SNX-111, administered intrathecally by continuous, constant-rate infusion, produced dose-dependent pain relief in a 43-year-old male patient with a 23-year history of intractable deafferentation and phantom limb pain secondary to brachial plexus avulsion and subsequent amputation. Dizziness, blurred vision, and lateral-gaze nystagmus were dose-dependent side effects that resolved with decreasing dose levels. Complete pain relief was achieved in this patient without side effects after dose adjustment. We conclude that SNX-111 is a potent analgesic, antihyperesthesic, and antiallodynic agent. Controlled studies of SNX-111 in patients with malignant and nonmalignant pain syndromes are warranted and are under way.

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Three patients with terminal malignancy reporting ineffective analgesia using systemic and subsequently spinal opiates were treated with subcutaneous infusion of 10% lidocaine hydrochloride. During the infusion, reasonably stable blood concentrations were achieved and maintained using a subcutaneous infusion at varying dose rates over days to months with improvement of the pain complaints which continued to be refractory to conventional analgesics. Blood lidocaine levels obtained at regular intervals revealed effective concentrations between 2 and 5 micrograms/ml for each patient.

Chronic pain is an emotional experience and is defined as pain lasting greater than six months. It is important to understand the neurophysiology of pain in order to treat it. Nociceptors in the periphery travel to the substantia gelatinosa of the spinal cord while secondary and tertiary afferents transmit information from the dorsal horn to the brain. Modification of pain information may take place in these ascending pathways or in descending pathways. Treatment of chronic pain is most successful when it is approached in a multidisciplinary fashion with the focus not only on treatment of underlying etiology, but also on the secondary impacts of pain on the patient's life. The management of chronic pain requires special expertise. Most of the experts in chronic pain assessment and management organize themselves into pain treatment centers. These centers vary widely in their approach to the problem. The most sophisticated is a multidisciplinary center that is university-based and includes teaching and research. Treatment of chronic pain includes a variety of medications, psychological support, and rehabilitation. Multidisciplinary pain management is also an integral part of the palliative care and hospice concept used to treat cancer pain.

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The relationship between visual analog pain intensity and pain relief scores changed systematically during both analgesic drug studies. The authors hypothesize that patients' interpretation of the pain relief scale had changed during the studies and therefore suggest using the pain intensity scale to quantify analgesic drug action over time.

Pharmacokinetic parameters for lidocaine were derived and administration was prospectively tested via computer-controlled infusion pumps for patients with chronic neuropathic pain. The estimated parameters performed well when tested prospectively. A second estimation step further refined the parameters and improved performance, as measured using internal cross-validation.

Intravenously administered dynorphin A(1-13) is very rapidly metabolized, on the basis of the time course of immunoreactivity in the blood. Long-term opioid therapy did not influence either the pharmacokinetics or incidence of side effects.