Glia a Promising Target for Neuropathic Pain – Ketamine Acting on Glia More Than on Neuronal NMDA Receptors?

01/30/2012 — Nancy Sajben MD
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 Three important new articles from March, August and November 2011, show ketamine acts on glia.

Emphasis within articles is mine.

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Microglia: a promising target for treating neuropathic and postoperative pain, and morphine tolerance.

Abstract

Management of chronic pain, such as nerve-injury-induced neuropathic pain associated with diabetic neuropathy, viral infection, and cancer, is a real clinical challenge. Major surgeries, such as breast and thoracic surgery, leg amputation, and coronary artery bypass surgery, also lead to chronic pain in 10-50% of individuals after acute postoperative pain, partly due to surgery-induced nerve injury. Current treatments mainly focus on blocking neurotransmission in the pain pathway and have only resulted in limited success. Ironically, chronic opioid exposure might lead to paradoxical pain. Development of effective therapeutic strategies requires a better understanding of cellular mechanisms underlying the pathogenesis of neuropathic pain. Progress in pain research points to an important role of microglial cells in the development of chronic pain. Spinal cord microglia are strongly activated after nerve injury, surgical incision, and chronic opioid exposure. Increasing evidence suggests that, under all these conditions, the activated microglia not only exhibit increased expression of microglial markers CD 11 b and Iba 1, but also display elevated phosphorylation of p38 mitogen-activated protein kinase. Inhibition of spinal cord p38 has been shown to attenuate neuropathic and postoperative pain, as well as morphine-induced antinociceptive tolerance. Activation of p38 in spinal microglia results in increased synthesis and release of the neurotrophin brain-derived neurotrophic factor and the proinflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α. These microglia-released mediators can powerfully modulate spinal cord synaptic transmission, leading to increased excitability of dorsal horn neurons, that is, central sensitization, partly via suppressing inhibitory synaptic transmission. Here, we review studies that support the pronociceptive role of microglia in conditions of neuropathic and postoperative pain and opioid tolerance. We conclude that targeting microglial signaling might lead to more effective treatments for devastating chronic pain after diabetic neuropathy, viral infection, cancer, and major surgeries, partly via improving the analgesic efficacy of opioids.

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Ketamine depresses toll-like receptor 3 signaling in spinal microglia in a rat model of neuropathic pain.

Abstract

Reports suggest that microglia play a key role in spinal nerve ligation (SNL)-induced neuropathic pain, and toll-like receptor 3 (TLR3) has a substantial role in the activation of spinal microglia and the development of tactile allodynia after nerve injury. In addition, ketamine application could suppress microglial activation in vitro, and ketamine could inhibit proinflammatory gene expression possibly by suppressing TLR-mediated signal transduction. Therefore, the present study was designed to disclose whether intrathecal ketamine could suppress SNL-induced spinal microglial activation and exert some antiallodynic effects on neuropathic pain by suppressing TLR3 activation. Behavioral results showed that intrathecal ketamine attenuated SNL-induced mechanical allodynia, as well as spinal microglial activation, in a dose-dependent manner. Furthermore, Western blot analysis displayed that ketamine application downregulated SNL-induced phosphorylated-p38 (p-p38) expression, which was specifically expressed in spinal microglia but not in astrocytes or neurons. Besides, ketamine could reverse TLR3 agonist (polyinosine-polycytidylic acid)-induced mechanical allodynia and spinal microglia activation. It was concluded that intrathecal ketamine depresses TLR3-induced spinal microglial p-p38 mitogen-activated protein kinase pathway activation after SNL, probably contributing to the antiallodynic effect of ketamine on SNL-induced neuropathic pain.

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Microglial Ca(2+)-activated K(+) channels are possible molecular targets for the analgesic effects of S-ketamine on neuropathic pain.

Abstract

Ketamine is an important analgesia clinically used for both acute and chronic pain. The acute analgesic effects of ketamine are generally believed to be mediated by the inhibition of NMDA receptors in nociceptive neurons. However, the inhibition of neuronal NMDA receptors cannot fully account for its potent analgesic effects on chronic pain because there is a significant discrepancy between their potencies. The possible effect of ketamine on spinal microglia was first examined because hyperactivation of spinal microglia after nerve injury contributes to neuropathic pain. Optically pure S-ketamine preferentially suppressed the nerve injury-induced development of tactile allodynia and hyperactivation of spinal microglia. S-Ketamine also preferentially inhibited hyperactivation of cultured microglia after treatment with lipopolysaccharide, ATP, or lysophosphatidic acid. We next focused our attention on the Ca(2+)-activated K(+) (K(Ca)) currents in microglia, which are known to induce their hyperactivation and migration. S-Ketamine suppressed both nerve injury-induced large-conductance K(Ca) (BK) currents and 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS1619)-induced BK currents in spinal microglia. Furthermore, the intrathecal administration of charybdotoxin, a K(Ca) channel blocker, significantly inhibited the nerve injury-induced tactile allodynia, the expression of P2X(4) receptors, and the synthesis of brain-derived neurotrophic factor in spinal microglia. In contrast, NS1619-induced tactile allodynia was completely inhibited by S-ketamine. These observations strongly suggest that S-ketamine preferentially suppresses the nerve injury-induced hyperactivation and migration of spinal microglia through the blockade of BK channels. Therefore, the preferential inhibition of microglial BK channels in addition to neuronal NMDA receptors may account for the preferential and potent analgesic effects of S-ketamine on neuropathic pain.

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The material on this site is for informational purposes only,

The material on this site is for informational purposes only,

and is not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider.


For My Home Page, click here: 

Welcome to my Weblog on Pain Management!

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Posted in Chronic Pain, Glia, Ketamine, Neuropathy, Neuroprotective. Tags: , , , . Leave a Comment »

Gliopathic Pain — when Neuropathic Pain Treatment Fails

01/29/2012 — Nancy Sajben MD

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Coming soon, though these stand on their own:

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Modulation of microglia can attenuate neuropathic pain symptoms and enhance morphine effectiveness.

Abstract

Microglia play a crucial role in the maintenance of neuronal homeostasis in the central nervous system, and microglia production of immune factors is believed to play an important role in nociceptive transmission. There is increasing evidence that uncontrolled activation of microglial cells under neuropathic pain conditions induces the release of proinflammatory cytokines (interleukin – IL-1beta, IL-6, tumor necrosis factor – TNF-alpha), complement components (C1q, C3, C4, C5, C5a) and other substances that facilitate pain transmission. Additionally, microglia activation can lead to altered activity of opioid systems and neuropathic pain is characterized by resistance to morphine. Pharmacological attenuation of glial activation represents a novel approach for controlling neuropathic pain. It has been found that propentofylline, pentoxifylline, fluorocitrate and minocycline decrease microglial activation and inhibit proinflammatory cytokines, thereby suppressing the development of neuropathic pain. The results of many studies support the idea that modulation of glial and neuroimmune activation may be a potential therapeutic mechanism for enhancement of morphine analgesia. Researchers and pharmacological companies have embarked on a new approach to the control of microglial activity, which is to search for substances that activate anti-inflammatory cytokines like IL-10. IL-10 is very interesting since it reduces allodynia and hyperalgesia by suppressing the production and activity of TNF-alpha, IL-1beta and IL-6. Some glial inhibitors, which are safe and clinically well tolerated, are potential useful agents for treatment of neuropathic pain and for the prevention of tolerance to morphine analgesia. Targeting glial activation is a clinically promising method for treatment of neuropathic pain.

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Microglia: a promising target for treating neuropathic and postoperative pain, and morphine tolerance.

Source

Department of Anesthesiology, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA.

Abstract

Management of chronic pain, such as nerve-injury-induced neuropathic pain associated with diabetic neuropathy, viral infection, and cancer, is a real clinical challenge. Major surgeries, such as breast and thoracic surgery, leg amputation, and coronary artery bypass surgery, also lead to chronic pain in 10-50% of individuals after acute postoperative pain, partly due to surgery-induced nerve injury. Current treatments mainly focus on blocking neurotransmission in the pain pathway and have only resulted in limited success. Ironically, chronic opioid exposure might lead to paradoxical pain. Development of effective therapeutic strategies requires a better understanding of cellular mechanisms underlying the pathogenesis of neuropathic pain. Progress in pain research points to an important role of microglial cells in the development of chronic pain. Spinal cord microglia are strongly activated after nerve injury, surgical incision, and chronic opioid exposure. Increasing evidence suggests that, under all these conditions, the activated microglia not only exhibit increased expression of microglial markers CD 11 b and Iba 1, but also display elevated phosphorylation of p38 mitogen-activated protein kinase. Inhibition of spinal cord p38 has been shown to attenuate neuropathic and postoperative pain, as well as morphine-induced antinociceptive tolerance. Activation of p38 in spinal microglia results in increased synthesis and release of the neurotrophin brain-derived neurotrophic factor and the proinflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α. These microglia-released mediators can powerfully modulate spinal cord synaptic transmission, leading to increased excitability of dorsal horn neurons, that is, central sensitization, partly via suppressing inhibitory synaptic transmission. Here, we review studies that support the pronociceptive role of microglia in conditions of neuropathic and postoperative pain and opioid tolerance. We conclude that targeting microglial signaling might lead to more effective treatments for devastating chronic pain after diabetic neuropathy, viral infection, cancer, and major surgeries, partly via improving the analgesic efficacy of opioids.

 

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The material on this site is for informational purposes only, and is not a substitute for medical advice,
diagnosis or treatment provided by a qualified health care provider.
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For My Home Page, click here:  
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Posted in Chronic Pain, Glia, Neuropathy, Opioid Tolerance, Uncategorized. Tags: , , , . Leave a Comment »

Painkiller Efficacy in 2010 Less Than in 2000

01/28/2012 — Nancy Sajben MD

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This research shows efficacy of analgesics decreasing since 2000.

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“The evidence for pharmacological treatment of neuropathic pain” publication is a good meta-analysis of the current state of evidence-based treatment of neuropathic pain.

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I have quoted extensively from the article as it is important.

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“Abstract: One hundred and seventy-four studies were included, representing a 66% increase in published randomized, placebo-controlled trials in the last 5 years. Painful poly-neuropathy (most often due to diabetes) was examined in 69 studies, postherpetic neuralgia in 23, while peripheral nerve injury, central pain, HIV neuropathy, and trigeminal neuralgia were less often studied. Tricyclic antidepressants, serotonin noradrenaline reuptake inhibitors, the anticonvulsants gabapentin and pregabalin, and opioids are the drug classes for which there is the best evidence for a clinical relevant effect. Despite a 66% increase in published trials only a limited improvement of neuropathic pain treatment has been obtained. A large proportion of neuropathic pain patients are left with insufficient pain relief. This fact calls for other treatment options to target chronic neuropathic pain. Large-scale drug trials that aim to identify possible subgroups of patients who are likely to respond to specific drugs are needed to test the hypothesis that a mechanism-based classification may help improve treatment of the individual patients.”

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~The bla

The black circles are recent circles, the light circles are from the past. Shift to the right means less effect.

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“Fig. 1. It shows the combined numbers needed to treat (NNT) values for various drug classes in all central and peripheral neuropathic pain conditions (not including trigeminal neuralgia). The figure illustrates the change from 2005 values in light grey to 2010 values in dark grey.  [emphasis mine]The circle sizes indicate the relative number of patients who received active treatment drugs in trials for which dichotomous data were available. Please note that the differences in study design and the patient populations preclude a direct comparison of NNT values across drug classes (see text). BTX-A: botulinum toxin type A; TCAs: tricyclic antidepressants; SNRIs: serotonin noradrenaline reuptake inhibitors; SSRIs: selective serotonin reuptake inhibitor.”

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“Fig. 2. It shows the combined numbers needed to treat (NNT) values for different drug classes against specific disease etiologies. The symbol sizes indicate the relative number of patients who received active treatment drugs in the trials for which dichotomous data were available.”

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 A disease-based classification: fact or fiction?

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“Since (1) there are no clear indications that specific diseases should be treated with specific treatments, (2) symptoms and signs overlap in various neuropathic pain conditions [6], and (3) currently available drugs act with unspecific neurodepressant actions rather on pivotal pathophysiological mechanisms, at present there is no good rationale for a treatment algorithm that discriminates between underlying etiologies [45]. Nevertheless, the vast majority of trials have been done in painful diabetic neuropathy and PHN and few, if any, in certain other conditions (e.g. Guillain–Barré syndrome and small-fiber neuropathy), and recommending a treatment for other conditions may seem to be an unjustified jump.”

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“Supplementary Figure 1L’Abbé plot showing pain relief for all drugs for different neuropathic pain conditions. Each point illustrates one comparison against placebo (for trials listed in Supplementary Table 1). The axes indicate the percentage of patients with at least 50% pain relief with active and placebo treatment.© 2010 International Association for the Study of Pain”

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Conclusion

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“Pharmacological treatment still represents the main option for treating chronic neuropathic pain. Our understanding of neuropathic pain-generating mechanisms has grown considerably within the last few decades, but unfortunately this research has not been matched by a similar improvement in treatment efficacy. We are still limited in our efforts in managing neuropathic pain by relying on treating the symptoms of pain rather than identifying the underlying disease mechanisms causing the pain. Although 69 new randomized controlled trials have been published in the past 5years compared with 105 published trials published in the preceding 39years, only a marginal improvement in the treatment of the patients with neuropathic pain has been achieved.”

© 2010 International Association for the Study of Pain

The study is part of the European project, funded by the Innovative Medicines Initiative Joint Undertaking

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The material on this site is for informational purposes only,

and is not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider.

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~

For My Home Page, click here: 

Welcome to my Weblog on Pain Management!

~~

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Posted in Anti-iinflammatory, Antidepressants, Chronic Pain, Neuropathy, Opioids, Pain Management, medicine, Research, Uncategorized. Leave a Comment »

RSD – Complex Regional Pain Syndrome – A Case Report

03/03/2010 — Nancy Sajben MD

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Rational Polypharmacy

Naltrexone is a remarkable drug for intractable pain

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I first saw this RN in June 2006.

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She is now 60 years old.  She was an OR scrub nurse for almost 30 years, but was disabled for the last 5 years before seeing me. She had Reflex Sympathetic Dystrophy [RSD] of both legs with “arthritis” of the feet/ankle that felt like she was “90 years old” with cold allodynia. Allodynia is pain from a stimulus such as light touch or a breath or air that is not normally painful. Imagine a light touch that feels like severe nerve pain, one of the most disturbing pains a person could have. The temperature of her feet was 81 degrees, hands 92 degrees.

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Pain of both feet felt like a vise grip, gnawing, penetrating, “like broken bones in the feet,” variable at different times but always worse as the day progressed, with a crushing sensation that penetrated through foot and ankle. She was unable to tolerate socks or anything on her feet after 5 pm, unable even to tolerate air on the area, unable to tolerate coolness below waist, but felt hot above waist. She wore a blanket and covers on the hottest 120 degree days, and forced herself to tolerate touch at the legs in order to desensitize them, as we instruct patients to do. She felt constant tingling numbness of the soles of feet for 3 years, with weakness, stiffness “almost solid” like a block. Spasm in soles of feet had resolved the last 6 months before seeing me.

Pain ranged from 2 to 9 on a scale of 10, where 10 is the worst pain imaginable, worst after 5 pm. Average pain was 3. It interfered with sleep at times, and she used a tented frame to keep blankets off her feet, preheated the bed to avoid any coolness, and avoided cold under all circumstances. In the morning, the joints felt like she had a broken ankle. She would massage the feet with lotion, put on alpaca socks, and slowly begin to walk. Then tried to mobilize the joints. Walking made pain worse though walking had always been a favorite activity.~

Before seeing me she had had more than 10 sympathetic blocks, was hospitalized 11 days due to headache from prednisone 60 mg that had been trialed to relieve her pain. She had been prescribed Procardia to relieve the “vascular” disease that she did not have but the drug led to gangrene of the gall bladder; she had been prescribed almost every “adjuvant” used to relieve pain and as much as 9 grams of Neurontin daily, all of this to attempt to relieve the severe pain in her legs and feet.

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This is how she got better

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When I first saw her in 2006, I prescribed low dose oral ketamine that gave relief lasting up to 3 hours from each dose. She then requested referral to Dr. Schwartzman, chief of neurology at Drexel University in Philadelphia, for continuous 5 day ketamine infusion that was done May 2007. She was pain free but it completely lost effect after 8 months, despite booster infusions every 4 to 6 weeks for 4 hours daily over 2 days during those 8 months. After insurance the cost out of pocket was $45,000 in 2007 alone. Dr. Schwartzman had nothing more to offer after it failed and said most patients have relief for less than 6 months if at all.

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In March 2007, I started her on a combination of Namenda 55 mg daily with lamotrigine 350 mg daily that relieved 90% of the pain, but once every 6 to 8 weeks she needed 12.5 to 25 mg low dose oral ketamine for breakthrough pain. Even more rarely, she used oxycodone 10 to 20 mg.

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In October 2008, adding naltrexone 1 mg by mouth, she became pain free. Since then she has not needed anything for breakthrough pain and on 3/5/09, she reported that her last use of ketamine and oxycodone occurred with the addition of low dose naltrexone.

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In 2009, she hiked 30 miles down the Grand Canyon and back up in 3 days.

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Naltrexone was later increased to 4.5 mg as she completely tapered off lamotrigine.

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By December 2009, the RSD was 98% better and she reported that it was not pain anymore. Medications then were naltrexone 12.5 mg at bedtime and Namenda 55 mg daily in divided doses. She had just a “remnant” of a little buzz, but no crushing except when active, late in the day.

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A few months later she slowly tapered off Namenda with no increase in pain; and in October 2010, on my advice she tapered naltrexone 12.5 mg from daily to every third day. There has been no increase in pain but she is reluctant to discontinue naltrexone for fear that RSD may recur.

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She hikes 2 miles 3 to 4 times a week, does Iron Mountain once a week, does “Silver Sneekers” exercise 1 hour 3 times a week and sleeps well 8 to 10 hours a night without a sleeping pill.

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She remains on low dose naltrexone as her sole medication for this

previously disabling neuropathic pain syndrome~

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She has returned to part time work and spends a few weeks a month traveling the world, hiking, volunteering, sightseeing.

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Research funding is needed to view whether we can detect

activated glia in the spinal cord, as discussed here.

If there are no signs of activated glia, she may feel reassured that the condition has resolved.

Naltrexone is an immune modulator.

The site of action of naltrexone is at the Toll-like receptor (TLR4) attached to the cell surface membrane of glia.

The ability to view activated glia would help greatly in treatment of so many conditions including neuropathic pain.

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Naltrexone

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I have found that naltrexone is a remarkable medication for various pain conditions, and going through the steps of rational polypharmacy may be very rewarding for some patients though at times it may work all on its own. It has caused me to completely reassess how I approach the treatment of intractable pain – not just RSD or CRPS but arthritis, sciatica and various forms of mechanical pain. And it has led to further changes in the timing and dosing of naltrexone based upon the experiences patients have reported back to me over the years. It is hoped that further research will lead to better understanding of how naltrexone acts upon pain pathways. Surprisingly we already know quite a fair amount.

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My deepest gratitude to Dr. Jau-Shyong Hong, Chief of Neuropharmacology at NIH, whose many generous discussions, emails and research publications have helped me to understand it’s profound anti-inflammatory effect in the central nervous system through its actions on microglia. I previously posted a discussion of mechanisms of naltrexone and dextromethorphan in greater detail here. Naltrexone and dextromethorphan are classified as morphinans, morphine-like. They suppress Superoxide, a free radical that destroys neurons which may cause or contribute to Alzheimers and Parkinsons Disease. That research goes back to the late 1980′s and continues to grow. Phase II studies with morphinans are now being done on those conditions. Studies are also going on now with naltrexone/Wellbutrin combination for weight loss. The drug is called Contrave, from Orexigen Therapeutics Inc. and the dose I believe is 32 mg naltrexone – I do not know how they decided upon that dosage.

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In my experience, naltrexone is a very benign drug at these low doses, though colleagues who prescribe 400 mg for the FDA approved use at that high dose may see some liver toxicity. I always begin at 1 mg or 4.5 mg, depending upon whether or not the patient is a slow drug metabolizer, i.e. may lack one of the CYP P450 chromosomes for metabolizing drugs. I have long suspected it also has an effect on the hypothalamus because a few patients with profound postmenopausal hot flashes have reported that is no longer a problem and that their husbands simply cannot believe the bonus, and this may explain the effect upon appetite that Orexigen has found. At higher doses than I generally use there may be some constipation which is treatable. It may cause vivid dreaming in some, and a small percentage may have insomnia for a few days. Pharmacology and safety is discussed here.

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Stay tuned. I’ll be adding more case reports of different pain conditions in the near future. They are truly fascinating. It has changed my entire approach to treating pain.

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Cost

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Wouldn’t it be nice if NIH funded more for pain research? Imagine how much money that would save the country and save the lives of each person with disability who could recover? As I posted here, the American Pain Society has shown that NIH spends 0.67% of its budget on pain research – less than 1% – though 10 to 20% of the population in the US suffers from chronic pain, an estimated 60 million Americans, and pain conditions are more prevalent among the elderly.

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I am told by my pharmacist that perhaps 70% of the time insurance will approve coverage for compounded low dose naltrexone. It is very affordable but some insurance carriers deny payment for naltrexone. Medicare will not pay for compounded medication either. Compare this low cost compound to the wholesale price for 100 tablets of Oxycontin, $1300, which may not be relieving pain – then multiple that by 2 or 3 each month for one patient. Imagine if the $22 billion of federal money for health insurance technology, for software which is untested and will expire in a few years, instead went into NIH funding for pain research. What a lovely thought. 

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The material on this site is for informational purposes only, and

is not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider.

~

For My Home Page, click here:  Welcome to my Weblog on Pain Management!

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Posted in Complex Regional Pain Syndrome, CRPS, Ketamine, Low Dose Naltrexone LDN, Naltrexone, Namenda, Neuropathy, RSD, Weight Loss. Tags: , , , , , , , , , , , , , , . 24 Comments »

Ketamine

05/26/2009 — Nancy Sajben MD

Ketamine for persons with severe pain

cancerIn special circumstances, I may suggest a trial of low dose oral ketamine. It is formulated by a compounding pharmacist as an oral suspension. It is safe to use without significant adverse effects, though you may experience transient symptoms lasting 20 to 40 minutes after the first few doses. For most people, it may relieve pain when all other methods have failed, possibly including total pain relief with no side effects in patients who have then been able to discontinue all opioids.

Keep all your medicine, opioids and ketamine, in a lock box to prevent abuse by others. This is a Schedule III drug like Vicodin.

Achieving control of chronic pain requires a partnership

based upon trust and effort

Requirements: I will work closely with you on ketamine and ask you to keep a log of pain before each dose and 30 minutes after. In addition, for the first week I ask that you log blood pressure and heart rate before each dose and 30 minutes after. This requires that you see me in the office one week later. If you have any questions or problems, I ask that you call me the same day, whether it be weekend or holiday. If you are unable to keep these logs before and after the dose, and the appointment one week later, the trial will be discontinued. You have no authority to continue without my consent.

Blood Pressure: Usually no change occurs in blood pressure. Some have reported that ketamine lowers their blood pressure and they are lightheaded when they stand up. If your blood pressure drops or if you are lightheaded, be very cautious as that may lead to fainting and brief loss of consciousness. Anytime a person faints, that could result in potentially serious injury such as hip fracture, other fractures, bleeding or brain injury if you strike your head. Your blood pressure should be above 100 when standing.  Ketamine has been reported to increase blood pressure and pulse, but I have not found that to occur with these doses.

Side Effects: Ketamine has a very narrow therapeutic window for pain control. This means that once you find the dose that relieves pain, a very slight increase in dose may produce intolerable side effects. Unfortunately some patients reach a dose that produces side effects before they experience any pain relief.

Most patients have no side effects with the low doses used by this protocol, though some may have mild symptoms lasting up to 40 minutes. If you do, then try decreasing the dose a small amount.

It is possible but rare that you may experience severe, frightening hallucinations or may feel you are outside the body observing it do things, called a dissociative reaction.

These side effects are dose related and have been short lasting, usually no longer than 40 minutes.  The antidote is Ativan.

Steps to follow: Read all steps carefully before you begin

  • Take ketamine 30 minutes prior to your other pain medication
  • For the first dose, remain seated or lie down for 20 minutes after you take the dose to avoid risk of falling. Do not take the dose and walk around.
  • A few persons have had severe imbalance lasting 10 or 20 minutes. This has resolved after the first few doses in those persons. It may not happen to you, so test with caution. If it has not occurred at the first dose, it is unlikely to occur at all.
  • Follow the dosing guidelines in the log I give you and which I repeat in this next step:
    Begin with 0.25 mL and increase by increments of 0.25 mL every 6 hours or longer than 6 hours, until you have some pain relief. Do not increase that dose or dosing interval.

Example: begin 0.25 mL, then 0.5, next 0.75, 1.0, 1.25, 1.5, 1.75, 2.0

If you have had no effect on pain by 2.0 mL, schedule an appointment for further instructions.
If your pain decreases only 1 or 2 points, that is your dose.  It will NOT get better by increasing the dose.  Stop increasing.

  • If you have intolerable side effects, you may use 1 or 2 Ativan tablets immediately as an antidote, and every 30 minutes, up to 5 of them.
  • CAUTION: Be alert to the opioid-sparing effects of ketamine!

This means that if ketamine relieves your pain, you do not need to take the opioid as that would be an opioid overdose and may cause serious side effects.

Reduce or temporarily stop your opioid medication if pain is gone after using ketamine.

This is why you take ketamine 30 minutes before the opioid. Some people have been able to completely stop all opioid medication due to pain relief from ketamine alone.

  • CAUTION: Do not drive for 6 hours after a dose.

This is for the protection of you and others. You may not be aware of very subtle side effects.

  • You may take a dose every 6 hours, or longer than 6 hours. Less is more.

If ketamine loses its effect, stop use for 2 or 3 days, then resume. It can be a fickle drug.  That is why increasing the dose causes loss of effect.

Some take ketamine only before sleep. If you do that, use it 30 minutes before sleep in order to log its effect and take blood pressure/pulse before and after. Continue this initially until further changes are approved.

Ketamine was approved for use as an anesthetic by the FDA in 1970

TibetanBluePoppy-fullIt’s use for pain is “off label” as it was approved only in high doses for anesthesia. It has been used safely in babies. Unlike opioids, it does not depress breathing or bowel function, and usually does not depress cardiovascular function. Since the late 1980′s, numerous scientific articles have been published on its use as a third line choice for some pain conditions; there are few double blind control studies, one is listed below. If you search ketamine on various internet search engines you find it is abused by addicts just as other drugs are. You find medical articles when you search the literature using  Google Scholar or PubMed in the National Library of Medicine. If you find a medical article with adverse effects, let me know. I have spoken to leading brain and psychiatric researchers who have verified there are no lasting side effects from its use.

Many publications on ketamine use multi-day infusions at much higher dosages than the oral dosages in my protocol. Drexel University has treated over 3,000 patients with infusions of 40 mg/hour for 5 days with no lasting adverse effects. Even higher doses than that are used for surgical anesthesia. Ketamine is a powerful tool for treating pain.

Medical Publications


You can click and download each reference in blue below

High dose ketamine improves neurological outcome after stroke in rats, Reeker et al, Canadian J Anesth 47:572-578, 2000

Ketamine, Pasero C, McCaffery M, Amer J Nursing, 105:60-64, 2005
An excellent review, more clinical, easier to read than some more technical papers

Ketamine in Chronic Pain Management: An Evidence Based Review, Hocking & Cousins, Anesth Analg, 97(6):1730-1739, 2003 This nine page article is the best comprehensive review of ketamine’s use in almost every known pain condition including post stroke pain.  Easier to read; a catalogue of pain syndromes and references.

Ketamine Stops Aura in Familial Hemiplegic Migraine, Neurology, 55:139-141, 2000 Two mechanisms may account for this. First, ketamine can increase cerebral blood flow, which may counteract the marked hypoperfusion induced by cortical spreading depression, as observed in migraine with aura. Second, in experimental animals, ketamine accelerates the  restitution of neuronal function after hypoxia.

Ketamine oral use in 8 chronic pain patients, Canadian J. of Anesthesia, 2004


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The Reflex Sympathetic Dystrophy Association library has many articles on RSD, CRPS and ketamine. Remember most of the articles are written for scientists and physicians.

From their library I particularly recommend the first article, below.  The last two are very technical but important new research.


Expectations of Pain: I Think, Therefore I Am, Jones-London M, National Institute of Neurological Disorders and Stroke

For pain mechanisms, read
Beyond Neurons: Evidence that Immune and Glial Cells Contribute to Pathological Pain States, Watkins L and Maier SF, Physiology Review. 2003;82:981-1011.

For pain mechanisms, read
Complex Regional Pain Syndrome (CRPS): Evidence of focal small-fiber axonal degeneration in complex regional pain syndrome-I (reflex sympathetic dystrophy),  Oaklander AL et al., Pain. 2006;120:235-243.

There is no link to the following double blind controlled research publication:

Mercadante S, Arcuri E, Tirelli W, Casuccio A. Analgesic effect of intravenous Ketamine in cancer patients on morphine therapy: a randomized, controlled, double-blind, crossover, double-dose study. J Pain Symptom Manage 2000;20:246-252. Mercadante et al compared intravenous infusions of Ketamine (0.25 and 0.5 mg/kg) with placebo in a double-blind, crossover study of 10 cancer patients with neuropathic pain.

Please note that the free Adobe Acrobat Reader is needed to read some references.

You can download the free reader now.

~~~~~The material on this site is for informational purposes only, and is not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider. ~~~~~

Posted in Back Pain, Chronic Pain, Complex Regional Pain Syndrome, CRPS, Failed back surgery, intractable pain, Ketamine, Medications, Neuropathy, Pain Management, medicine, Radiculopathy, RSD, Sciatica. Tags: , , , , , , . Comments Off
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