A Case Series and Review of Literature on Low-Dose Naltrexone: An Alternative Therapy for Post-Herpetic Neuralgia
Alejandro Hallo-Carrasco, MD1; Daniel Cho, BS 1; Kevin Tang, BS 1; Mia Castiglione, DO 1; Haijun Zhang, MD 1; Andrew Kaufman, MD 1
1Rutgers New Jersey Medical School – Anesthesiology Department
Introduction
•The intensive medication regimen for managing Post-Herpetic Neuralgia (PHN) can lead to uncomfortable side effects, compromising patients' wellbeing and increasing drug tolerance.
•These challenges have driven the exploration of novel therapies like low-dose naltrexone (LDN), which has been successfully used at our comprehensive pain clinic.
Methods
•Three cases managed with LDN in our pain medicine clinic were reviewed after obtaining informed consent by primary investigator.
•As the cases reported devoid of patient identifiable information, it is exempt from IRB review requirements as per University Hospital policy.
Case 1
•A 69-year-old female PMHx of liver cirrhosis, hypertension, osteoarthritis, and sarcoidosis presented with burning and shooting pain in the T9-T11 dermatome.
•Previous unsuccessful regiments: Initial therapy included physical therapy, tramadol, oral baclofen, topical and oral cannabinoids, and pregabalin. Significant sedation with tramadol.
•Naltrexone regimen: 3.5 mg daily titrate up over two years, combined with pregabalin 200 mg TID.
•She reported over 70% pain relief with 2.5 mg LDN with no adverse effects, allowing for significant daily activity improvement.
Case 2
•A 67-year-old female PMHx of transient ischemic attack and ulcerative colitis presented with PHN in the right T1 distribution.
•Previous unsuccessful regiments: pregabalin, gabapentin, oxcarbazepine, duloxetine, capsaicin patches, acupuncture, medical marijuana, and topical emollients.
•Naltrexone regimen: 1 mg of LDN at bedtime along with a 5:1 ratio cannabinoid in the morning.
•One month after starting LDN, she reported significant nighttime pain improvement, though she still experienced daytime hyperalgesia. Increasing her dose to 1 mg TID resulted in significant overall pain reduction and improved quality of life.
Case 3
•An 81-year-old female with a PMHx of type II diabetes mellitus, hypertension, hyperlipidemia, and hypothyroidism presented with PHN in the C2 dermatome.
•Previous unsuccessful regiments: gabapentin, pregabalin, tramadol, and ibuprofen. Drowsiness and cognitive dysfunction.
•Naltrexone regimen: 2.5 mg BID of LDN.
•Within two weeks of restarting LDN, her pain was significantly reduced without notable side effects, and adjuvant medication was titrated down to a minimum.
Conclusion
Low-dose naltrexone (LDN) shows potential as an alternative treatment for post-herpetic neuralgia (PHN), offering anti-inflammatory effects and alleviating chronic pain without causing resistance or dependence, unlike traditional therapies.
Recommended dose:
Low dose of 0.1 to 4.5 mg exert anti-inflammatory effects and may alleviate central chronic pain.
References
1. Resnick, R. B. Studies of EN-1639A (naltrexone): a new narcotic antagonist. American Journal of Psychiatry, 131(6), 646-650.
2. Srivastava, A. B. Naltrexone: a history and future directions. In Cerebrum: the Dana forum on brain science (Vol. 2018). Dana Foundation. 2018
3. Poliwoda, S. Utilization of Low Dose Naltrexone for Chronic Pain. CNS drugs 2023
