The Non-Opioid Pain Patch

Pain complaints are among the most common reasons patients visit emergency departments. As the epidemic of opioid abuse and misuse continues to balloon, healthcare providers are looking for safer, non-addicting analgesics to prescribe to patients with pain. The lidocaine patch is one such option that is effective for certain types of pain. It is safe and well-tolerated, with little risk for systemic side effects and drug interactions. It can be used for an extended period of time without developing tolerance, physical dependence, or addiction. This all sounds great. But how well does it really work? And what sorts of patients does a lidocaine patch help? We’ll dive into that here.

The lidocaine patch is a 10 cm x 14 cm medicated patch with 5% lidocaine-containing hydrogel adhesive which is placed on the painful area. Lidocaine is continuously released at the site of application, and, unlike injected lidocaine, exerts local analgesic effects without causing numbness. A further benefit is that only a very small fraction of the dose ever reaches the systemic circulation, making it an attractive option for elderly patients and/or patients on multiple medications for which drug interactions are a concern [1].

Transdermal lidocaine is FDA-approved for the treatment of post-herpetic neuralgia. However it has also been evaluated in other neuropathic and non-neuropathic painful conditions, including diabetic polyneuropathy, osteoarthritis, pain from rib fractures, and low back pain.

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How Well Does It Work?
A Cochrane meta-analysis of 12 placebo-controlled studies of topical lidocaine for a variety of indications concluded there was “some indication that topical lidocaine offered benefit;” however the quality of evidence was rated as poor, largely reflecting the fact that the trials were subject to bias due to small numbers of enrollees [2].

Looking more closely, the strongest data on the lidocaine patch is for post-herpetic neuralgia [^3-5]. A multicenter double-blind, placebo-controlled study including 268 enrollees reported that treatment with 5% lidocaine patch was associated with clinically relevant improvements in allodynia, quality of life, and sleep quality [6]. Another interesting finding from a case review of patients with post-herpetic neuralgia was that treatment with the 5% lidocaine patch was associated with a 66% decrease in size of the painful area after 3 months, suggesting that long-term treatment might reverse central sensitization and reduce the receptive field zone.This result was duplicated in a study of patients with neuropathy that developed following traumatic injuries [6].

Diabetic polyneuropathy, another notoriously difficult condition to treat, may also respond to this medication. Studies have demonstrated improved pain scores and quality of life measures in patients with diabetic polyneuropathy treated with lidocaine patches. A meta-analysis reported similar improvements in pain scores when lidocaine patches were compared with amitriptyline, capsaicin, gabapentin, and pregabalin [^6,7]. The patches can be cut into pieces and placed on the areas of maximal pain, with a goal of covering the entire painful area. However this may not be practical if the symptoms are diffuse.

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Fibromyalgia is another difficult-to-treat condition which may respond to lidocaine. A randomized controlled trial of 60 patients with fibromyalgia reported a statistically significant decrease in pain symptoms with lidocaine patches, comparable to that of injected lidocaine at trigger points [8]. Additional trials report improvements in pain scores in patients with rib fractures, osteoarthritis, and low back pain [^9,10]. These conditions are common in the emergency department, and having an effective, non-opioid option for treatment of pain is appealing. Patients should be instructed to place the patch directly over the site of maximal pain, provided the skin is not broken or abraded.

Mechanism of Action
Lidocaine decreases the nerve membrane permeability to sodium ions, thereby inhibiting depolarization and transmission of pain signals. There also appears to be a local cooling effect from the hydrogel.

Cautions
The patch should be applied to intact skin, and should not be used on broken, or inflamed skin. Topical lidocaine may produce additive effects in patients taking antiarrhythmic medications, such as amiodarone, mexiletine, and intravenous lidocaine, though the risk is thought to be low. Lidocaine is contraindicated if there is hypersensitivity to other amide anesthetics (e.g. bupivicaine, ropivicaine). Patients with allergy to ester anesthetics (procaine, tetracaine, benzocaine) have not shown any cross-reactivity with lidocaine [^11].

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Adverse Effects
Most adverse events are mild and limited to local irritation and sensitivity at the site of application. Lidocaine toxicity may occur at blood concentrations above 5 mcg/mL, but this is rare with topical application, and more likely if a higher than recommended dose is used, if the patch is applied to denuded or inflamed skin, or if the patch is worn longer than recommended [^11]. Lidocaine toxicity involves CNS and cardiovascular manifestations, including tingling of the lips, tinnitus, metallic taste, seizures, hypotension, bradycardia, and cardiovascular collapse. Lidocaine toxicity is treated with ACLS protocols, benzodiazepines for seizures, and intravenous lipid emulsion therapy.

Dosing and Adjustments
The patch is applied to the painful area and left on for 12 hours; then removed for 12 hours (12 hours on, 12 hours off). A third of patients report ongoing pain relief even when the patch is off, another third report a gradual increase in pain, and the final third report rapid return of pain within an hour of patch removal [1]. Depending on the size of the painful area, up to 3 patches can be used at a time.

The prescription 5% lidocaine patches can be expensive, and if cost is prohibitive, one alternative is to use the over-the-counter 4% lidocaine patches, marketed under the brand names Aspercreme and Salonpas. An even less expensive alternative is 5% lidocaine gel, also available over-the-counter, which can be applied directly to the painful area.

Special Considerations
Pregnancy category B – Adverse events were not observed in animal reproduction studies of injectable lidocaine. While injected lidocaine does cross the placenta, the amount of lidocaine absorbed topically is variable and the potential of reaching the fetus is unknown [^11].

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Breastfeeding
Lidocaine is excreted into breastmilk, but the amount of lidocaine available to the nursing infant is very low and not expected to cause adverse effects [^11].

Cost

• Lidoderm patch 5% – $15.00/patch
• Generic lidocaine patch – $10.00/patch
• OTC 30 g tube of lidocaine gel – $19.50
• Insurance companies may require prior authorization to fill lidocaine patch prescriptions, which can be prohibitive from the emergency department.

REFERENCES

1. Mick G, Correa-Illanes G. Topical pain management with the 5% lidocaine medicated plaster–a review. Curr Med Res Opin. 2012;28(6):937-951.
2. Derry S, Wiffen PJ, Moore RA, Quinlan J. Topical lidocaine for neuropathic pain in adults. The Cochrane Library. 2014.
3. Galer BS, Rowbotham MC, Perander J, Friedman E. Topical lidocaine patch relieves postherpetic neuralgia more effectively than a vehicle topical patch: Results of an enriched enrollment study. Pain. 1999;80(3):533-538.
4. Gammaitoni AR, Alvarez NA, Galer BS. Safety and tolerability of the lidocaine patch 5%, a targeted peripheral analgesic: A review of the literature. The Journal of Clinical Pharmacology. 2003;43(2):111-117.
5. Meier T, Wasner G, Faust M, et al. Efficacy of lidocaine patch 5% in the treatment of focal peripheral neuropathic pain syndromes: A randomized, double-blind, placebo-controlled study. Pain. 2003;106(1):151-158.
6. de León-Casasola OA, Mayoral V. The topical 5% lidocaine medicated plaster in localized neuropathic pain: A reappraisal of the clinical evidence. Journal of pain research. 2016;9:67.
7. Barbano RL, Herrmann DN, Hart-Gouleau S, Pennella-Vaughan J, Lodewick PA, Dworkin RH. Effectiveness, tolerability, and impact on quality of life of the 5% lidocaine patch in diabetic polyneuropathy. Arch Neurol. 2004;61(6):914-918.
8. Affaitati G, Fabrizio A, Savini A, et al. A randomized, controlled study comparing a lidocaine patch, a placebo patch, and anesthetic injection for treatment of trigger points in patients with myofascial pain syndrome: Evaluation of pain and somatic pain thresholds. Clin Ther. 2009;31(4):705-720.
9. Zink KA, Mayberry JC, Peck EG, Schreiber MA. Lidocaine patches reduce pain in trauma patients with rib fractures. Am Surg. 2011;77(4):438-442.
10. Burch F, Codding C, Patel N, Sheldon E. Lidocaine patch 5% improves pain, stiffness, and physical function in osteoarthritis pain patients: A prospective, multicenter, open-label effectiveness trial. Osteoarthritis and cartilage. 2004;12(3):253-255.
11. Lexicomp online: Lidocaine (topical). drug information. Uptodate.com.Web site. http://www-uptodate-com.libproxy.lib.unc.edu/contents/lidocaine-topical-drug-information?source=search_result&search=lidocaine%20patch&selectedTitle=1~150. Accessed December 15, 2016., 2016.