“ Controversie sulla diagnosi e terapia del dolore neuropatico ” Opinioni a confronto. Gli oppioidi sono indicati nel dolore neuropatico ? NO . Marco Lacerenza Medicina del Dolore Fondazione “Opera San Camillo” Casa di Cura S. Pio X, Milano.
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“Controversie sulla diagnosi
e terapia del dolore neuropatico”
Opinioni a confronto
Medicina del Dolore
Fondazione “Opera San Camillo”
Casa di Cura S. Pio X, Milano
Palermo, 29-30 novembre 2012, Reale Albergo delle Povere
Dolore - Sofferenza
“Tra i rimedi che
Dio Onnipotente ha voluto, bontà Sua, dare all’uomo per alleviare
le sue sofferenze, nessuno è universale
ed efficace come l’oppio.”
Thomas Sydenham, 1624-1689
Sumeri: IX secolo AC: oppio la pianta della gioia
Omero, IV libro Odissea :….“Nel dolce Vino, di cui bevean, farmaco infuse contrario al pianto e all'ira, e che l'obblìo seco inducea d'ogni travaglio e cura”.
ROLES IN VIVO
Distinctroles in hedonichomeostasis and emotionalcontrol
Individuals with high reward responsiveness, a personality trait dependent on the endogenous opioid neurotransmission, experience more exogenous opioid-induced behavioral analgesia.
Emergingevidencesuggests that MOR polymorphism could contribute to variability in behavioral opioid analgesia by introducing variability of the MOR responsiveness to exogenous opioids.
It is possible that trait RWR and the neuronal response to noxious stimuli in the endogenous opioid-rich brain reward circuitry could be useful endophenotypes of behavioral opioid analgesia.
Corteccia cingolata anteriore, C.prefrontale, strati superficiali della corteccia cerebrale
Nuclei della base, talamo, amigdala,
PAG, RMN, reticolare del tronco
Corno posteriore midollare:
Periferia: nocicettori e afferenti viscerali
Oppioidi: Meccanismi d’azione
Blocco ingresso ioni Ca++
Fuoriuscita di ioni K+
Fuoriuscita di ioni K+
Modificata da: A.H.Dickenson, 2000
I recettori per glioppioidi
I recettori per glioppioidi: binding
Perché funzionano poco????
Nerve-injury neuropathy and Diabetic Neuropathy:
Functionaldownregulation and/or desensitizationof μ-opioid receptors in the dorsal horn of the spinal cord (but not a significant decrease in number) may be related to increased production of PKC .
May be due to: activation of NMDARs in postsynaptic cells,
to an autophosphorylation of the TrkB receptor by BDNF.
In fact, the development of the hyperalgesia and allodynia in NP states is suppressed by
administration of NMDA receptor antagonists,
TrkB/Fc chimera protein (sequesters endogenous BDNF)
Dolore Neuropatico: Meccanismi che portano alla desensitizzazione di MORs
Ridotta efficacia nella pratica clinica
Pain that has become more diffuse and less defined in quality and has a wider spatial distribution than the pre-existingpain.
NMDA receptors become activated and when inhibited, prevent the development of tolerance
The glutamate transporter system is inhibited,
(increasing the amount of glutamate available to NMDAR)
Ca regulated intracellular PKC is likely a link between cellular mechanisms of tolerance and OIH
Prolongedmorphineadministrationinducesneurotoxicityvia NMDA receptor mediated apoptotic cell death in the dorsal horn
Smith HS, 2012
Il risveglio americano dall’oppiofobia
“Opioidmaintenancetherapy can be a safesalutary and more humanealternative…..in thosepatientswithintractablenon-malignantpain and non historyofdrugabuse”
The dichotomous classification of nociceptive and neuropathic pain is not yet fully recognized in the pain literature or among physicians dealing withpain.
..comonnarcoticanalgesics, administered in a double-blind fashion and in doses which effectively control acute and
chronic nociceptive pain, are inefficient for relief of neuropathic (including deafferentation) pain…..
The reason ………..isunknown.
Opioids for neuropathic pain (Review), 2009
Eisenberg E, McNicol ED, Carr DB
Short-term studies: equivocal evidence regarding the efficacy of opioids in neuropathic pain.
Intermediate-term studies demonstrated significant efficacy of opioids over placebo for neuropathic pain.
The difference in outcomes does not support the use of short-term opioid administration as a predictive tool to decide whether to initiate intermediate-term opioid therapy.
…the participants in the included studies may not reflect those commonly seen in practice. Therefore, issues such as abuse of medication, or conversely, non-compliance due to participants’ unwillingness to tolerate side effects may not be accurately reflected in our results.
The meta-analysis of Martell et al. 2007 identifies also a number of relevant issues:
patients were more likely to be prescribed opioids if they reported greater distress and suffering.
The prevalence of substance abuse disorders was in the range of 40% to 50% in these patients and up to 24% showed aberrantmedication-takingbehaviour
Long-term trials of opioid efficacy for chronic back pain are lacking, and there is other evidence that indicates that the long-term efficacy of opioids for chronic pain may be limited
Opioids and opioid combinations were exceeding NSAIDs in proportion of patients and number of prescriptions.
Short-acting opioids are frequently used as rescue medication…. high prescribing..(36.5%). Although the frequency of use of long-acting opioids was low (3.8%), the median (7.0) number of prescriptions were higher than for any other medication.
Opioids continue to be recommended and used, despite evidence of a negative association with outcomes in CLBP, including function and productivity and an increased likelihood of substance use disorders.
In such“pathological pain states”, nociception is not the sole target, but also suffering, dysfunction, mood states, psychosocial factors and dependence on the health system. Then opioid use is less likely to improve analgesia and even less to yield psychological or functionalimprovement.
Several investigations have identified drug abuse in 18%
to 41% of patients receiving opioids for chronic pain.36-40 The prevalence of lifetime substance use disorders range from 36% to 56%, with an estimate of 43% current substance use disorders and 5% to 24% of the patients with aberrant medicationtakingbehaviours.
Fattori di Rischio per l’Abuso e la Dipendenza
Storia di abuso di sostanze
Storia di dolori multipli
Prescrizioni di > 90gg
Valutazione dolore, QoL, funzionamento
Spiegazioni esaustive dei rischi
A breve e lungo termine
Unintentional overdose death related to an opioid analgesic
9 persons are admitted for substance abuse treatment
35 visit ER
161 report drug abuse or dependence
461 report nonmedical uses of opioid analgesics
It has been shown that from 1997 through 2007, there was a seven fold increase in the number of prescriptions foropioids.
The pharmaceuticalindustryaggressivelymarketed long-acting opioids for chronic pain relying on 2 erroneous facts:
That medical management with opioids is the recommended solution for undertreated chronic pain
That the use of long-acting formulations decreases incidences of prescription opioid abuse.
The principles of opioid management in acute pain and cancer pain were transferred to the chronicpain arena.
JAMA 2000, 283: 1710-1714: ”Increasedopioid use is not associated with deleterious healthconsequences”.
Approximatelytwo-thirdsofthe panel responsible for writing guidelines for the use of opioids for chronic pain for the American Academy of Pain Medicine (AAPM) and American Pain Society (APS) had conflicts of interest with the opioid pharmaceutical industry.
The investigationannouncedby the Senate in reference to conflicts of interest in preparation of opioid guidelines and promotion of opioid usage, have resulted in abandonment of the American Pain Foundation on May 10, 2012, which was a pivotal organization in promoting opioid use.
Rischi del trattamento con oppioidi nel lungo termine:
Sviluppo di tolleranza
Iperalgesia indotta da oppioidi
Abuso e Dipendenza
Ipogonadismo (Disfunzioni sessuali, osteoporosi, depressione, fatica)
Alterazioni del sistema immunitario (attraverso il sistema ipotalamo-ipofisi-surrene)
riduce la produzione di anticorpi
riduce l’attività delle cellule Natural Killer
riduce l’espressione di citochine
riduce l’attività fagocitaria
Opioidusefor the management ofpain in fibromyalgiaisstronglydiscouraged and isnotrecommendedbyanycurrentguideline.
women couldbe at higherriskfor the negative medicaland psychologicaleffectsofopioidsbecausetheyhavemore persistentpainthanmen, and maybeprescribedopioidsmore often and at higherdosesthanmen
multiple psychophysiologicalfactorsmaycontributetocertainrisks and consequencesofchronicopioidtherapy
risksin pregnancy and breast-feeding
asin men, risksthat are uniqueto women mayincreaseconcomitantlywithgreaterexposuretoopioids(in termsoffrequency and dosage)
asin men, risksfor women appeartovary at differentages.
GRAZIE PER LA VOSTRA ATTENZIONE