Potent inhibition of burn pain without use of opiates

Pharmacokinetics and pharmacodynamics of lignocaine: A review

Lignocaine is an essential drug on World Health Organisation essential drug list, considered efficacious, safe and cost-effective for any health-care system. Despite its ubiquitous use in medicine and surgery, there are few detailed reviews of its pharmacokinetics and pharmacodynamics. Being an amide-type local anesthetic and Class 1b antiarrhythmic, lignocaine is most frequently used clinically for its anesthetic and antiarrhythmic benefits. However, lignocaine has important antinociceptive, immuno-modulating, and anti-inflammatory properties. Information pertaining to the pharmacokinetics and pharmacodynamics of lignocaine was examined by performing a literature search of PubMed, Embase and MEDLINE (via Ovid), pharmacology textbooks and online sources. We present a focused synopsis of lignocaine’s pharmacological composition, indications for use and mechanisms of action, focusing on its anti-inflammatory, immuno-modulating and analgesia effects. In addition we review the dosing regimes and infusion kinetics of lignocaine in the clinical setting. Finally, we review the evidence for ligocaine’s modulation of the inflammatory response during major surgery and its specific effects on cancer recurrence. These indirect effects of local anesthetics in tumor development may stem from the reduction of neuroendocrine responses to the stress response elicited by major surgery and tissue damage, enhanced preservation of immune-competence, in addition to opioid-sparing effects of modulating tumor growth.

Intravenous lidocaine for the treatment of background or procedural burn pain

BACKGROUND

This is an update of the review on "Lidocaine for pain relief in burn injured patients" first published in Issue 3, 2007, and first updated in 2012. Pain is a major issue for people with many different types of wounds, in particular those people with burn injuries. Prompt, aggressive use of opioid analgesics such as morphine has been suggested as critical to avert the cycle of pain and anxiety, but adverse effects are encountered. It has been proposed that newer agents such as lidocaine could be effective in reducing pain and alleviating the escalating opioid dosage requirements in people with burn injury.

OBJECTIVES

To assess the safety and effectiveness of intravenous lidocaine as a means of pain relief versus no therapy, placebo, other drugs, or a combination of these therapies in people with burn injury.

SEARCH METHODS

For this third update, we searched the Cochrane Central Register of Controlled Trials (Issue 11, 2013), and Ovid MEDLINE, MEDLINE in Process and Ovid EMBASE (up to December 2013).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and controlled clinical trials (CCTs), published and unpublished, which assessed the efficacy of intravenous lidocaine in varying doses as a single-agent therapy with no therapy, placebo, other analgesics (such as opioids), lidocaine plus another drug, or a combination of these therapies as a means of pain relief in people with burn injury.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data and assessed the risk of bias of the studies identified.

MAIN RESULTS

In this 2014 update, we found no new studies. The one small randomised double-blind placebo-controlled cross-over trial found in 2012, which included only 45 participants and compared intravenous lidocaine against placebo as a means of pain relief in people with burns still remains central to this review. We assessed this study as being at a high risk of bias due to its small size (fewer than 50 participants per treatment arm). Subjective pain ratings, as measured by the verbal rating scale, increased during procedures for both treatment arms; however, the increase was less in the lidocaine treatment group. There were no significant clinical or statistical differences regarding the effects of lidocaine and placebo on opioid requests and consumption, anxiety or level of satisfaction during a wound care procedure, but the small included study provided insufficient data to draw any conclusions.

AUTHORS' CONCLUSIONS

As current clinical evidence is based on only one RCT as well as case series and reports, intravenous lidocaine must be considered a pharmacological agent under investigation in burns care, the effectiveness of which is yet to be determined with further well-designed and conducted clinical trials.

Intravenous lidocaine for the treatment of background or procedural burn pain

BACKGROUND

This is an update of the review on 'Lidocaine for pain relief in burn injured patients' first published in Issue 3, 2007. Pain is a major issue for patients suffering from many different types of wounds, in particular those with burn injuries. Prompt, aggressive use of opioid analgesics such as morphine has been suggested as critical to avert the cycle of pain and anxiety, but side effects are encountered. It is proposed that newer agents such as lidocaine could be effective in reducing pain and alleviating the escalating opioid dosage requirements in patients with burn injury.

OBJECTIVES

To assess the safety and effectiveness of intravenous lidocaine as a means of pain relief versus no therapy, placebo, other drugs or two or more of the above therapies in combination in patients exposed to burn injury.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2011, Issue 2), MEDLINE (1966 to April 2011 week 4) and EMBASE (1980 to 2011 week 17).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and controlled clinical trials (CCTs), published and unpublished, which assessed the efficacy of intravenous lidocaine in varying doses as a single-agent therapy with no therapy, placebo, other analgesics such as opioids, lidocaine plus another drug, or two or more of the above therapies as a means of pain relief in patients exposed to burn injury.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data and assessed the risk of bias of the studies identified.

MAIN RESULTS

This update identified one new randomised, double-blind, placebo-controlled, cross-over trial which included 45 participants and compared intravenous lidocaine against placebo as a means of pain relief in those with burns. Subjective pain ratings as measured by the verbal rating scale increased during procedures for both treatment arms, however, the increase was less for the lidocaine treatment arm. There were no significant clinical or statistical differences regarding the effects of lidocaine and placebo on opioid requests and consumption, anxiety or level of satisfaction during a wound care procedure.

AUTHORS' CONCLUSIONS

As current clinical evidence is based on only one single RCT as well as case series and reports, intravenous lidocaine must be considered a pharmacological agent under investigation in burns care, the effectiveness of which is yet to be determined with further well-designed and conducted clinical trials.

Adjuvant use of intravenous lidocaine for procedural burn pain relief: a randomized double-blind, placebo-controlled, cross-over trial

BACKGROUND

Pain is a major issue for patients with severe burn. High dose intravenous opioids form the mainstay of procedural burns pain management; however it was suggested that intravenous lidocaine assists with minimising the pain experience. This study aimed to evaluate whether intravenous lidocaine improved analgesic efficacy and decreased opioid consumption during a burn wound care procedure.

METHODS

A prospective double-blind randomized crossover study compared intravenous lidocaine versus placebo alongside patient controlled analgesia (PCA) in 45 patients with severe burn undergoing wound care procedures (i.e. dressing change±debridement) on two consecutive days. Subjects were randomised to either the intervention or control condition on the first dressing day, and received the alternate condition on the second dressing day. During the intervention condition, subjects received lidocaine of 1.5 mg/kg/body weight followed by two boluses of 0.5 mg/kg at 5-min intervals followed by a continuous infusion. During the control condition, 0.9% sodium chloride was administered at an equivalent volume, dose and rate to that of lidocaine. Primary end points included pain intensity as measured by verbal rating scale (VRS), time to rescue analgesia, opioid requests and consumption and overall anxiety and level of satisfaction.

RESULTS

Changes in the VRS score was significantly lower for lidocaine [difference (95% CI)=0.36 (0.17-0.55)] as compared to placebo. However, there were no significant clinical or statistical differences regarding the effects of lidocaine and placebo on opioid requests and consumption, anxiety or level of satisfaction during the first and second dressing procedures.

CONCLUSIONS

In this study, the clinical benefit of intravenous lidocaine for pain relief during burn wound dressing changes in terms of overall pain scores and opioid consumption was unremarkable. Further investigations using different lidocaine regimes for the management of procedural burn pain are warranted.

Lidocaine for pain relief in burn injured patients

BACKGROUND

Pain is a major issue for patients suffering from many different types of wounds in particular those with burn injuries. Prompt, aggressive use of opioid analgesics such as morphine has been suggested as critical to avert the cycle of pain and anxiety, but side effects are encountered. It is proposed that newer agents such as lidocaine could be effective in reducing pain and alleviating the escalating opioid dosage requirements in patients with burn injury.

OBJECTIVES

To assess the safety and effectiveness of intravenous lidocaine as a means of pain relief versus no therapy, placebo, other drugs or two or more of the above therapies in combination in patients exposed to burn injury.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2007), MEDLINE (1966 to March 2007), EMBASE (1980 to 2007), CINAHL (1982 to March 2007).

SELECTION CRITERIA

Those trials that were considered were: randomised controlled trials (RCTs) and controlled clinical trials (CCTs), both published and unpublished studies, which assessed the efficacy of intravenous lidocaine varying doses as a single-agent therapy with no therapy, placebo, other analgesics such as opioids, lidocaine plus another drug, or two or more of the above therapies as a means of pain relief in patients exposed to burn injury.

DATA COLLECTION AND ANALYSIS

The two review authors applied the entry criteria to identified studies.

MAIN RESULTS

No clinically relevant RCTs or CCTs were identified through the above searches.

AUTHORS' CONCLUSIONS

No information is available from the published RCTs or CCTs on clinically relevant primary outcome measures which can influence current burns care practice and management. Therefore, since current clinical evidence is subject to the inherent weaknesses of case series or reports, intravenous lidocaine must be considered a pharmacological agent under investigation in burns care whose effectiveness is yet to be determined in well-designed and conducted clinical trials.

Anti-inflammatory properties of local anesthetics and their present and potential clinical implications

Development of new local anesthetic agents has been focused on the potency of their nerve-blocking effects, duration of action and safety and has resulted in a substantial number of agents in clinical use. It is well established and well documented that the nerve blocking effects of local anesthetics are secondary to their interaction with the Na+ channels thereby blocking nerve membrane excitability and the generation of action potentials. Accumulating data suggest however that local anesthetics also possess a wide range of anti-inflammatory actions through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes. The potent anti-inflammatory properties of local anesthetics, superior in several aspects to traditional anti-inflammatory agents of the NSAID and steroid groups and with fewer side-effects, has prompted clinicians to introduce them in the treatment of various inflammation-related conditions and diseases. They have proved successful in the treatment of burn injuries, interstitial cystitis, ulcerative proctitis, arthritis and herpes simplex infections. The detailed mechanisms of action are not fully understood but seem to involve a reversible interaction with membrane proteins and lipids thus regulating cell metabolic activity, migration, exocytosis and phagocytosis.