Naloxone vs Naltrexone - Comparison of Uses & Side Effects

Naloxone

This drug belongs to a group of drugs called opioid antagonists. It can be found under the brand name of Evzio.

This medication works by blocking the effects of opioids to relieve life-threatening symptoms caused by high levels of opioids in the blood.

Mechanism of Action

It works by binding to mu-receptors in the brain which opioids use to produce their effect on pain and other symptoms. By binding to this receptors, this opioid antagonist reverses opioid activity in the body.

Examples of opioid painkillers that people may get addicted to include OxyContin (oxycodone), Norco (hydrocodone/acetaminophen), and codeine.

Uses

This prescription medication is used to treat an opioid overdose, side effects of opioids,  and opioid effects in babies delivered by mothers with opioid addiction.

Neonatal abstinence syndrome (NAS) occurs when a baby is exposed to drugs (and develops a dependence) in the womb before birth. But because the baby is no longer receiving the drugs through the placenta, withdrawal symptoms may occur.

Over 24,000 babies that were born in 2013 (the last year for which statistics are available) experienced symptoms of opioid withdrawal in the United States. This is a five-fold increase since 2000.

Symptoms of neonatal abstinence syndrome may vary depending on the type of substance used, whether the baby is full-term or premature, and the last time it was used. Symptoms of withdrawal may begin as early as 24 hours after birth and may include:

  • high-pitched crying;
  • tremors (trembling);
  • hyperactive reflexes;
  • irritability (excessive crying);
  • stuffy nose and sneezing;
  • yawning;
  • seizures;
  • insomnia (sleep problems);
  • vomiting;
  • tight muscle tone;
  • sweating;
  • poor feeding and a weak suck;
  • fever or unstable temperature;
  • dehydration;
  • diarrhea.

Note – this medication will work even with more potent opioids, like – fentanyl, but higher doses may be required.

Dosage

In children, the usual recommended dose for IV use is 0.01 mg/kg body weight. If the desired effect is not obtained, a subsequent dose of 0.1 mg/kg body weight may be administered.

In adults, the usual recommended dose for IV, IM, and SQ is 0.4 mg to 2 mg. If the desired effect is not obtained, the treatment may be repeated at 2 to 3-minute intervals.

Note – when given into a vein, this medication takes a few minutes to start working and its effects last for about 60 minutes.

Side Effects and Precautions

Common side effects may include:

  • trembling;
  • shortness of breath;
  • paraesthesia (tingling or pricking);
  • nausea;
  • vomiting;
  • hypoxia (oxygen deficiency);
  • sweating;
  • fast heart rate;
  • flushing;
  • hot flushes;
  • injection site reactions;
  • respiratory depression (breathing problems);
  • cardiac arrest (sudden loss of heart function).

Rare side effects may include:

  • cardiac arrhythmias;
  • agitation;
  • seizures;
  • high or low blood pressure;
  • coma;
  • abnormal brain function (encephalopathy);
  • pulmonary edema.

Pregnancy & Breastfeeding

It is not known precisely whether this medication enters breast milk; hence, it is recommended to be cautious before using if you are breast-feeding a baby.

Also, there are no well-done clinical studies to determine the safety of this medication in pregnant women.

Addiction

No habit forming tendency has been reported.

Alcoholalcohol

Try to avoid or limit drinking alcoholic beverages while taking this medication since alcohol could increase the risk of side effects.

Drug Interactions

It may negatively interact with other medications, especially:

  • Rybix, Conzip, Ultram, Ryzol, or Ultracet (tramadol);
  • farxiga;
  • drugs that contain topiramate, such as – Qsymia or Topamax;
  • the supplement yohimbine;
  • intuitiv;
  • any drugs in the opioid family, including Zohydro (hydrocodone); codeine; Dilaudid (hydromorphone); Subsys (fentanyl); and Opana ER (oxymorphone).

Naltrexone 

It is a drug that belongs to a group of drugs called opiate antagonists. It can be found under the brand name of ReVia.

Mechanism of Action

This medication works by blocking the effects of opiate medications and opioid street drugs and reducing the craving for alcohol.

It was originally approved in 1994 by the US FDA to help alcohol abusers safely detox from alcohol. In October 2010, the US Food and Drug Administration approved it for people in recovery from opioid addiction.

Uses

This prescription medication is used to treat opioid drug abuse and alcohol dependence.

Additionally, low doses of naltrexone (LDN) may reduce the severity of symptoms in fibromyalgia, multiple sclerosis, complex regional pain syndrome (a chronic pain condition which most often affects one limb), Crohn’s disease, and other chronic pain disorders.

Dosage

For opioid dependence, the treatment should be initiated with an initial dose of 25 mg. If no withdrawal signs occur, the sufferer may be started on 50 mg a day thereafter.

For alcoholism, the usual recommended dose is 50 mg once per day for up to 12 weeks.

Note – to reduce the risk of precipitated withdrawal, sufferers should abstain from opioid medication and illegal opioids for a minimum of 7-10 days before starting the treatment.

The use of this medication in patients with the active liver disease must be carefully considered in light of its hepatotoxic effects. Also, it is contraindicated in people with liver failure or acute hepatitis.

Side Effects and Precautions

Common side effects may include:

  • feeling anxious or nervous;
  • stomach pain;
  • sleep problems (insomnia);
  • vomiting;
  • muscle or joint aches;
  • drowsiness;
  • dizziness;
  • headaches;
  • nausea.

Rare side effects may include:

  • thoughts about suicide or hurting yourself;
  • severe vomiting, nausea, or diarrhea;
  • depression;
  • hallucinations (seeing or hearing things);
  • jaundice (yellowing of the skin or eyes);
  • confusion;
  • clay-colored stools;
  • dark urine;
  • loss of appetite;
  • tired feeling;
  • upper stomach pain;
  • mood changes.

Drug Interactions

It may negatively interact with other medications, especially:

  • Thioridazine;
  • Disulfiram (Antabuse);
  • certain medications for cough, diarrhea, or pain;
  • street drugs or opioid (narcotic) medications, such as – levomethadyl acetate or methadone (Methadose, Dolophine).

Pregnancy & Breastfeeding

It is unknown whether this medication could harm a breastfeeding infant. Therefore, talk to your healthcare provider before breastfeeding while taking this opiate antagonist.

More importantly, it might harm an unborn baby. Hence, talk to your healthcare professional about using this opiate antagonist if you are pregnant or plan to fall pregnant.

Alcohol

You shouldn’t consume alcoholic beverages while taking this opiate antagonist since alcohol can considerably increase the risk of unnecessary side effects.

Bottom Line – Naloxone vs Naltrexone 

Naloxone (brand name – Evzio) is used to treat a narcotic overdose in an emergency situation. This opiate antagonist should not be used in place of emergency medical care for an overdose.

Naltrexone (brand name – ReVia) is used to treat alcoholism by reducing your urge to drink alcohol. Also, this opiate antagonist is used to prevent relapse in people who became dependent on opioid medicine.

According to studies, Naltrexone is a more potent opioid antagonist than Naloxone and with a greater oral bioavailability and a longer biologic half-life.

References

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2661437/
https://www.theatlantic.com/health/archive/2018/03/moral-hazard-opioid/555389/
https://www.ncbi.nlm.nih.gov/pubmed/12878920