Medi-Solfen^®, a topical analgesic, has the potential for use during pre-closure of surgical wounds in a multi-modal approach to post-surgical pain mitigation

In 2013/2014 there were 4.7 surgical admissions in England which represents a 27% increase since 2003/2004. Specialists with the highest activity include general surgery 1.3m, trauma/orthopaedics 1.2m and urology 736,000. The most common procedures were hernia repair (all forms) 120,000, hip replacement 116,000, knee replacement 82,000, gall bladder removal 76,000 and tonsillectomy 51,000. Emergency laparotomies are estimated to be 30,000-50,000 per annum¹. According to the latest data from the National Centre for Health Statistics, 48 million surgical inpatient procedures were performed in the United States in 2009².

Post-operative acute pain management is a major health issue and is costly to the health care system³. Pain contributes to poor quality of life, reduced well-being, physical disability and mortality⁴. One source of pain includes surgical procedures.

Unrelieved postsurgical pain is common and may be a useful context in which to study pain- related morbidity and mortality. For example, postoperative pain in hip fracture patients predicted longer hospital length of stay (LOS), delayed ambulation and long-term functional impairment⁵. Local anaesthetic (LA) infiltration prior to surgical incision closure is a frequently used technique in the operating room. The technique of injecting local anaesthetics into the various layers of the surgical incision (wound) is also a commonly used practice in general anaesthesia surgical cases⁶. Surgical wound infiltration with local anaesthetics has continued to increase in popularity since the mid 1990’s7. It is relatively inexpensive, technically not difficult and may potentially reduce the post-operative discomfort⁷.

Even though pain results from complex physiologic mechanisms that involve multiple receptors in both the central and peripheral nervous systems, single or monotherapy with opioids has been a foundation of postsurgical pain management. However, no single analgesic targets all types of pain receptors or signalling pathways; furthermore, the amount of opioids that can be administered is limited due to the risk for adverse drug events that lead to patient discomfort, delayed recovery, prolonged LOS, and increased costs⁸.

The use of multimodal analgesia involves the administration of two or more analgesic agents that act through different mechanisms with the goal of improving postsurgical pain management.

Non-opioid alternatives, e.g. NSAIDs, acetaminophen, and local anaesthetics are recognized as effective components of a multimodal pain regimen postoperatively. A multimodal approach can reduce opioid use and opioid-related adverse drug events and also result in earlier patient ambulation as well as discharge. Professional guidelines endorse the use of multimodal therapies which should be individualised for the particular patient, operation and circumstances. Understanding of both the range of available interventions and considering the type of surgical procedure are essential to safe and effective pain management. (Veterans Administration/Department of Defence (VA/DoD) Clinical Practice Guideline for the Management of Postoperative Pain). The guidelines also state that the selection of a pain management option should be determined by balancing the advantages, disadvantages, contraindications, as well as patient preference. For most patients, more than one modality will be needed for successful pain management.

Examples of local anaesthetics that are commonly infiltrated include moderate duration agents such as lidocaine, Mepivacaine and Prilocaine and long duration agents such as Bupivacaine and Etidocaine⁹. Local infiltration may however cause a haematoma to form if the needle damages a blood vessel. Other methods include use of a catheter to infuse local anaesthetic post operatively. This can be done through a catheter laid directly in the wound, or by a catheter placed in a key nerve region nearby (such as a paravertebral catheter placed at thoracotomy to block intercostal nerves at multiple levels). The catheter may stay 2 or 3 days after surgery. There are potential risks with this which include failure of the catheter to sit in the right spot and therefore be ineffective at delivering the local anaesthetic to the regional nerves, risk of infection tracking along the catheter track, or even the catheter being inadvertently retained by a wound closure suture passing through it (meaning re-operation to release the catheter).

Medi-Solfen® could provide a unique innovative approach to anaesthesia prior to surgical closure

Medi-Solfen® offers the surgeon a product that contains all of the components of multimodal therapy in one very simple to apply gel negating the need for individual injections associated with multimodal anaesthetic therapy. Medi-Solfen® is a sterile, cutaneous gel containing four well established active ingredients; lidocaine hydrochloride 5%w/w (equivalent to 4% lidocaine), 0.5%w/w bupivacaine hydrochloride, 0.00451%w/w adrenaline acid tartrate and 0.5%w/w cetrimide in a fixed combination product. As the active ingredients are well- established as local anaesthetics (lidocaine and bupivacaine), as a vasoconstrictor (adrenaline) and as an antiseptic (cetrimide) it offers a unique combination of ingredients not found together in any other product. Use of an agent like Medi-Solfen® can avoid the complications previously highlighted associated with the use of needles. These include no risk of haematoma from use of a needle for infiltration, no swelling of tissues from the volume of local anaesthetic injected around the wound, no catheter to need precise placement or to act as a hazardous foreign body. Additionally the application of Medi-Solfen® directly in onto the wound during closure may act as a “depot” for continued release of the local anaesthetic from the gel for a few hours afterwards.

References

1. https://www.rcseng.ac.uk/news-and-events/media-centre/media-background- briefings-and-statistics/surgery-and-the-nhs-in-numbers/
2. https://stanfordhealthcare.org/medical-clinics/surgery-clinic/patient-resources/surgery-statistics.html
3. Allegri M, Clark MR, De Andres J, et al. (2012) Acute and chronic pain: where we are and where we have to go. Minerva Anestesiol; 78: 222-235.
4. McGuire L, Heffner K, Glaser R et al. (2006). Pain and wound healing in surgical patients. Ann Behav Med;
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6. Morrison, RS, Magaziner J, McLaughlin et al. (2003) The impact of post-operative pain on outcomes following hip fracture. Pain; 103: 303-311.
7. Scott NB (2010) Wound infiltration for surgery. Anaesthesia 65 Suppl 1: 67-75.
8. Johnson RC, Hedges AR, Morris R, Stamatakis JD (1999) Ideal pain relief following laparoscopic cholecystectomy. Int J Clin Pract 53: 16-18.
9. Moss Rose (2015) Infiltration of local anaesthetics for Postoperative analgesia. Ongoing Education Initiative Pfeidler Enterprises.
10. Surgeon’s Guide to Postsurgical Pain Management: Colorectal and Abdominal Surgery, 1st ed. West Islip, NY: Professional Communications, Inc.; 201.)

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