Intraspinal drug infusion using fully implantable pump and catheter systems is a safe and effective therapy for selected patients with chronic pain. The options for this approach are increasing, as drugs that are commercially available for systemic administration are adapted to this use and other drugs that are in development specifically for intraspinal administration become available. In 2000 a Polyanalgesic Consensus Conference was organized to evaluate the existing literature and develop guidelines for drug selection. The major outcome of this effort, an algorithm for drug selection, was based on the best available evidence at the time. Rapid changes have occurred in the science and practice of intraspinal infusion and a Polyanalgesic Consensus Conference 2003 was organized to pursue the following goals: 1) to review the literature on intraspinal drug infusion since 1999, 2) to revise the 2000 drug-selection algorithm, 3) to develop guidelines for optimizing drug dosage and concentration, 4) to create a process for documenting minimum evidence supporting the use of a drug for intraspinal infusion, and 5) to clarify issues pertaining to compounding of drugs. Based on the best available evidence and expert opinion, consensus recommendations were developed in all these areas. The panel's conclusions may provide a foundation for clinical practice and a rational basis for new research.

Although certain risk factors can identify individuals who are most likely to develop chronic pain, few interventions to prevent chronic pain have been identified. To facilitate the identification of preventive interventions, an IMMPACT meeting was convened to discuss research design considerations for clinical trials investigating the prevention of chronic pain. We present general design considerations for prevention trials in populations that are at relatively high risk for developing chronic pain. Specific design considerations included subject identification, timing and duration of treatment, outcomes, timing of assessment, and adjusting for risk factors in the analyses. We provide a detailed examination of 4 models of chronic pain prevention (i.e., chronic post-surgical pain, postherpetic neuralgia, chronic low back pain, and painful chemotherapy-induced peripheral neuropathy). The issues discussed can, in many instances, be extrapolated to other chronic pain conditions. These examples were selected because they are representative models of primary and secondary prevention, reflect persistent pain resulting from multiple insults (i.e., surgery, viral infection, injury, and toxic/noxious element exposure), and are chronically painful conditions that are treated with a range of interventions. Improvements in the design of chronic pain prevention trials could improve assay sensitivity and thus accelerate the identification of efficacious interventions. Such interventions would have the potential to reduce the prevalence of chronic pain in the population. Additionally, standardization of outcomes in prevention clinical trials will facilitate meta-analyses and systematic reviews and improve detection of preventive strategies emerging from clinical trials.

SummaryThe regulators of G protein signaling (RGS) are a family of cellular proteins that play an essential regulatory role in G protein-mediated signal transduction. There are multiple RGS subfamilies consisting of over twenty different RGS proteins. They are basically the guanosine triphosphatase (GTPase)-accelerating proteins that specifically interact with G protein α subunits. RGS proteins display remarkable selectivity and specificity in their regulation of receptors, ion channels, and other G protein-mediated physiological events. The molecular and cellular mechanisms underlying such selectivity are complex and cooperate at many different levels. Recent research data have provided strong evidence that the spatiotemporal-specific expression of RGS proteins and their target components, as well as the specific protein-protein recognition and interaction through their characteristic structural domains and functional motifs, are determinants for RGS selectivity and specificity. Other molecular mechanisms, such as alternative splicing and scaffold proteins, also significantly contribute to RGS selectivity. To pursue a thorough understanding of the mechanisms of RGS selective regulation will be of great significance for the advancement of our knowledge of molecular and cellular signal transduction.

BackgroundProblems with intravenous patient-controlled analgesia (IV PCA) are well known, including invasive route of delivery and pump programming errors. The primary objective of this study was to evaluate patient satisfaction with a novel sublingual sufentanil PCA system (sufentanil sublingual tablet system 15 mcg with a 20-minute lockout interval; SSTS) to IV PCA morphine sulfate 1 mg with a 6-minute lockout interval (IV PCA MS) for the management of acute postoperative pain.MethodsThis was a randomized, open-label, 48-hour non-inferiority study with optional extension to 72 hours at 26 U.S. sites enrolling patients scheduled for elective major open abdominal or orthopedic (hip or knee replacement) surgery. The primary outcome measure was the proportion of patients who responded “good” or “excellent” (collectively “success”) at the 48-hour timepoint on the Patient Global Assessment of method of pain control (PGA48).ResultsA total of 357 patients received study drug and 78.5% vs. 65.6% of patients achieved PGA48 “success” for SSTS vs. IV PCA MS, respectively, demonstrating non-inferiority (P < 0.001 using the one-side Z-test against the non-inferiority margin) as well as statistical superiority for treatment effect (P = 0.007). Patients using SSTS reported more rapid onset of analgesia and patient and nurse ease of care and satisfaction scores were higher than IV PCA MS. Adverse events were similar between the 2 groups; however, SSTS had fewer patients experiencing oxygen desaturations below 95% compared to IV PCA MS (P = 0.028).ConclusionsSufentanil sublingual tablet system is a promising new analgesic technology that may address some of the concerns with IV PCA.

Rapid opioid dose escalation, possibly caused by tolerance, has been observed in some patients on daily opioid therapy, although clinically identifiable characteristics of these patients are unknown. In this retrospective chart review of 206 patients, we examined whether the age of the patient was related to opioid escalation. Initial starting doses of long-acting opioids were similar in younger patients (< or =50 yr; 49 +/- 3 mg/d oral morphine-equivalent dose) versus older patients (> or =60 yr; 42 +/- 3 mg/d). Younger patients reached a maximum dose of 452 +/- 63 mg/d over 15.0 +/- 1.3 mo, whereas older patients achieved a maximum dose of 211 +/- 23 mg/d over 14.4 +/- 1.5 mo (P < 0.0001). At the last clinic visit, younger-patient dosing averaged 365 +/- 61 mg/d, with older patients averaging 168 +/- 18 mg/d (P < 0.0001). Only older patients demonstrated a reduction in visual analog scale scores from start of opioid therapy until discharge from the clinic (6.9 +/- 0.3 to 5.6 +/- 0.3; P < 0.01). These clinical data suggest that age is an important variable in opioid dose escalation. Although factors other than opioid tolerance can result in dose escalation, it is possible that older patients may have a reduced rate of tolerance development.