Resistent Post Herpetic Neuralgia Treatments – IV Magnesium for Neuropathic Pains

Three IV Magnesium  1mg /k in 100 mls saline  infusions over 1 hour – one every other day or Three 1 mg/kg Ketamine in 100 mls saline infused in over 1 hour ketamine  one EOD resulted in 7/15 magnesium and 10/15 ketamine patients having >/= 50% improvement in pain .  Both had Midazolam 0.1 mg/kg to render them unconscious though in actuality only some would be needed for ketamine to treat the dysphoria achieved at higher doses..

J Clin Anesth. 2015 Mar 17. pii: S0952-8180(15)00053-7. doi: 10.1016/j.jclinane.2015.02.006. [Epub ahead of print]
Is magnesium sulfate effective for pain in chronic postherpetic neuralgia patients comparing with ketamine infusion therapy?
Kim YH(1), Lee PB, Oh TK

  • Intractable Post herpetic neuralgia with VAS >7/10 for  >/=6 months+
  • Heart block, digoxin use, or renal impairment excluded. An ECG was done prior
  • Both Ketamine and Magnesium work on NMDA receptors, a unique target from other forms of neuropathic pain treatments except Methadone And Dextromethorphan.
  • DN4 symptoms:


  • “midazolam intravenously (0.1 mg/kg) to render them unconscious” as part of blinding technique (put them asleep) but at a lower does would have been a necessary addition to ketamine to block dysphoric reactions
  • Ketamine 1 mg/ kg or magnesium 30 mg /kg  was dissolved in 100 mls saline and run in over 1 hour.
  • This was repeated every other day x3


  • Results-  persistent 2weeks after last infusion:
  • On average, ketamine persistently reduced pain 51% and magnesium 39.6%. Worthwhile results (>30%) were seen in 12/15 ketamine and 11/15 magnesium.

Side Effects

  • Side effects – somnolence and dizziness (consider using oxymeter). “One patient in the magnesium group complained of mild chest tightness”. The every other day program allowed people to get over the drug feelings. One in ketamine group had nausea.

Other studies using Magnesium:

  • Brill S, Sedgwick PM, Hamann W, Di Vadi PP. Efficacy of intravenous
    magnesium in neuropathic pain. Br J Anaesth 2002;89:711-4.
    -single infusion
  • Begon S, Pickering G, Eschalier A, Dubray C. Magnesium increases morphine analgesic effect in different experimental models of pain. Anesthesiology 2002;96:627-32.
    – augmented effects of morphine
  • Mauskop A, Altura BT, Cracco RQ, Altura BM. Intravenous magnesium sulfate relieves migraine attacks in patients with low serum ionized magnesium levels: a pilot study. Clin Sci 1995;89: 633-6.
    – IV magnesium 1 gm
    – 21/40 got persistent >50% headache relief
  • Tanaka M, Shimizu S, Nishimura W, Mine O, Akatsuka M, Inamori K,
    et al. Relief of neuropathic pain with intravenous magnesium. Masui
    – used o.5 mmol/l = 1.3 gm/liter
    – small doses had significant effect
  • Cheong YK, Kim TY, Lee JH. The trial of continuous intravenous
    infusion of magnesium in patients with postherpetic neuralgia
    refractory in conventional treatment. Korean J Anesthesiol 2006;50:
    -put 1200 mg in 50 cc in infusion pump “injected into 1 hours”
    – mentioned 3 times – maybe like first article
    -got considerable relief of pain
  • Collins, Susan, et al. “Intravenous magnesium for complex regional pain syndrome type 1 (CRPS 1) patients: a pilot study.” Pain medicine 10.5 (2009): 930-940.“Eight patients received 70 mg/kg magnesium sulphate infusions in 4 hours for 5 days”
    I wrote that up here:
    New Hope For Complex Regional Pain Syndrome I – 5 days Magnesium Infusions
  • J Pain Symptom Manage. 2000 Jan;19(1):35-9. The safety and efficacy of a single dose (500 mg or 1 g) of intravenous magnesium sulfate in neuropathic pain poorly responsive to strong opioid analgesics in patients with cancer. Crosby V, Wilcock A, Corcoran R– 12 patients with neuropathic pain due to malignant infiltration of the brachial or lumbosacral plexus- both 500 mg and 1000 mg effective in 4/12 temporarily complete, 6/12 partial. Unfortunately pain was back in 4 hours. Besides a feeling of warmth – no side effects- “One ml or 2 ml of 50% w/v magnesium sulfate… given intravenously over 5 or 10 minutes (500 mg or 1 g, respectively).”    Not sure I could get away with giving Magnesium IV that concentrated without getting arm burning pain – but these subjects were on a lot of painkillers.


  • I wrote up this topic in 2008:
    IV Magnesium Studies
    At time, I was not convinced a single infusion had much effect – and it looks like that at least 3 -5 infusions on alternate days would be necessary.

Adding in Ketamine or ketamine/Lidocaine

  •  I suspect if ketamine was given on the alternate days then the results could be multiplied – Either given by the anodynehealth approach:
    “0.3-0.4 mg per kilogram of ketamine was drawn into a syringe. The dose was injected in three to four portions intramuscularly, with 10 to 15 minutes between
    injections. The patient rated their pain and headache score on a 0 to 10 VAS or numeric rating score (NRS).
    10 patients were suffering primarily from refractory migraines seven patients primarily from exacerbation of pain (lumbar and cervical radiculopathy, TN, orofacial pain, CRPS). One patient was suffering from ongoing cluster headaches. Some patients (n=5) received more than 1 set of IM ketamine injections. “
  • or once with Dr. Ellen Thompson’s ketamine-lidocaine infusion

Comment – It looks hopeful that repeated magnesium or ketamine infusions could give persistent relief when all else fails. Diluting the magnesium helps it burn less otherwise you will be putting ice on sore veins (I have had to do that). Magnesium can be hard on veins and so if patient has some varicose veins in legs, you might be able to rid him/her of some by giving infusion there… I am a big believer in critical mass – sufficient measures to reach substantive improvement and most chronic pain sufferers will need that:
Reaching “Critical Mass” to Achieving Pain Control – Procedure Pearls


This entry was posted in central & spinal, complex regional pain, Drugs, IV therapy, neuropathic, Pain Dystrophy, post herpetic neuralgia, radiculitis. Bookmark the permalink.

One Response to Resistent Post Herpetic Neuralgia Treatments – IV Magnesium for Neuropathic Pains

  1. Gabapentin has been shown to bind to the ?2?-1 subunit of voltage gated calcium ion channels , which contributes to its pain attenuation effects in diabetic neuropathy and post-herpetic neuralgia. Other neurophysiological findings indicate that gabapentin also interacts with NMDA receptors , protein kinase C , and inflammatory cytokines .

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