[Balanced spinal analgesia in the treatment of oncologic pain. Review of the literature].

Certain types of cancer pain fail to respond well either to systemic drug therapy or to spinal opioids because of the occurrence of intolerable adverse effects. In addition to spinal opioids other drugs may produce an antinociceptive effect when administered by the spinal route, such as local anesthetics, NSAID, alpha 2-agonists, calcium-channel blockers, NMDA antagonists, cholinergic drugs, peptides such as somatostatin, octreotide or calcitonin, adenosine agonists, benzodiazepines, neurokinin and cholecystokinin antagonists, nitric oxide synthase inhibitors, corticosteroids, and enkephalinase inhibitors. All these drugs may be administered in combination between them, realising the so called balanced spinal analgesia. The aim of this study is to analyse: the available methods for the evaluation of pharmacological interactions, the types of interaction between different spinal antinociceptive drugs and the role of balanced spinal analgesia in the treatment of cancer pain. Analysis of the presented data shows that the spinal synergism between opioids-local anesthetics and opioids-alpha 2-agonists can be useful in the treatment of opioid refractory cancer pain. Furthermore, the use of cholinergic drugs combined with opioids and alpha 2-agonists may be promising. Finally, even if the synergism between NSAID or NMDA antagonists with opioids or alpha 2-agonists have been proved, at the moment their use in man by the spinal route is not advisable because of the absence of adequate studies on their neurotoxicity and adverse effects.