Naltrexon "walter Ritter" (Naltrexone Hydrochloride)

Naltrexone is used within the opioid and alcohol dependence therapeutic pathways to reduce relapse risk and diminish rewarding effects of substances.

• Alcohol dependence: helps maintain abstinence by blocking reinforcing effects of alcohol.
• Opioid dependence: supports relapse prevention after detoxification by antagonising mu‑opioid receptors.
• Opioid dependence (maintenance phase): used as an adjunct to psychosocial therapy to reduce cravings.

• Naltrexone acts as a competitive antagonist at opioid receptors, primarily the mu‑opioid subtype. By binding to these receptors without activating them, it blocks the effects of both endogenous opioids and exogenous opioid agonists, thereby diminishing the rewarding and reinforcing properties of alcohol and opioid substances.

Naltrexone may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Headache: transient cranial discomfort.
• Dizziness: occasional light‑headedness.
• Fatigue: reduced energy levels.
• Insomnia: difficulty initiating or maintaining sleep.
• Abdominal pain: mild stomach discomfort.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or liver injury.
• Severe depression: mood changes requiring medical attention.
• Suicidal ideation: thoughts of self‑harm.
• Allergic reactions: rash, pruritus, or angioedema.
• Seizures: rare convulsive events.

When prescribing Naltrexone, clinicians should consider several safety measures.

• Liver function assessment: evaluate baseline hepatic enzymes before initiation.
• Depression monitoring: watch for worsening mood or suicidal thoughts.
• Acute opioid withdrawal: avoid use during active withdrawal to prevent precipitated symptoms.
• Concomitant opioid analgesics: do not combine, as analgesic effect will be blocked.
• Pregnancy and lactation: safety data are limited; use only if clearly needed.
• Store below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Naltrexone can interact with other medicines, requiring careful management.

Major Interactions (Avoid)

• Opioid analgesics (e.g., morphine, oxycodone): antagonises analgesic effect and may precipitate withdrawal.
• Opioid agonist therapy (methadone, buprenorphine): reduces therapeutic benefit and can cause abrupt discontinuation symptoms.
• Alcohol: may increase risk of hepatotoxicity.

Moderate Interactions (Monitor Closely)

• CNS depressants (benzodiazepines, barbiturates): additive sedation.
• Antidepressants (SSRIs, SNRIs): monitor for mood changes.
• Antihypertensives: possible additive hypotensive effect.