Low Dose Naltrexone (LDN) and Long Covid
including a pediatric perspective
As I have read and heard a lot about the possible role of Low Dose Naltrexone (LDN) in patients with Long Covid and – I confess – I have very little experience and knowledge on this topic, I decided to study a bit … for me, and for you as well.
Naltrexone was synthesized in 1963 as an orally active competitive opioid receptor antagonist. Naltrexone is structurally and functionally similar to the opioid antagonist naloxone, but it has greater oral bioavailability and a longer biologic half-life.
The typical daily dosage for opioid addiction is 50.0–100.0 mg daily, and 50.0-mg tablets are available commercially LDN refers to daily dosages of naltrexone that are approximately 1/10th of the typical opioid addiction treatment dosage. In most published research, the daily dosage is 4.5 mg, though the dosage can vary a few milligrams below or above that common value.
At the low dosage level, naltrexone exhibits paradoxical properties, including analgesia and anti-inflammatory actions, which have not been reported at larger dosages.
Authors have shown in two separate, small clinical trials that LDN may be an effective treatment for fibromyalgia. In both trials, LDN was administered at 4.5 mg daily, once at night before bedtime. In the first crossover trial, published in 2009, LDN reduced fibromyalgia pain significantly greater than placebo in 6 out of the 10 women. While the pilot study was encouraging, it had limitations such as a single-blind design. In a double-blind, crossover, counterbalanced study, 57 % of the participants were observed to exhibit a significant (1/3) reduction of pain during LDN. At the end of the LDN treatment, half of the participants reported feeling “much improved” or “very much improved” from LDN. Together, these two studies suggest that LDN is superior to placebo in reducing the pain associated with fibromyalgia.
These early studies opened a significant amount of interest for this compound. Below there is a summary of the most interesting biological activities of LDN that may be of particular interest for Long Covid and ME/CFS (myalgic encephalomyelitis / chronic fatigue syndrome), including in children.