What are the indications, dosing schedule, contraindications, and adverse effects of the 5 % lidocaine (10 cm²) patch for adult neuropathic pain?

Lidocaine 5% Patch for Adult Neuropathic Pain

Apply up to 3-4 lidocaine 5% patches to intact skin covering the painful area for 12 hours daily, followed by a mandatory 12-hour patch-free interval, as first-line therapy for localized neuropathic pain conditions including postherpetic neuralgia, painful diabetic polyneuropathy, and cancer-related neuropathic pain. 1, 2

Primary Indications

Lidocaine 5% patches are recommended as first-line therapy for postherpetic neuralgia with exceptional efficacy (NNT = 2), with approximately 60% of patients achieving moderate to complete pain relief. 1, 2

Additional evidence-based indications include:

• Painful diabetic polyneuropathy, particularly for nighttime foot pain 1, 2
• Cancer-related neuropathic pain and myofascial pain 3, 2
• HIV-associated peripheral neuropathy 1
• Postsurgical or post-traumatic neuralgia 4
• Localized myalgias and arthralgias 2

The patches work best for well-localized pain and are unlikely to benefit widespread pain distribution or central neuropathic pain. 5

Dosing Schedule and Application Protocol

Standard regimen: Apply up to 3-4 patches simultaneously to intact skin for 12 hours, then remove for a mandatory 12-hour patch-free period within each 24-hour cycle. 1, 2, 5

Application specifics:

• Maximum coverage area: 420-560 cm² (depending on number of patches used) 6, 7
• Apply to dorsal or plantar surfaces of the affected area 1
• Patches can be worn during day or night based on patient preference 7
• Available as 5% prescription strength or 4% over-the-counter concentration 1, 2

Pain relief typically begins 30 minutes to 4 hours after application and is sustained throughout the 12-hour wearing period. 6

Absolute Contraindications

Do not use lidocaine patches in the following situations:

• Advanced liver failure or hepatic dysfunction - Lidocaine clearance decreases by 60% in liver dysfunction, creating systemic toxicity risk even with topical application 5
• Known hypersensitivity to amide-type local anesthetics - Risk of delayed-type hypersensitivity reactions 5
• Application to broken or inflamed skin - This dramatically increases systemic absorption and toxicity risk 1, 2, 5
• Application to open wounds - Manufacturers explicitly warn against this use 5

Relative Contraindications and Special Precautions

Exercise caution in patients with significant cardiac disease, as systemic absorption can theoretically cause cardiac arrhythmias and myocardial depression, though this risk is minimal with proper patch use. 5

Elderly patients (>70 years) remain safe candidates for lidocaine patches due to minimal systemic absorption, unlike systemic lidocaine which carries higher toxicity risk in this population. 5

No dose adjustment is required for renal impairment because lidocaine patches have minimal systemic absorption, unlike gabapentin and pregabalin which require renal dose adjustment. 5

Critical Safety Parameters and Common Pitfalls

Do not exceed 3-4 patches applied simultaneously, and never exceed 12 hours of continuous application. 5

Avoid excessive heat application over patches, as this increases systemic absorption. 1, 5

Do not use patches within 4 hours of other local anesthetic interventions to prevent cumulative toxicity. 5

Remove topical lidocaine patches before starting intravenous lidocaine therapy. 5

Monitor for signs of systemic absorption (rare but important):

• Dizziness and confusion 1, 5
• Drowsiness or altered consciousness 5
• Bradycardia 1, 5
• Muscle twitching 1, 5
• Perioral numbness 5

Adverse Effects Profile

Lidocaine patches demonstrate exceptional safety with minimal systemic absorption - the highest measured blood level with up to 4 patches applied for 24 hours was only 0.1 micrograms/ml, far below toxic thresholds. 6, 8

Most adverse events are mild and localized to the application site:

• Skin rash or irritation at patch site 5
• Application site reactions (erythema, pruritus) 8

The frequency of adverse events differs by anatomic location, with significantly more adverse events when patches are applied to the head versus trunk or extremities. 9

Systemic adverse effects are rare when patches are used correctly, with no clinically significant drug-drug interactions reported. 8

Combination Therapy Algorithm When Patches Alone Are Insufficient

If inadequate pain relief after 4 weeks of patch therapy, add gabapentin starting at 50-100 mg three times daily, titrating to 900-3600 mg daily for neuropathic pain components. 1, 2

Alternative escalation options:

• Pregabalin 50 mg three times daily, titrated to 100 mg three times daily if gabapentin fails 1, 2
• Capsaicin 8% patch for single application providing pain relief lasting up to 90 days 1, 2
• Tricyclic antidepressants (nortriptyline, desipramine) 10-25 mg starting dose, titrated to 50-150 mg 1

Lidocaine patches can be combined with opioids, antidepressants, and/or anticonvulsants as part of multimodal analgesia for neuropathic pain. 3, 5

Pharmacokinetics and Mechanism of Action

Lidocaine blocks sodium ion channels required for neuronal impulse initiation and conduction, providing local anesthesia without complete sensory block. 5

The patch delivers medication gradually over 12 hours with minimal systemic absorption - pharmacokinetic studies confirm systemic lidocaine levels remain within safe range even with four patches applied over 24 hours. 2, 6

Systemic absorption is even lower in PHN patients compared to healthy adults at the recommended dose. 8

Alternative Formulations

Lidocaine cream formulations may be used as an alternative when patch adhesion is problematic or when the affected area is small. 2

The 5% prescription patch may be more effective than cream or ointment due to its gradual delivery mechanism, providing sustained relief over 12 hours. 5