Articles of interest in other scholarly journals

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A comprehensive review of opioid-induced hyperalgesia

Lee M, Silverman SM, Hansen H, Patel VB, Manchikanti L. Pain Physician 2011; 14:145-161

In this review of opioid-induced hyperalgesia, it is suggested that this phenomenon may result from neuroplastic changes in the peripheral and central nervous system that lead to sensitisation of pronociceptive pathways from central glutaminergic system, spinal dynorphins, descending facilitation and decreased re-uptake and enhanced nociceptive response. NMDA receptors, glutamate transporter system and protein kinase C may be involved. It should be suspected when the effect of opioids decrease in the absence of disease progression, particularly if found in the context of unexplained pain reports or diffuse allodynia and increased levels of pain with increasing dosages. The treatment involves reducing the opioid dose, or NMDA blockade.

Pregabalin for peripheral neuropathic pain: a multicenter, enriched enrollment randomised withdrawal placebo-controlled trial

Gilron I, Wajsbrot D, Therrien F, Lemay J. Clinical Journal of Pain 2011; 27(3):185–193

Neuropathic pain randomised controlled trials of pregabalin have involved primarily diabetic peripheral neuropathy (DPN) and postherpetic neuralgia (PHN). This multicentre trial evaluated pregabalin in a broader range of neuropathic pain etiologies. In this enriched enrolment randomised withdrawal trial, 256 patients received single blind, flexible dose pregabalin for 4 weeks. Of those patients,165 had a 30% pain improvement and 157 were randomised and treated, double blind, to either continue pregabalin (n=80) or to receive placebo (n=77) for 5 weeks. At the double-blind endpoint, mean pain scores were 2.9 (1.9) in the pregabalin group and 3.5 (1.7) in the placebo group (P=0.002).

A Strategy for Conversion From Subcutaneous to Oral Ketamine in Cancer Pain Patients: Effect of a 1:1 Ratio

Benítez-Rosario MA, Salinas-Martín A, González-Guillermo T, Feria M. Journal of Pain and Symptom Management 2011; 41 (6):  1098-1105

The 29 patients who responded to subcutaneous (s.c.) ketamine injection for cancer pain were given an infusion and then changed to oral ketamine with a 1:1 dose conversion. Pain and side effects were assessed throughout and 27 remained pain-controlled. The other two patients needed a dose increase to maintain pain control. The median oral ketamine dose was 300mg/day. In this group a 1:1 dose ratio for conversion from s.c. to oral ketamine was safe and effective.

Short Cuts prepared by Jason Boland, Consultant in Palliative Medicine, Barnsley Hospice, United Kingdom