Addiction to the opioids. Consequences on the pain treatment

Addiction is a chronic disease of the central nervous system. Numerous neuroadaptations occur following chronic exposure to drugs of abuse. The progress in numerous domains, neuroimaging, molecular biology, animal models, allowed these last years to understand better the neurobiological and neurochemical mechanisms of addictions. The activity of the central nervous system is globally regulated by excitatory and inhibitory ligands. The very fine balance which exists between these two groups of neurotransmitters and neuropeptides allows maintaining the equilibrium of the brain. The acute drug exposure is strongly destabilizing this balance. If the exposure is repeated, the brain is going to try to oppose to these effects to maintain the balance. We have neuroadaptations of the brain. These mechanisms, which are mechanisms of re-equilibrium, are relatively stable, and explain the necessity of using pharmacotherapy to help in the abstinence. The maintenance treatments in the management of opioid dependence showed its utility during the last years, with a reduction of the consumption of opiates as well as to a decrease of the rates of morbidity and mortality bound to the taking of drugs. Nevertheless thesemaintenance treatments are opioid agonists (buprenorphine or methadone), with specific pharmacodynamic and pharmacokinetic properties. Adequate treatment of painful conditions is an essential dimension of quality medical care. Physicians will frequently encounter patients receiving agonist therapy treatment with methadone or buprenorphine and who develop acutely or chronically painful conditions, requiring effective treatment strategies.