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7 Important facts about Naltrexone

by egpat         30 May 2024

Naltrexone is one of the medications that can be used for the treatment of chronic alcoholism. It can also be used for the treatment of opioid addiction, so in both of these cases, naltrexone can reverse addiction to alcohol or opioids. But before taking naltrexone, you should know important things such as the effect of this drug on the liver, who can take this medication, how to reverse the effect of naltrexone under emergency conditions, what are the toxic effects of this medication, and what to avoid while using it.

All these things are very important and highly essential. So while using Naltrexone, you should know all these things for better management and safe treatment. So today in this post, let's discuss seven important things about naltrexone.

Naltrexone is available in two dosage forms: the tablet and the intramuscular injection. Obviously, intramuscular injections should be carefully given because the drug is directly administered into the blood circulation, and any excess of this dose may lead to a few of the toxic effects. So, compared with oral tablets, intramuscular injections should be carefully given. But even with the use of oral tablets, we have to know a few important things, so let us start our discussion one by one.

1. Effect on liver

Naltrexone is metabolized within the liver, and one of its active metabolites is 6-betanaltrexol. At regular doses such as 50 mg of naltrexone, both of these components are not producing any significant effect on the liver. However, at higher doses, such as 300 mg, both naltrexone and its metabolite can produce some hepatotoxicity, resulting in hepatocellular injury. Any symptoms like abdominal pain, diarrhea, nausea and vomiting, yellowing of the skin as well as the eyes, an unexpected loss of appetite, and some joint pains may indicate the development of acute hepatitis in people.

So while using naltrexone for longer periods, if these symptoms develop, then liver functionality should be carefully monitored. This is the first important precaution while using naltrexone. That's why it is always better to use naltrexone at lower doses in order to avoid any damage to the liver.

2. Opioid-free period

Naltrexone is given to people who are free from opioids because it has an inhibitory effect on opioids. Opioids like morphine and buprenorphine can be used as analgesics, and for those who are using opioids, naltrexone should not be given because it can precipitate withdrawal symptoms.

Since naltrexone acts as an antagonist, in its presence, opioids produce the opposite effect, resulting in withdrawal symptoms. That's why at least a 7- to 10-day gap should be maintained between the withdrawal of opioids and the introduction of naltrexone. Therefore, before using naltrexone, a naloxone challenge test is done in order to assess the presence of opioids in the body and avoid the risk of withdrawal symptoms.

Similarly, urine tests can also be done in order to check for the presence of opioids. When it is confirmed that the patient is free of opioids, naltrexone can be administered. Without this precaution, the use of naltrexone may lead to the development of withdrawal symptoms.

3. Common side effects

Naltrexone can have some inhibitory effects on the CNS. So it can produce some dizziness, sleepiness, sedation, and headaches in people. These are the common side effects of naltrexone, which are well tolerated. Any severe dizziness or sedation may indicate any interaction of naltrexone with other centrally depressant drugs.

4. Opioid tolerance

Naltrexone inhibits opipid activity. However, at the end of the dosing interval, due to the loss of naltrexone activity, opioid activity may be enhanced and tolerance can be reduced. Therefore, even a low dose of opioids can produce an effect that is equal to that of a high dose of opioids. So even with a small dose of opioid, a large effect can be observed because of reduced opioid tolerance, which is clearly observed in the absence of naltrexone activity.

This effect can also be observed in cases of missed doses of naltrexone. In such conditions, in the absence of naltrexone, we can observe an enhanced effect of opioids. This may lead to opioid intoxication, which can produce a variety of systemic complications. A few symptoms, like confusion, decreased alertness and awareness, difficulty breathing because of respiratory depression, nausea and vomiting, and excessive sleepiness, can be observed with reduced opioid tolerance. That's why, at the end of naltrexone treatment, opioids should not be used at regular doses but should be used at lower doses in order to avoid opioid intoxication.

5. Use of analgesics

In a few emergency conditions, it is required that naltrexone treatment be reversed in order to produce the analgesic activity of opioids. For pain management, opioids are required, and opioids will not act in the presence of naltrexone. So under emergency conditions where pain management is essential, naltrexone activity should be reversed. In such conditions, opioids cannot be administered directly for pain management. In the presence of naltrexone, opioids are ineffective.

So in order to reverse the action of naltrexone and for pain management, regional analgesia is preferred by the administration of local anesthetics, and the use of non-opioid analgesics is preferred. However, for those who are unable to control the pain in these two ways, opioids should be administered under very close monitoring by a professional to produce pain management without any adverse effects from naltrexone.

6. Opioid withdrawal symptoms

At higher doses, naltrexone can precipitate opioid withdrawal symptoms. This may lead to the development of nervousness, agitation, palpitations, and an increased heartbeat, along with some awareness of the heartbeat. Even tremors can be observed in people. These are a few of the opioid withdrawal symptoms that can be observed with higher doses of naltrexone.

7. Switching from opioid agonists

For the management of opioid dependence, a few of the drugs that have weak opioid activity can be used. Generally, few drugs like methadone and buprenorphine are preferred, which are weak opioid agonists and somewhat long-acting. They can produce opioid activity without producing significant euphoria or respiratory depression.

On the other hand, naltrexone can be used for the management of opioid addiction because it inhibits the activity of opioids. So here, both of these clinical indications are completely different. That's why naltrexone should not be combined with opioid agonists like methadone and buprenorphine because they can precipitate withdrawal symptoms when combined.

This is very essential before using naltrexone. The patient should be free of opioids for at least 7 to 10 days, and the patient should have a successful naloxone challenge test and urine test. Even the administration of weak opioid agonists like methadone and buprenorphine is not preferred in the presence of naltrexone. So these are the seven important things that we should know before using naltrexone.

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