Liposomal lidocaine to improve procedural success rates and reduce procedural pain among children: a randomized controlled trial

BackgroundHistorically, children have been undertreated for their pain, and they continue to undergo painful cutaneous procedures without analgesics. A new topical anesthetic, liposomal lidocaine 4% cream (Maxilene, RGR Pharma, Windsor, Ont.), has become available. It has pharmacologic properties that are superior to other topical anesthetics, including an onset of action of only 30 minutes. We sought to determine the success rate of cannulation, analgesic effectiveness, procedure duration and rate of adverse skin reactions when liposomal lidocaine is used before intravenous cannulation of children.MethodsIn this double-blind randomized controlled trial, children aged 1 month to 17 years received liposomal lidocaine or placebo before cannulation. Success on first cannulation attempt was recorded, and, among children 5 years and older, pain was evaluated before and after the attempt by the child, parents and research assistant using a validated measure (Faces Pain Scale-Revised). For children younger than 5 years, pain was evaluated by the parents and research assistant only. The total duration of the procedure and adverse skin reactions were also recorded.ResultsBaseline characteristics did not differ (p > 0.05) between children who received liposomal lidocaine (n = 69) and those who received placebo (n = 73). Cannulation on the first attempt was achieved in 74% of children who received liposomal lidocaine compared with 55% of those who received placebo (p = 0.03). Among children 5 years of age and older (n = 67), lower mean pain scores during cannulation were reported by those receiving liposomal lidocaine (p = 0.01). Similarly, lower mean pain scores during cannulation were reported by the parents and research assistant for all children who received liposomal lidocaine than for all those who received placebo (p < 0.001). The mean total procedure duration was shorter with liposomal lidocaine (6.7 v. 8.5 minutes; p = 0.04). The incidence of transient dermal changes was 23% in both groups (p = 1.0).ConclusionsUse of liposomal lidocaine was associated with a higher intravenous cannulation success rate, less pain, shorter total procedure time and minor dermal changes among children undergoing cannulation. Its routine use for painful cutaneous procedures should be considered whenever feasible.Painful medical procedures are routinely performed on children for diagnostic and therapeutic reasons. The provision of analgesia for these procedures, however, remains uncommon.¹ Untreated pain has both short-term and long-term consequences. In the short term, there is pain during the actual procedure. This contributes to a lack of cooperation by the child, unsuccessful procedure attempts, repeated attempts, additional pain and a prolonged total procedure time. In the long term, repeated painful procedures can lead to conditioned anxiety responses and increased pain perception.^2,3 Inadequate analgesia during an initial procedure may diminish analgesic effectiveness at subsequent procedures.⁴ Moreover, there is a relation between painful procedures in childhood and blood-injection-injury phobia,⁵ a condition that affects up to 10% of adults and may cause people to avoid medical care.⁶ In light of the cumulative evidence of the negative consequences of untreated pain in childhood, interventions are needed to diminish pain among children undergoing medical procedures and to facilitate successful completion of procedures.Intravenous cannulation is a common, painful medical procedure. Although local anesthetics reduce the pain of cannulation,^7,8,9,10,11 most preparations are not feasible for routine use. The “gold standard” for skin anesthesia, lidocaine–prilocaine 5% cream, requires a 60-minute application time. In addition, it causes vasoconstriction,¹² which potentially obscures landmarks and makes cannulation more difficult.¹³ Another commercially available preparation, amethocaine 4% gel, requires a 30-minute application time. However, it frequently causes vasodilatation and may induce hypersensitivity with repeated use.¹⁴ An alternative option, subcutaneous injection of lidocaine, requires only a few minutes to administer, but it is associated with an extra and painful puncture and is therefore not routinely used.¹⁵Liposomal lidocaine 4% cream¹⁶ (Maxilene, RGR Pharma, Windsor, Ont.) was launched in Canada in 2003. The liposome-encapsulated formulation protects the anesthetic from being metabolized too quickly.¹⁷ Liposomal lidocaine has the advantages of “needle-free” administration, a short onset of action and minimal vasoactive properties that minimize any potential interference with cannulation success. It is not associated with methemoglobinemia, a systemic side effect of lidocaine–prilocaine.¹⁸Among children, liposomal lidocaine is as effective as lidocaine–prilocaine for decreasing pain from venipuncture¹⁹ and intravenous cannulation,^20,21 and as effective as buffered lidocaine injection for decreasing intravenous cannulation pain.¹⁵ Previous studies have not compared liposomal lidocaine with placebo. We conducted such a comparison to determine whether liposomal lidocaine improves cannulation success rates. We also sought to determine whether it reduces pain and procedure duration and is associated with a low frequency of dermal reactions.     

IL-1 regulates cytoskeletal organization in osteoclasts via TNF receptor-associated factor 6/c-Src complex

Targeted disruption of either c-Src or TNFR-associated factor 6 (TRAF6) in mice causes osteoclast dysfunction and an osteopetrotic phenotype, suggesting that both molecules play important roles in osteoclastic bone resorption. We previously demonstrated that IL-1 induces actin ring formation and osteoclast activation. In this study, we examined the relationship between IL-1/TRAF6-dependent and c-Src-mediated pathways in the activation of osteoclast-like cells (prefusion cells (pOCs); multinucleated cells) formed in the murine coculture system. In normal pOCs, IL-1 induces actin ring formation and tyrosine phosphorylation of p130(Cas), a known substrate of c-Src. However, in Src-deficient pOCs, p130(Cas) was not tyrosine phosphorylated following IL-1 treatment. In normal pOCs treated with IL-1, anti-TRAF6 Abs coprecipitate p130(Cas), protein tyrosine kinase 2, and c-Src. In Src-deficient pOCs, this molecular complex was not detected, suggesting that c-Src is required for formation of the TRAF6, p130(Cas), and protein tyrosine kinase 2 complex. Moreover, an immunocytochemical analysis revealed that in osteoclast-like multinucleated cells, IL-1 induced redistribution of TRAF6 to actin ring structures formed at the cell periphery, where TRAF6 also colocalized with c-Src. Taken together, these data suggest that IL-1 signals feed into the tyrosine kinase pathways through a TRAF6-Src molecular complex, which regulates the cytoskeletal reorganization essential for osteoclast activation.     

The human interferon receptor: NMR-based modeling, mapping of the IFN-alpha 2 binding site, and observed ligand-induced tightening

The human interferon receptor (IFNAR) mediates the antiviral and antiproliferative activities of type I interferons (IFNs). This receptor is comprised of subunits IFNAR1 and IFNAR2, the latter exhibiting nanomolar affinity for IFNs. Here the extracellular domain of IFNAR2 (IFNAR2-EC), a soluble 25 kDa IFN-binding polypeptide, and its complex with IFN-alpha 2 were studied using multidimensional NMR. IFNAR2-EC is comprised of two fibronectin-III (FN-III) domains connected by a helical hinge region. The deduced global fold was utilized to improve the alignment of IFNAR2-EC against structurally related receptors and to model its structure. A striking feature of IFNAR2-EC is the limited and localized deviations in chemical shifts exhibited upon ligand binding, observed for only 15% of its backbone (1)H and (15)N nuclei. Analysis of these deviations maps the IFN-alpha 2 binding site upon IFNAR2-EC to a contiguous surface on the N-terminal domain, including the S3-S4 loop (residues 44-53), the S5-S6 loop and S6 beta-strand (residues 74-82), and the S7 beta-strand and the hinge region (residues 95-105). The C-terminal domain contributes only marginally to ligand binding, and no change in the hypothesized interdomain interface is observed. The proposed binding domain encompasses all residues implicated by mutagenesis studies in IFN binding, and suggests adjacent residues cooperate in forming the binding surface. D(2)O-exchange experiments indicate that binding of IFN-alpha2 induces tightening of the N-terminal domain of IFNAR2-EC. This increase in receptor rigidity may play an important role in initiating the intracellular stage of the IFN signaling cascade.     

Ethical framework for observational studies of medicinal drug exposure in pregnancy

BACKGROUND: The conduct of human research in the teratogenicity of drugs, chemicals, radiation and infections is needed in order to close critical gaps in knowledge. METHODS: We reviewed the various aspects of the ethics of conducting prospective human research in teratogenicity. RESULTS: Such research should respect the confidentiality of pregnant women and their families. Because this research is observational, interpretation of results is difficult, and the study design should strive to meet the highest possible scientific standards attainable in the particular research conditions. It should also be acknowledged that confidentiality cannot be always adhered to (e.g., if the interview reveals risks to minors). CONCLUSIONS: In general, the benefit risk ratio in this type of research is very favorable, although in specific cases the research follow-up may induce fears (e.g., drugs of abuse) in the woman being interviewed.     

Multiple mechanisms for the activation of human platelet aggregation by Staphylococcus aureus: roles for the clumping factors ClfA and ClfB,the serine-aspartate repeat protein SdrE and protein A

The ability of Staphylococcus aureus cells to induce platelet aggregation has long been recognized. However, despite several attempts to identify the mechanisms involved in this interaction, the nature of the bacterial receptors required remains poorly understood. Using genetic manipulation, this study for the first time provides clear evidence that several S. aureus surface proteins participate in the inter-action with platelets. Mutants of S. aureus strain Newman lacking one or more surface proteins were tested for their ability to stimulate platelet aggregation. This approach was complemented by the expression of a number of candidate proteins in the non-aggregating Gram-positive bacterium Lacto-coccus lactis. S. aureus-induced aggregation was monophasic and was dependent on the platelet receptor GPIIb/IIIa. The fibrinogen-binding proteins, clumping factors A and B and the serine-aspartate repeat protein SdrE could each induce aggregation when expressed in L. lactis. Although protein A expressed in L. lactis was not capable of inducing aggregation independently, it enhanced the aggregation response when expressed on the surface of S. aureus. Thus, S. aureus has multiple mechanisms for stimulating platelet aggregation. Such functional redundancy suggests that this phenomenon may be important in the pathogenesis of invasive diseases such as infective endocarditis.