Naltrexone Medications
Naltrexone is an opioid antagonist used to help reduce cravings and prevent relapse in alcohol and opioid use disorders.
Order Naltrexone Medications
About Naltrexone
Naltrexone is an opioid-receptor antagonist approved for the treatment of alcohol-dependence and the prevention of relapse to opioid dependence after detoxification. Belonging to the class of competitive antagonists at the μ-opioid receptor, it blocks the euphoric and analgesic effects of endogenous and exogenous opioids. Commercially, it is marketed under brand names such as Revia, Vivitrol and Depade, while generic tablets are widely available through our online pharmacy. Although primarily indicated for substance-use disorders, clinicians sometimes prescribe it off-label for conditions like chronic pain syndromes or certain autoimmune disorders where modulation of the opioid system may be beneficial.
What is Naltrexone?
Naltrexone is a selective, non-competitive antagonist of the μ-opioid receptor and, to a lesser extent, the κ-receptor. The Therapeutic Goods Administration (TGA) of Australia approved it in 2003 for alcohol-dependence, following prior approval by the U.S. Food and Drug Administration (FDA) in 1984 for opioid dependence. Its molecular action involves binding to opioid receptors with high affinity, preventing activation by endogenous β-endorphins or exogenous opioids such as heroin or prescription morphine. By blocking these pathways, naltrexone reduces cravings and the reinforcing effects of alcohol and opioids. The drug is supplied both as immediate-release tablets (50 mg) and as a long-acting intramuscular depot (380 mg) that releases the active compound over a month. Generic formulations are listed on the Australian Register of Therapeutic Goods (ARTG) and can be purchased through our pharmacy service.
How Naltrexone Works
Mechanism of Action
Naltrexone occupies the µ-opioid receptor’s binding pocket without activating it, thereby acting as a competitive antagonist. This blockade inhibits downstream G-protein signaling that would normally increase dopamine release in the mesolimbic reward pathway. The net effect is a dampening of the pleasurable sensations associated with alcohol ingestion or opioid use.
Therapeutic Effects
Because the reward circuitry remains inactive, patients experience reduced craving intensity and a lower likelihood of relapse. In alcohol-dependent individuals, naltrexone attenuates the reinforcing properties of ethanol, leading to fewer drinking days and decreased heavy-drinking episodes. In opioid-dependent patients who have already undergone detox, the antagonist prevents the euphoric “high” if opioids are taken, discouraging relapse.
Onset and Duration
Oral naltrexone reaches peak plasma concentrations within 1 hour, and receptor occupancy is evident within a few hours. Clinical trials show a measurable reduction in craving within 3-5 days of daily dosing. The intramuscular depot formulation achieves sustained plasma levels for up to 30 days, eliminating the need for daily tablets and improving adherence.
Approved Uses and Applications
Approved Indications
- Alcohol-dependence: For adults who have a goal of abstinence, the TGA approves 50 mg oral tablets taken once daily. Large-scale studies, such as the COMBINE trial published in The New England Journal of Medicine, reported a 20 % greater rate of abstinence compared with placebo.
- Opioid dependence (post-detoxification): After complete opioid withdrawal, a 50 mg oral daily dose reduces the risk of relapse. The extended-release Vivitrol depot (380 mg IM) is also approved for this indication, offering a once-monthly dosing schedule.
Off-Label Uses
Naltrexone is investigated off-label for chronic pain, where low-dose regimens (≈4.5 mg daily) may modulate central sensitization, and for certain autoimmune diseases such as multiple sclerosis, where modulation of the opioid-immune axis is hypothesized to exert anti-inflammatory effects. These applications are not endorsed by the TGA, and clinicians should rely on peer-reviewed evidence before prescribing.
Clinical Efficacy
In the Lancet’s 2018 meta-analysis of 33 randomized trials, naltrexone reduced total drinks per drinking day by an average of 1.6 units and increased the proportion of patients achieving three-month continuous abstinence by 15 % relative to placebo. For opioid dependence, a double-blind trial published in JAMA Psychiatry demonstrated a 30 % lower relapse rate over 12 weeks with the monthly depot compared to standard counseling alone.
Buying Naltrexone from Our Online Pharmacy
Why Choose Our Service
Access to naltrexone can be limited by geographic distance from major pharmacies or by insurance formularies that favor brand-only options. Through our platform, Australian adults can obtain both branded and generic versions with transparent pricing, secure checkout and discreet packaging.
Brand Names and Generic Options
- Revia - 50 mg oral tablet, brand-price comparable to generic.
- Vivitrol - 380 mg intramuscular depot, monthly injection.
- Depade - 50 mg tablet marketed for alcohol-dependence.
- Generic naltrexone - identical active ingredient, typically 20-30 % cheaper than branded equivalents.
Quality & Safety
We partner with licensed international pharmacies that comply with WHO Good Manufacturing Practices and are audited by the Australian Pharmacy Guild. All shipments are handled under the TGA’s imported-medicine framework to ensure authenticity.
Pricing & Access
Generic tablets start at AU$.75 per 50 mg dose, while the depot formulation is available for AU$120 per injection. A Lifetime 10 % discount applies to all repeat orders placed through our online pharmacy.
Discreet Delivery
Express shipping arrives within 7 days, standard within 3 weeks. Packages are sealed in unmarked, tamper-evident containers to protect privacy.
Dosing, Formulations & Administration
Available Formulations
- Immediate-release tablets: 50 mg, taken orally.
- Extended-release intramuscular injection: 380 mg, administered by a healthcare professional once every 4 weeks.
Typical Dosing Ranges
- Alcohol-dependence: 50 mg tablet once daily, often initiated after a medical assessment confirming liver function is within acceptable limits.
- Opioid dependence (post-detox): 50 mg tablet daily for 7-10 days, followed by the 380 mg depot for ongoing relapse prevention.
Administration Guidelines
Oral tablets may be taken with or without food; however, taking them with a light meal can reduce occasional nausea. The intramuscular depot must be injected into the gluteal muscle by a qualified practitioner. Patients should avoid concurrent use of opioid analgesics, as the antagonist will negate pain relief and may precipitate withdrawal.
Exact dosing must be individualized by a healthcare professional based on medical history, hepatic function, and concurrent therapies.
Safety Profile & Considerations
Common Side Effects
- Nausea (≈12 % of users)
- Headache (≈10 %)
- Dizziness (≈8 %)
- Fatigue (≈7 %)
- Insomnia (≈5 %)
These events are generally mild and resolve within the first two weeks of therapy.
Serious Adverse Events
- Hepatotoxicity: Elevations in transaminases >3 × ULN have been reported; monitoring liver enzymes before initiation and periodically thereafter is advised.
- Severe depression or suicidal ideation: Rare (≈.2 %); patients with a history of mood disorders should be observed closely.
- Hypersensitivity reactions: Rash, pruritus, or anaphylaxis require immediate medical attention.
Contraindications
- Acute opioid intoxication or dependence (risk of precipitated withdrawal)
- Severe hepatic impairment (Child-Pugh C)
- Known hypersensitivity to naltrexone or any excipients
Drug Interactions
- CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) may increase naltrexone plasma concentrations, warranting dose adjustment.
- Other opioid antagonists (naloxone) have additive blocking effects and should be avoided concurrently.
- Opioid analgesics will be ineffective while naltrexone is active; alternative pain strategies must be employed.
Special Populations
- Pregnancy & breastfeeding: Limited data; the TGA advises use only if the potential benefit outweighs risk.
- Elderly: Start at the lower end of the dosing range; monitor for hepatic function and falls due to dizziness.
- Renal or hepatic impairment (mild-moderate): No dose reduction is required, but labs should be checked regularly.
Frequently Asked Questions
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How does naltrexone differ from naloxone? Naltrexone is a longer-acting oral or depot antagonist used for maintenance therapy, whereas naloxone is an injectable, rapid-acting antagonist employed to reverse acute opioid overdose.
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How long does naltrexone take to work for alcohol dependence? Patients often notice a reduction in craving within 3-5 days of consistent daily dosing, with maximal benefit observed after 4-6 weeks of therapy.
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Can I drink alcohol while taking naltrexone? Naltrexone reduces the rewarding effects of alcohol but does not prevent intoxication. Continued drinking may blunt therapeutic gains and increase liver strain.
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What should I do if I experience nausea from naltrexone? Take the tablet with food, stay hydrated, and discuss persistent nausea with your clinician, who may adjust the dose or suggest anti-emetic support.
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Is the monthly Vivitrol injection safe for people with liver disease? The depot formulation carries the same hepatic warnings as oral tablets; baseline liver function tests are required, and ongoing monitoring is essential.
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Does taking naltrexone with food affect its absorption? Food does not significantly alter bioavailability, but a light meal can mitigate gastrointestinal upset.
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Can naltrexone be used for chronic pain? Low-dose naltrexone (≈4.5 mg) is studied off-label for certain pain conditions, but robust evidence is lacking. Discuss experimental use with a pain specialist.
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What foods should I avoid while on naltrexone? No specific dietary restrictions exist, but excessive alcohol consumption should be avoided to protect liver health.
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How often will I need follow-up appointments? Initial review after 2 weeks to assess tolerance, then monthly or quarterly visits to monitor liver enzymes and treatment response.
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What information should I provide my doctor when discussing naltrexone?
- Complete list of current medications, including over-the-counter drugs and supplements
- History of liver disease, hepatitis, or elevated liver enzymes
- Details of any prior opioid use or dependence
- Treatment goals (abstinence vs. reduction) and any previous attempts at therapy
Disclaimer
The information provided about naltrexone is for general knowledge only. It does not replace professional medical consultation or the official prescribing information for medications containing this ingredient. All treatment decisions, including dosing, formulation selection, and monitoring, should be made under the supervision of a qualified healthcare provider who can assess individual medical history, current medications, and specific health needs. We assume all readers are responsible adults capable of making informed decisions about their health. Our online pharmacy offers access to medications containing naltrexone for individuals who may have limited availability through traditional pharmacies, prescription-based insurance schemes, or who are seeking affordable generic alternatives. Always consult your doctor before starting, changing, or discontinuing any medication containing naltrexone.
