical Properties

SR. No Criteria Limit/Specification
1 Appearance (Form) Crystalline Powder
2 Appearance (Colour) Off-white to light tan
3 Solubility Solubility of 100 mg/mL in water at 25 °C (as hydrochloride salt)
Soluble in ethanol
4 Melting Point 168-170 °C
5 Decomposition When heated to decomposition it emits toxic fumes of nitrogen oxides


  • The effectiveness of naltrexone in treating alcoholism has been demonstrated via extensive research. It has been found to decrease both the amount and frequency of ethanol use.
  • Naltrexone is prescribed for the treatment of blocking the effects of opioids taken exogenously to prevent relapse into opioid dependence following detoxification from opioids. It is utilized as part of a comprehensive drug misuse treatment programme (such as compliance monitoring, counseling, behavioral contract, lifestyle changes).

Side effects

The common side effects associated with the use of Naltrexone are-

  • Nausea
  • Gastrointestinal complaints such as diarrhea and abdominal cramping
  • Headache, dizziness, anxiety
  • Tiredness, trouble sleeping
  • Mild opiate withdrawal symptoms- abdominal cramps, restlessness, bone/joint pain, muscle aches, and runny nose

Some of the serious side effects include-

Naltrexone should not be administered to children and adolescents younger than 18 years of age, as well as individuals with severe hepatitis, liver failure, or recent opiate usage (typically 7–10 days).


Q. Does naltrexone make you lose weight?

The combination of bupropion and naltrexone is used in conjunction with a low-calorie diet and regular exercise to aid with weight loss and maintenance.

Q. Is naltrexone a controlled substance?

Naltrexone is not currently considered to be a controlled substance by the Drug Enforcement Administration (DEA) of the United States.

Q. How long does it take for low dose naltrexone to work?

Oral naltrexone is rapidly absorbed and begins working within an hour after administration. The effects of the oral pill containing 50 mg can persist between 24 and 36 hours. Higher doses have a longer duration, with 100 mg lasting for 48 hours and 150 mg for 72 hours. Typically, Naltrexone reaches its peak within one hour after administration.

Q. Does naltrexone make you sleepy?

It is possible for some people using this medication to experience side effects such as feeling lightheaded, sleepy, or less alert than they normally are.

Q. Is naltrexone addictive?

Naltrexone is used to treat opiate dependency or addiction and alcoholism.

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