Temporal effects of topical morphine application on cutaneous wound healing

Analgesic Efficacy of Oxycodone in Postoperative Dressings after Surgical Treatment of Burn Wounds: A Randomised Controlled Trial

INTRODUCTION

This study aimed to assess the analgesic efficacy of oxycodone at doses of 10 mg and 20 mg in dressings after surgery of burn wounds.

MATERIAL AND METHODS

Twenty adult patients who underwent surgical treatment of third-degree burn wounds under general anaesthesia were included. Burn wounds were treated with dressings, to which oxycodone was added at 20 mg in Group 1 and 10 mg in Group 2. After the surgery, plasma oxycodone and noroxycodone concentrations were assayed, and pain intensity was assessed with Numerical Rating Scale (NRS).

RESULTS

In Group 1, no patient reported pain; in Group 2, four patients reported pain. The pain intensity, according to NRS, was 1-8. Plasma concentration of oxycodone in the blood serum was in the range of 1.24-3.15 ng/mL and 1.09-1.28 ng/mL in Group 1 and Group 2, respectively. Noroxycodone was not detected in the plasma. Adverse effects were not observed in any of the treated patients.

CONCLUSIONS

Oxycodone in dressings provides patients with adequate and safe analgesia.

Chronic wound-related pain, wound healing and the therapeutic potential of cannabinoids and endocannabinoid system modulation

Chronic wounds represent a significant burden on the individual, and the healthcare system. Individuals with chronic wounds report pain to be the most challenging aspect of living with a chronic wound, with current therapeutic options deemed insufficient. The cutaneous endocannabinoid system is an important regulator of skin homeostasis, with evidence of system dysregulation in several cutaneous disorders. Herein, we describe the cutaneous endocannabinoid system, chronic wound-related pain, and comorbidities, and review preclinical and clinical evidence investigating endocannabinoid system modulation for wound-related pain and wound healing. Based on the current literature, there is some evidence to suggest efficacy of endocannabinoid system modulation for promotion of wound healing, attenuation of cutaneous disorder-related inflammation, and for the management of chronic wound-related pain. However, there is 1) a paucity of preclinical studies using validated models, specific for the study of chronic wound-related pain and 2) a lack of randomised control trials and strong clinical evidence relating to endocannabinoid system modulation for wound-related pain. In conclusion, while there is some limited evidence of benefit of endocannabinoid system modulation in wound healing and wound-related pain management, further research is required to better realise the potential of targeting the endocannabinoid system for these therapeutic applications.

Accelerated wound healing and its promoting effects of topical codeine on the healing of full-thickness cutaneous wound, evidences for modulating cytokines involved in pain, inflammation and collagen biosynthesis

INTRODUCTION

The inflammation and pain occur in all the wounds. Opioids drugs decrease pain and may act as an anti-inflammation. The current study was conducted to investigate the efficiency of the topical uses of Codeine on full-thickness excision wound models by focusing on relationship between pain mediators, inflammation and wound healing rate.

METHODS

Following the induction of anesthesia, a skin wound with a size of 7-mm punch was induced on the dorsal surfaces of each mouse. The mice were divided into five categories: groups I-III were daily administered 2.5%, 5%, and 10% Codeine gel; those in group IV were administered phenytoin cream, and group V (controls) received base ointment. To assess the effects of Codeine gel on the wound healing process, the wound area, histological parameters, and the relative protein expression of CXCR1, CXCR2, IL-6, IL-6R, PDGF, PDGFR, and COL1A along with the plasma concentrations of IL-1β, IL-10, and TNF-α were investigated on days 3, 7, and 14.

RESULTS

On days 7 and 14, the wound area was significantly lower in the treated mice compared to the controls (P < 0.05). Angiogenesis, collagen deposition, and epithelium thickness were significantly higher in the treatment groups compared to the control group (P < 0.05). The relative protein expressions of CXCR1, CXCR2, IL-6, and IL-6R and the plasma concentrations of IL-1β and TNF-α were significantly lower in the treated groups. Meanwhile, the relative protein expressions of PDGF, PDGFR, and COL1A and the plasma concentration of IL-10 were significantly higher in the treated mice (P < 0.05).

CONCLUSION

Administration of Codeine gel accelerated wound healing through decreasing the pain mediators, inflammation and promoting proliferative phase.

Opioids and Ocular Surface Pathology; A Literature Review of New Treatments Horizons

This review discusses the role of opioids in the corneal surface and the different pathways and therapeutic methods of management. A literature review was performed using PubMed database. For the database search, the main searching words “opioid” and “topical opioid treatment” were used with the descriptors “cornea”, “ocular surface”, “neuropathic corneal pain”, “corneal sensitivity” and “naltrexone”; original scientific articles and reviews were included to achieve the purpose of the review. The endogenous opioid system has relevant functions in the organism, and in daily use, opioids are used as painkillers. However, these drugs may be employed for other indications as opioid pathways have a wide spectrum. The corneal surface for topical treatment is easily accessible, hence sparing the side effects of systemic opioids. Instillation of opioid antagonist substances, such as naltrexone, increases corneal healing rates and stimulates the division of corneal epithelium cells without deleterious effects. The natural modulation of endogenous opioids controls different forms of pain, including inflammatory and neuropathic pain, both in the ocular surface and in the central nervous system. There are diverse methods in controlling pain using opioids, especially in refractory forms. This review attempts to collect the literature about corneal surface and opioid pathways to provide an overview image and a possible direction of the news treatments.

Biphalin-A Potent Opioid Agonist-As a Panacea for Opioid System-Dependent Pathophysiological Diseases?

Biphalin, one of the opioid agonists, is a dimeric analog of enkephalin with a high affinity for opioid receptors. Opioid receptors are widespread in the central nervous system and in peripheral neuronal and non-neuronal tissues. Hence, these receptors and their agonists, which play an important role in pain blocking, may also be involved in the regulation of other physiological functions. Biphalin was designed and synthesized in 1982 by Lipkowski as an analgesic peptide. Extensive further research in various laboratories on the antinociceptive effects of biphalin has shown its excellent properties. It has been demonstrated that biphalin exhibits an analgesic effect in acute, neuropathic, and chronic animal pain models, and is 1000 times more potent than morphine when administered intrathecally. In the course of the broad conducted research devoted primarily to the antinociceptive effect of this compound, it has been found that biphalin may also potentially participate in the regulation of other opioid system-dependent functions. Nearly 40 years of research on the properties of biphalin have shown that it may play a beneficial role as an antiviral, antiproliferative, anti-inflammatory, and neuroprotective agent, and may also affect many physiological functions. This integral review analyzes the literature on the multidirectional biological effects of biphalin and its potential in the treatment of many opioid system-dependent pathophysiological diseases.

Assessment of the structural and functional characteristics of human mesenchymal stem cells associated with a prolonged exposure of morphine

The discovery of the expression of opioid receptors in the skin and their role in orchestrating the process of tissue repair gave rise to questions regarding the potential effects of clinical morphine treatment in wound healing. Although short term treatment was reported to improve tissue regeneration, in vivo chronic administration was associated to an impairment of the physiological healing process and systemic fibrosis. Human mesenchymal stem cells (hMSCs) play a fundamental role in tissue regeneration. In this regard, acute morphine exposition was recently reported to impact negatively on the functional characteristics of hMSCs, but little is currently known about its long-term effects. To determine how a prolonged treatment could impair their functional characteristics, we exposed hMSCs to increasing morphine concentrations respectively for nine and eighteen days, evaluating in particular the fibrogenic potential exerted by the long-term exposition. Our results showed a time dependent cell viability decline, and conditions compatible with a cellular senescent state. Ultrastructural and protein expression analysis were indicative of increased autophagy, suggesting a relation to a detoxification activity. In addition, the enhanced transcription observed for the genes involved in the synthesis and regulation of type I collagen suggested the possibility that a prolonged morphine treatment might exert its fibrotic potential risk, even involving the hMSCs.

Opium poisoning following self-medication of radiation-induced dermatitis with topical use of opium latex traditional extract; a teaching case

Despite Radiation-induced dermatitis is a self-limiting complication, it can be complicated if inappropriate self-medications have been used such as opium latex traditional extract.

Negative pharmacological effect on spine fusion: A narrative review of the literature of evidence-based treatment

Spine fusion surgery is commonly performed for diverse indications, the most frequent one being degenerative spine diseases. Despite the growing importance of this surgery, there is limited evidence concerning the effects of drugs on the process of spine fusion and healing. While asymptomatic sometimes, nonunion of the spine can have tremendous repercussions on the patients' quality of life and the healthcare system rendering it an "expensive complication". This literature review identifies the role of some perioperative drugs in spine fusion and reveals their potential role in pseudarthrosis of the spine. This review also benefits spine surgeons looking for current evidence-based practices. We reviewed the data related to nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, vancomycin, bisphosphonates, proton pump inhibitors (PPIs), pregabalin, and opioids. From the available experimental and clinical studies, we conclude that bisphosphonates might positively influence the process of spine fusion, while steroids and vancomycin have shown variable effects, and the remaining medications likely disturb healing and union of the spine. We recommend spine surgeons be cautious about the drugs they resort to in the critical perioperative period until further clinical studies prove which drugs are safe to be used.

Macrophages in dermatology: pathogenic roles and targeted therapeutics

The field of macrophage biology is rapidly growing. Recent studies have shifted focus from classic wound healing roles to newly identified roles in dermatologic pathology. These studies have identified pathogenic roles of macrophages in relatively common conditions, such as psoriasis, skin cancer, and cutaneous T-cell lymphoma. Selective depletion of these cells or their associated cytokines leads to improved clinical outcome. Herein, we review recent animal and human studies that have elucidated novel pathogenic roles of macrophages in conditions frequently encountered by dermatologists and discuss clinically relevant macrophage-targeted therapies.

Immediate fat and nanofat-enriched fat grafting in breast reduction for scar management

BACKGROUND

Reduction mammoplasty can be successful but surgical scars may continue to be a most undesirable and unavoidable outcome. Various medical and non-invasive methods are available to minimize scar formation but as yet no methods have been discovered to eliminate them. We hypothesize that immediate fat and nanofat-enriched fat graft transfer may improve the scar quality and optimize results.

MATERIALS AND METHODS

This prospective study comprised 45 superomedial pedicle wise-pattern breast reduction patients divided into three groups of 15 in a randomized fashion. The control group had no additional injections whereas the other two groups received injections of fat and nanofat-enriched fat grafts immediately under their surgery scars, respectively. Surgical scar formation was evaluated at six months and scars were scored using the Vancouver scar scale and a visual analogue scale.

RESULTS

Fat and nanofat-enriched fat graft-injected groups scored significantly better on all items of the Vancouver scar scale, except for scar height, compared to the control group (p < 0.05). Visual analogue scores were significantly lower in the fat and nanofat-enriched fat graft-injected groups compared to the control group (p < 0.05).

CONCLUSIONS

In breast reduction patients, simultaneous fat and nanofat-enriched fat grafting appears to be a safe and promising strategy for scar management.

Analgesic efficacy of sufentanil in dressings after surgical treatment of burn wounds

BACKGROUND

The aim of this study was to assess the analgesic efficacy of sufentanil in dressings after surgical treatment of burn wounds.

PATIENTS AND METHODS

Twenty adult patients, who underwent surgical treatment of third-degree burn wounds under general anesthesia, were included. Two of the patients underwent surgery twice. During surgery, patients received 50-100 μg fentanyl every 20-30 min and, after surgery, patients received 100 mg ketoprofen twice daily. Additionally, ten patients (group 1) received 50 μg sufentanil added to the burn wound dressings soaked in octenidine and phenoxyethanol while 10 patients (group 2) received 25 μg sufentanil added to the same dressings. The rescue analgesic, which was administered when pain intensified, was 5 mg subcutaneous morphine. Plasma sufentanil concentrations were assayed at 1, 2, 3, and 6 h after surgery completion and when pain was reported, along with pain intensity evaluation.

RESULTS

Sufentanil was not detected in the serum of any patients. Rescue morphine was given during the postoperative period (24 h) in one patient in group 1 (who underwent surgery twice) and three patients in group 2. The mean sufentanil concentration in dressings was higher in group 1 (0.13 ± 0.03) than group 2 (0.06 ± 0.03 μg/mL; p < 0.001). The group 1 patient who received rescue morphine had a sufentanil concentration of 0.10 μg/mL, which was the lowest concentration in group 1. Group 2 patients who received rescue morphine had sufentanil concentrations of at least two-fold lower (0.03-0.05 μg/mL). No adverse effects were observed.

CONCLUSIONS

Sufentanil in dressings after burn wound surgery provides effective and safe analgesia and the sufentanil concentration in dressings should be ≥0.10 μg/mL in a solution of octenidine and phenoxyethanol.

The analgesic hybrid of dermorphin/substance P and analog of enkephalin improve wound healing in streptozotocin-induced diabetic rats

The purpose of this study was to investigate the effect of the peptide analgesic hybrid compounds: AWL3106 analog of dermorphin and substance P (7-11), and biphalin enkephalin analog on wound healing in streptozotocin-induced diabetic rats. The diabetes was induced in 6-7 week-old male Wistar rats by intraperitoneal injection of streptozotocin. After 70 days, the wounds were created on the back of the rats and then, once a day for 21 days, the dressing containing lanolin ointment, 10% of keratin scaffolds, and 1 mM of AWL3106 or biphalin was applied. The wounds histology were analyzed by hematoxylin and eosin staining. The orientation and organization of collagen was analyzed by Masson's trichome staining. The number of macrophages, blood vessels, and fibroblasts were visualized by CD68, CD34, and vimentin immunoreactivity, respectively. Our results demonstrated that the wound area of AWL3106- and biphalin-treated groups was greatly reduced (up to 47% on the 7 day) in comparison with untreated diabetic groups. The immunohistochemical staining of macrophages demonstrated that AWL3106 and biphalin accelerated inflammatory progression and subsequently decreased persistent inflammation. The histological analysis showed that the structure of tissue in the groups under the study was very similar to the one of wound tissue in N-DM group. The H&E and Masson's trichome staining demonstrated that the orientation and organization of collagen as well as the number and shape of blood vessels were better in 3106- and BIF-treated group than in DM group. In conclusion, the obtained data suggested that our hybrid peptides enhanced wound healing, particularly by accelerating the inflammatory phase and promoted the wound closure.

Perioperative outcomes among chronic opioid users who receive lobectomy for non-small cell lung cancer

OBJECTIVE

We sought to identify whether chronic opioid users are at increased risk for complications or hospital readmission following lobectomy for non-small cell lung cancer.

METHODS

The National Cancer Institute Surveillance, Epidemiology, and End Results-Medicare database was queried to identify patients older than age 65 years who received a lobectomy for non-small cell lung cancer. Chronic opioid users were identified through Medicare Part D records and were defined as those with >120 cumulative days of opioid supply for the year before surgery. A systematic 1:2 propensity matching was performed among chronic opioid users.

RESULTS

Six thousand four hundred thirty-seven patients were identified, among whom 3627 (56%) were opioid naïve, 1866 (29%) were intermittent opioid users, and 944 (15%) were chronic opioid users. After propensity matching, 30-day mortality and 90-day mortality were nearly 2-fold higher among chronic opioid users compared with nonchronic users. In addition, length of stay and hospital charges were increased among chronic opioid users (median, 6 vs 7 days and mean increase, $12,526, respectively). Multivariable analysis revealed that intermittent opioid users and chronic opioid users were associated with an increased risk of 90-day hospital readmission compared with opioid-naïve patients (odds ratio, 1.35; 95% confidence interval, 1.07-1.71 and odds ratio, 1.72; 95% confidence interval, 1.40-2.12, respectively), predominantly burdened by infectious, renal, and pulmonary causes.

CONCLUSIONS

Patients who chronically use opioids before lobectomy represent high-risk patients. The risk of 30- and 90-day mortality, length of stay, hospital charges, and 90-day readmission after lobectomy among chronic opioid users are substantially elevated.

Preoperative Chronic Opioid Therapy: A Risk Factor for Complications, Readmission, Continued Opioid Use and Increased Costs After One- and Two-Level Posterior Lumbar Fusion

STUDY DESIGN

Retrospective, economic analysis.

OBJECTIVE

To study patient profile associated with preoperative chronic opioid therapy (COT), and study COT as a risk factor for 90-day complications, emergency department (ED) visits, and readmission after primary one- to two-level posterior lumbar fusion (PLF) for degenerative spine disease. We also evaluated associated costs, risk factors, and adverse events related to long-term postoperative opioid use.

SUMMARY OF BACKGROUND DATA

Chronic opioid use is associated with poor outcomes and dependence after spine surgery. Risk factors, complications, readmissions, adverse events, and costs associated with COT in patients undergoing lumbar fusion are not entirely known. As providers look to reduce healthcare costs and improve outcomes, identification of modifiable risk factors is important.

METHODS

Commercial insurance data from 2007 to Q3-2015 was used to study preoperative opioid use in patients undergoing primary one- to two-level PLF. Ninety-day complications, ED visits, readmissions, 1-year adverse events, and associated costs have been described. Multiple-variable regression analyses were done to study preoperative COT patient profile and opioid use as a risk factor for complications and adverse events.

RESULTS

A total of 24,610 patients with a mean age of 65.6 ± 11.5 years were included. Five thousand five hundred (22.3%) patients had documented opioid use for more than 6 months before surgery, and 87.4% of these had continued long-term use postoperatively. On adjusted analysis, preoperative COT was found to be a risk factor for 90-day wound complications, pain diagnoses, ED visits, readmission, and continued use postoperatively. Postspinal fusion long-term opioid users had an increased utilization of epidural/facet joint injections, risk for revision fusion, and increased incidence of new onset constipation within 1 year postsurgery. The cost associated with increase resource use in these patients has been reported.

CONCLUSION

Preoperative COT is a modifiable risk factor for complications, readmission, adverse events, and increased costs after one- or two-level PLF.

LEVEL OF EVIDENCE

3.

Opioids prevent regeneration in adult mammals through inhibition of ROS production

Inhibition of regeneration and induction of tissue fibrosis are classic outcomes of tissue repair in adult mammals. Here, using a newly developed model of regeneration in adult mammals i.e. regeneration after massive resection of an inguinal fat pad, we demonstrate that both endogenous and exogenous opioids prevent tissue regeneration in adults, by inhibiting the early production of reactive oxygen species (ROS) that generally occurs after lesion and is required for regeneration. These effects can be overcome and regeneration induced by the use of an opioid antagonist. The results obtained in both our new model and the gold standard adult zebrafish demonstrate that this mechanism can be considered as a general paradigm in vertebrates. This work clearly demonstrates that ROS is required for tissue regeneration in adult mammals and shows the deleterious effect of opioids on tissue regeneration through the control of this ROS production. It thus raises questions about opioid-based analgesia in perioperative care.

Local Resiniferatoxin Induces Long-Lasting Analgesia in a Rat Model of Full Thickness Thermal Injury

Objective

Opioid-based analgesics are a major component of the lengthy pain management of burn patients, including military service members, but are problematic due to central nervous system-mediated side effects. Peripheral analgesia via targeted ablation of nociceptive nerve endings that express the transient receptor potential vanilloid channel 1 (TRPV1) may provide an improved approach. We hypothesized that local injection of the TRPV1 agonist resiniferatoxin (RTX) would produce long-lasting analgesia in a rat model of pain associated with burn injury.

Methods

Baseline sensitivities to thermal and mechanical stimuli were measured in male and female Sprague-Dawley rats. Under anesthesia, a 100 °C metal probe was placed on the right hind paw for 30 seconds, and sensitivity was reassessed 72 hours following injury. Rats received RTX (0.25 μg/100 μL; ipl) into the injured hind paw, and sensitivity was reassessed across three weeks. Tissues were collected from a separate group of rats at 24 hours and/or one week post-RTX for pathological analyses of the injured hind paw, dorsal spinal cord c-Fos, and primary afferent neuropeptide immunoreactivity.

Results

Local RTX reversed burn pain behaviors within 24 hours, which lasted through recovery at three weeks. At one week following RTX, decreased c-Fos and primary afferent neuropeptide immunoreactivities were observed in the dorsal horn, while plantar burn pathology was unaltered.

Conclusions

These results indicate that local RTX induces long-lasting analgesia in a rat model of pain associated with burn. While opioids are undesirable in trauma patients due to side effects, RTX may provide valuable long-term, nonopioid analgesia for burn patients.

The Roles of Opioid Receptors in Cutaneous Wound Healing

The process of recovery from skin wounding can be protracted and painful, and scarring may lead to weakness of the tissue, unpleasant sensations such as pain or itch, and unfavorable cosmetic outcomes. Moreover, some wounds simply fail to heal and become a chronic burden for the sufferer. Understanding the mechanisms underlying wound healing and the concomitant sensory disorders and how they might be manipulated for therapeutic benefit has attracted much interest in recent years, and here we discuss the latest developments in the field, focusing on the emergent roles of the peripheral opioid receptor (OPr) system.

The Burn Wound Microenvironment

Significance: While the survival rate of the severely burned patient has improved significantly, relatively little progress has been made in treatment or prevention of burn-induced long-term sequelae, such as contraction and fibrosis. Recent Advances: Our knowledge of the molecular pathways involved in burn wounds has increased dramatically, and technological advances now allow large-scale genomic studies, providing a global view of wound healing processes. Critical Issues: Translating findings from a large number of in vitro and preclinical animal studies into clinical practice represents a gap in our understanding, and the failures of a number of clinical trials suggest that targeting single pathways or cytokines may not be the best approach. Significant opportunities for improvement exist. Future Directions: Study of the underlying molecular influences of burn wound healing progression will undoubtedly continue as an active research focus. Increasing our knowledge of these processes will identify additional therapeutic targets, supporting informed clinical studies that translate into clinical relevance and practice.

Progress of clinical practice on the management of burn-associated pain: Lessons from animal models

Opioid-based analgesics provide the mainstay for attenuating burn pain, but they have a myriad of side effects including respiratory depression, nausea, impaired gastrointestinal motility, sedation, dependence, physiologic tolerance, and opioid-induced hyperalgesia. To test and develop novel analgesics, validated burn-relevant animal models of pain are indispensable. Herein we review such animal models, which are mostly limited to rodent models of burn-induced, inflammatory, and neuropathic pain. The latter two are pain syndromes that provide insight into the pain caused by systemic pro-inflammatory cytokines and direct injury to nerves (e.g., after severe burn), respectively. To date, no single animal model optimally mimics the complex pathophysiology and pain that a human burn patient experiences. No currently available burn-pain model examines effects of pharmacological intervention on wound healing. As cornerstones of pain and wound healing, pro-inflammatory mediators may be utilized for insight into both processes. Moreover, common clinical concerns such as systemic inflammatory response syndrome and multiple organ dysfunction remain unaddressed. For development of analgesics, these aberrations can significantly alter the potential efficacy and/or adverse effects of a prescribed analgesic following burn trauma. We therefore suggest that a multi-model strategy would be the most clinically relevant when evaluating novel analgesics for use in burn patients.

Peripheral administration of morphine attenuates postincisional pain by regulating macrophage polarization through COX-2-dependent pathway

BACKGROUND

Macrophage infiltration to inflammatory sites promotes wound repair and may be involved in pain hypersensitivity after surgical incision. We recently reported that the development of hyperalgesia during chronic inflammation is regulated by macrophage polarity, often referred to as proinflammatory (M1) or anti-inflammatory (M2) macrophages. Although opioids such as morphine are known to alter the inflammatory milieu of incisional wounds through interactions with immunocytes, the macrophage-mediated effects of morphine on the development of postincisional pain have not been well investigated. In this study, we examined how morphine alters pain hypersensitivity through phenotypic shifts in local macrophages during the course of incision-induced inflammation.

RESULTS

Local administration of morphine in the early phase, but not in the late phase alleviated mechanical hyperalgesia, and this effect was reversed by clodronate-induced peripheral depletion of local macrophages. At the morphine-injected incisional sites, the number of pro-inflammatory F4/80+iNOS+M1 macrophages was decreased during the course of pain development whereas increased infiltration of wound healing F4/80+CD206+M2 macrophages was observed during the early phase. Morphine increased the gene expression of endogenous opioid, proenkephalin, and decreased the pronociceptive cytokine, interleukin-1β. Heme oxygenase (HO)-1 promotes the differentiation of macrophages to the M2 phenotype. An inhibitor of HO-1, tin protoporphyrin reversed morphine-induced analgesic effects and the changes in macrophage phenotype. However, local expression levels of HO-1 were not altered by morphine. Conversely, cyclooxygenase (COX)-2, primarily produced from peripheral macrophages in acute inflammation states, was up-regulated in the early phase at morphine-injected sites. In addition, the analgesic effects and a phenotype switching of infiltrated macrophages by morphine was reversed by local administration of a COX inhibitor, indomethacin.

CONCLUSIONS

Local administration of morphine alleviated the development of postincisional pain, possibly by altering macrophage polarity at the incisional sites. A morphine-induced shift in macrophage phenotype may be mediated by a COX-2-dependent mechanism. Therefore, μ-opioid receptor signaling in macrophages may be a potential therapeutic target during the early phase of postincisional pain development.

Therapy of Ulcerated Hemangiomas

Background:

Cutaneous ulceration is the most common complication of infantile hemangiomas (IHs) seen in a pediatric dermatology practice.

Objective:

The most effective treatments in our experience are compared to those in the current literature.

Methods:

The study was a retrospective chart review of therapy of 169 ulcerated IHs at a tertiary care pediatric hospital and a literature review.

Results:

Combination therapy was the rule. Local wound care was required in all, pain management in 72%, pulsed dye laser in 42%, infection control in 38%, diminution of the hemangioma through systemic therapy in 36%, and suppression of bleeding in 2%.

Limitations:

A retrospective review compared to a case-control study has inherent bias. In addition, our cases were all at a tertiary referral center.

Conclusion:

All ulcerated IHs benefit from local barrier creams or dressings. Pulsed dye laser, antibiotics, topical morphine 0.1% in hydrogel, topical becaplermin, and, most importantly, systemic therapy (especially propranolol) to reduce the hemangioma may be useful.

Targeting inflammation and wound healing by opioids

Opioid receptors are expressed on peripheral sensory nerve endings, cutaneous cells, and immune cells; and local application of opioids is used for the treatment of inflammatory pain in arthritis, burns, skin grafts, and chronic wounds. However, peripherally active opioids can also directly modulate the inflammatory process and wound healing. Here, we discuss the underlying mechanisms of opioid action and the conceivable therapeutic approaches for opioid treatment, as investigated in experimental and clinical studies. A large number of in vitro experiments and animal model investigations have produced evidence that peripherally active opioids can reduce plasma extravasation, vasodilation, proinflammatory neuropeptides, immune mediators, and tissue destruction. In contrast to currently available anti-inflammatory agents, opioids have not demonstrated organ toxicity, thus making them interesting candidates for drug development. Few clinical studies have tapped into this potential to date.

Surgically induced neuropathic pain: understanding the perioperative process

Nerve damage takes place during surgery. As a consequence, significant numbers (10%-40%) of patients experience chronic neuropathic pain termed surgically induced neuropathic pain (SNPP). The initiating surgery and nerve damage set off a cascade of events that includes both pain and an inflammatory response, resulting in "peripheral and central sensitization," with the latter resulting from repeated barrages of neural activity from nociceptors. In affected patients, these initial events produce chemical, structural, and functional changes in the peripheral and central nervous systems (CNS). The maladaptive changes in damaged nerves lead to peripheral manifestations of the neuropathic state-allodynia, sensory loss, shooting pains, etc, that can manifest long after the effects of the surgical injury have resolved. The CNS manifestations that occur are termed "centralization of pain" and affect sensory, emotional, and other (eg, cognitive) systems as well as contributing to some of the manifestations of the chronic pain syndrome (eg, depression). Currently there are no objective measures of nociception and pain in the perioperative period. As such, intermittent or continuous pain may take place during and after surgery. New technologies including direct measures of specific brain function of nociception and new insights into preoperative evaluation of patients including genetic predisposition, appear to provide initial opportunities for decreasing the burden of SNPP, until treatments with high efficacy and low adverse effects that either prevent or treat pain are discovered.

Influence of sleep deprivation and morphine on the expression of inducible nitric oxide synthase and cyclooxygenase-2 in skin of hairless mice

Skin performs a host of primordial functions that keep the body alive. Morphine is a drug with immunosuppressant properties whose chronic use may lead to increased infection and delayed wound healing. Sleep is a fundamental biological phenomenon that promotes the integrity of several bodily functions. Sleep deprivation adversely affects several systems, particularly the immune system. The aim of this study was to perform an immunohistochemical evaluation on the expression of inducible nitric oxide synthase and cyclooxygenase-2 in skin of sleep-deprived mice and mice chronically treated with morphine. Adult hairless male mice were distributed into the following groups: Control, morphine, sleep-deprived, and morphine + SD. Morphine (10 mg/kg, subcutaneous) was injected every 12 h for 9 days. Morphine induced immunoexpression of cyclooxygenase-2 and nitric oxide synthase. Sleep deprivation did not modulate outcomes induced by morphine. Morphine, not sleep loss, induces cyclooxygenase-2 and nitric oxide synthase immunoexpression in the skin of hairless mice.

Effect of opium dependency on secondary intention wound healing in a rat model: an experimental study

Opium dependency is a social and health problem in some middle eastern countries like Iran. Many of these people may require surgery. This study investigates the effects of opium dependency on histological parameters of secondary intention wound healing in rat. A full-thickness wound (2 × 2 cm in diameters) was created on the dorsum of two groups of rats, a normal control group and a second group of rat depended to opium (Badawy's method). Several times during 14 days postwounding, the wound was excised with peripheral margins of normal skin and was evaluated for cellular population, reepithelialisation and revascularisation. Results are presented as the mean ± standard error. Data were compared by an unpaired t-test or analysis of variance. Histological examination of the wound tissue showed evidence of increased population of fibroblasts, decreased recruitment of neutrophile and plateau of macrophage cells in opium depended animals comparing with control group. In the depended animals, reepithelialisation was seen to be enhanced significantly, while prohibiting progression of revascularisation. This study shows that opium dependency enhances reepitheliazation as well as tissue recruitment of fibroblasts; thereby probable enhancement of secondary intention wound healing.

Pharmacology of peripheral opioid receptors

PURPOSE OF REVIEW

Since the detection of morphine by the pharmacologist Friedrich Sertürner in 1806, opioids have been used as potent centrally acting analgesics. In addition to the central site of action, peripheral endogenous opioid analgesic systems have been extensively studied, especially in the past two decades. This review is not only mentioned to give a brief summary in this well investigated field of peripheral opioid receptors, but also to highlight the role of peripheral opioid receptors in other physiological and pathophysiological conditions.

RECENT FINDINGS

A number of studies, which initially focused on nociception, also revealed an important role of the peripheral opioid receptor system in opioid-induced bowel dysfunction and pruritus, as well as in wound healing, cardioprotection, and the analgesic effects of celecoxib.

SUMMARY

Efforts continue to develop opioid analgesics unable to cross the blood-brain barrier, which act only peripherally in low doses, thus providing adequate analgesia without central and systemic side-effects.The awareness of the influence of peripheral opioid receptors beyond nociception may also have therapeutic ramifications on the other fields mentioned above. For example, the treatment of opioid-induced bowel dysfunction by methylnaltrexone is one of the major findings in the previous years.

Should topical opioid analgesics be regarded as effective and safe when applied to chronic cutaneous lesions?

Objectives

The induction of analgesia for many chronic cutaneous lesions requires treatment with an opioid analgesic. In many patients suffering with these wounds such drugs are either contraindicated or shunned because of their association with death. There are now case reports involving over 100 patients with many different types of chronic superficial wounds, which suggest that the topical application of an opioid in a suitable gel leads to a significant reduction in the level of perceived pain.

Key findings

Some work has been undertaken to elucidate the mechanisms by which such a reduction is achieved. To date there have been no proven deleterious effects of such an analgesic system upon wound healing. Although morphine is not absorbed through the intact epidermis, an open wound provides no such barrier and for large wounds drug absorption can be problematic. However, for most chronic cutaneous lesions, where data has been gathered, the blood levels of the drug applied ranges from undetectable to below that required for a systemic effect.

Summary

If proven, the use of opioids in this way would provide adequate analgesia for a collection of wounds, which are difficult to treat in patients who are often vulnerable. Proof of this concept is now urgently required.

Effect of opium dependency on burn healing in a rat model: an experimental study

OBJECTIVE

This study aimed to investigate the effect of opium dependency on the healing of third-degree burns in rats.

MATERIAL AND METHODS

Twenty-four rats were randomly divided to experimental and control groups. In the experimental group, opium was added to the drinking water for 21 days at increasing concentrations. The control group did not receive opium. To prove dependency on opium in the rats, naloxone was injected intraperitoneally. Full-thickness burn wounds were inflicted by applying an iron cuboid preheated to 94°C to the flank of all rats for 20 s. On day 14 after burn injury, full-thickness biopsies were taken. Blind histopathologic evaluation was performed to assess length and thickness of the re-epithelialization area, number of neutrophils, fibroblasts, mononuclear cells and new vessels, and percentage of tissue in repair (neutrophilic exudate, and granulation and fibrous tissue). Findings were analyzed using SPSS software.

RESULTS

The wound surface area was 95 ± 43.35 mm(2) in the control group and 120.4 ± 50.12 mm(2) in the experimental group (p = 0.224). The findings show that opium dependency has no significant effect on the healing of burn wounds in rats except for the number of monocytes on day 14 (p < 0.05).

CONCLUSION

Morphine dependency does not seem to be as effective on third-degree burn healing.

3D-wound healing model: influence of morphine and solid lipid nanoparticles

For efficient pain reduction in severe skin wounds, topically applied opioids may be a new option. Moreover, by stimulating keratinocyte migration opioids may also accelerate wound healing. Yet, conventional formulations failed to consistently provide sufficient pain control in patients which may be due to local drug degradation or insufficient concentrations at the target site. After having excluded major morphine glucuronidation by keratinocytes and fibroblasts, we next aimed for an optimised formulation. Since long intervals for painful wound dressing changes are intended, the formulations should allow for prolonged opioid release and should not impair the healing process. We developed morphine-loaded solid lipid nanoparticles (SLN, mean size about 180 nm), and tested improvement of wound closure in a new human-based 3D-wound healing model. Standardised wounds were induced by CO(2)-laser irradiation of reconstructed human full-thickness skin equivalents (EpiDermFT). Morphine, morphine-loaded and unloaded SLN accelerated reepithelialization. Keratinocytes almost completely covered the dermis equivalent after 4 days, which was not the case when applying the vehicle. In conclusion, acceleration of wound closure, low cytotoxicity and irritation as well as possible prolonged morphine release make SLN an interesting approach for innovative wound management.

Delayed onset of changes in soma action potential genesis in nociceptive A-beta DRG neurons in vivo in a rat model of osteoarthritis

BACKGROUND

Clinical data on osteoarthritis (OA) suggest widespread changes in sensory function that vary during the progression of OA. In previous studies on a surgically-induced animal model of OA we have observed that changes in structure and gene expression follow a variable trajectory over the initial days and weeks. To investigate mechanisms underlying changes in sensory function in this model, the present electrophysiological study compared properties of primary sensory nociceptive neurons at one and two months after model induction with properties in naïve control animals. Pilot data indicated no difference in C- or Adelta-fiber associated neurons and therefore the focus is on Abeta-fiber nociceptive neurons.

RESULTS

At one month after unilateral derangement of the knee by cutting the anterior cruciate ligament and removing the medial meniscus, the only changes observed in Abeta-fiber dorsal root ganglion (DRG) neurons were in nociceptor-like unresponsive neurons bearing a hump on the repolarization phase; these changes consisted of longer half width, reflecting slowed dynamics of AP genesis, a depolarized Vm and an increased AP amplitude. At two months, changes observed were in Abeta-fiber high threshold mechanoreceptors, which exhibited shorter AP duration at base and half width, shorter rise time and fall time, and faster maximum rising rate/maximum falling rate, reflecting accelerated dynamics of AP genesis.

CONCLUSION

These data indicate that Abeta nociceptive neurons undergo significant changes that vary in time and occur later than changes in structure and in nociceptive scores in this surgically induced OA model. Thus, if changes in Abeta-fiber nociceptive neurons in this model reflect a role in OA pain, they may relate to mechanisms underlying pain associated with advanced OA.

Morphine-induced early delays in wound closure: involvement of sensory neuropeptides and modification of neurokinin receptor expression

Dose-limiting side effects of centrally acting opioid drugs have led to the use of topical opioids to reduce the pain associated with chronic cutaneous wounds. However, previous studies indicate that topical morphine application impairs wound healing. This study was designed to elucidate the mechanisms by which morphine delays wound closure. Rats were depleted of sensory neuropeptides by treatment with capsaicin, and full-thickness 4-mm diameter wounds were excised from the intrascapular region. Wounds were treated topically twice daily with 5mM morphine sulfate, 1mM substance P, 1mM neurokinin A, or 5mM morphine combined with 1mM substance P or neurokinin A and wound areas assessed. During closure, wound tissue was taken 1, 3, 5, and 8 days post-wounding from control and morphine-treated rats and immunostained for neurokinin receptors and markers for macrophages, myofibroblasts, and vasculature. Results obtained from capsaicin-treated animals demonstrated a significant delay in the early stages of wound contraction that was reversed by neuropeptide application. Treatment of capsaicin-treated rats with topical morphine did not further delay wound closure, suggesting that topical opioids impair wound closure via the inhibition of peripheral neuropeptide release into the healing wound. Morphine application altered neurokinin-1 and neurokinin-2 receptor expression in inflammatory and parenchymal cells essential for wound healing in a cell-specific manner, demonstrating a direct effect of morphine on neurokinin receptor regulation within an array of cells involved in wound healing. These data provide evidence indicating a potentially detrimental effect of topical morphine application on the dynamic wound healing process.