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Hidden Metabolic Drivers of Pain. Dr Marc A. Russo MBBS DA FANZCA FFPMANZCA FPM Spring Meeting 2010. Traditional Pharmacology. Proven efficacy as single agent in controlled animal studies. All other variables kept the same. Often 80-100% reduction in outcome.

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Hidden metabolic drivers of pain

Hidden Metabolic Drivers of Pain

Dr Marc A. Russo

MBBS DA FANZCA FFPMANZCA

FPM Spring Meeting 2010


Traditional pharmacology
Traditional Pharmacology

  • Proven efficacy as single agent in controlled animal studies. All other variables kept the same.

  • Often 80-100% reduction in outcome.

  • Why do we see 10-40% reduction in clinical practice?


Why do our drugs work so poorly
Why do our drugs work so poorly?

  • Non controlled conditions, compliance

  • Diet, sleep, mood variability

  • Multiple drugs

  • Multiple different genetic strains of human


Areas to be reviewed
Areas to be Reviewed

  • ATP sensitive Potassium Channel

  • Nitric oxide signaling system

  • Magnesium

  • Drug efflux pump

  • Vitamin B12



K channel
K Channel

  • Channel must be open for G protein coupling to mu opioid receptor

  • Closed channel inhibits opioid induced antinociception

  • High BSL, diabetic drugs close channel



  • Cholesterol blocks the channel independent of the K channel.

  • Lee SY Cholesterol inhibits M-type K+ channels via protein kinase C phosphorylation in sympathetic neurons J Biol Chem 2010 Apr 285(14) 10939-50

  • Level required in patch clamp corresponds to serum level of 6.0 mmol/L


Nitric oxide reactive oxygen species
Nitric Oxide, Reactive Oxygen Species independent of the K channel.

  • Morphine inhibits super oxide dismutase (SOD)

  • More super oxide combines with nitric oxide to form peroxynitrite which disrupts pre and post opioid receptor synaptic function

  • Salvemini D Peroxynitrite: a strategic linchpin of opioid analgesic tolerance Trends in Pharmacol Sci 2009 Apr 30(4) 194-202

  • End result: Opioid Tolerance


Reversing nitroxidative stress
Reversing Nitroxidative Stress independent of the K channel.

  • Cox-2 inhibitors

  • Vitamin C

  • Allopurinol (xanthine oxidase)

  • GTN, nicorandil


Magnesium the ubiquitous ion
Magnesium – The Ubiquitous Ion independent of the K channel.

  • Multiple roles in regulation in the body

  • Serum levels do not well reflect body tissue stores except at extreme low levels


Poster iasp montreal 2010
Poster IASP Montreal 2010 independent of the K channel.

  • 50% of CRPS patients were magnesium deficient as defined by an inadequate urinary excretion of magnesium compared to healthy controls after an IV magnesium load.

  • Does this explain the failure rate of IV Ketamine infusions in treating CRPS?

  • Could one Mg load in CRPS patients prior to commencing ketamine infusion improve outcomes?


Mg deficiency
Mg Deficiency independent of the K channel.

  • Serum magnesium levels below 0.85mmol/l associated with systemic inflammatory response

  • Nielsen FH Magnesium,Inflammation and Obesity in chronic disease Nutrit Rev 2010 Jun 68(6) 333-40


Magnesium and pain
Magnesium and Pain independent of the K channel.

  • Magnesium blocks the development of morphine tolerance

  • Habibi-Asl B Development of morhpine induced tolerance and withdrawal symptoms is attenuatedby lamotrigene and magnesium sulphate in mice Pak J Biol Sci 2010 May 15 12(10) 798-803


P gylcoprotein
P-Gylcoprotein independent of the K channel.

  • Acts as a drug efflux pump

  • Normally acts as an extrusion mechanism for removing intracellular debris

  • Can be upregulated by contact with drugs thus leading to multidrug resistance


  • Prednisone is one of the major activators of the drug efflux pump

  • Dilger K Identification of budesonise and prednisone as substrates of the intestinal drug efflux pump P Glycoprotein Inflammat Bowel Dis 2004 Sep 10(5)578-83

  • Clinical Corollary: Once on steroids your drugs won’t work well

  • This can be reversed by Sulfasalazine increasing glucocorticoid receptor expression

  • Oerlmans R Ann Rheum Dis 2007 Oct 66(10) 1289-95


In the clinic
In the Clinic pump

  • Don’t do lots of steroid blocks close together. You will make the patient refractory to their benefit.

  • Use Sparingly


Vitamin b12
Vitamin B12 pump

  • 26% of >65 year olds have evidence of peripheral neuropathy, rises to 54% in age>85

  • Loss of ankle reflex, fine touch discrimination

  • OR >2 for Vitamin B12 deficiency, Rheumatoid Arthritis, Diabetes Mellitus

  • Mold JW The prevalence, predictors and consequences of peripheral sensory neuropathy in older patients J Am Board Fam Pract 2004 Sep/Oct 17(5) 309-18


Vitamin b121
Vitamin B12 pump

  • Is an antineuropathic drug!

  • Reduced tactile allodynia in a spinal nerve ligation model in dose dependant manner.

  • Granados-Soto V Proc West Pharmacol Soc 2004 47 92-4


Human data
Human Data pump

  • 7 RCTs with positive effects on diabetic neuropathy.

  • Pain and paraesthesia improved

  • Acta Neurol Taiwan Effectiveness of Vtamin B12 on diabetic neuropathy:systematic review of clinical controlled trials 2005 Jun 14(2) 48-54


In the clinic1
In the Clinic pump

  • In a patient with neuropathic pain should an empirical trial of Vitamin B12 be considered?

  • If not should B12 level be measured with a trigger for supplementation?


Other investigational areas
Other Investigational Areas pump

  • Visceral anticholinergic pathway (vagus) – meditation, nicotine

  • Gut inflammation – probiotics

  • Brain inflammation – tryptophan

  • Vitamin D3


In summary
In Summary pump

  • Things are much more complex than one realises.

  • Drug trials really do have to be done on an individual basis – you never can tell.



In the clinic2
In the Clinic pump

  • Consider:

  • Cholesterol, Testosterone, 25OH Vitamin D, Vitamin B12, Magnesium

  • Aim hsCRP<1mg/L ???


If all else fails
If All Else pump Fails

ENCOURAGE A

HEALTHY

LIFESTYLE


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