What is the rationale for the 12-hour on, 12-hour off application regimen of a lidocaine (local anesthetic) patch?

From the Guidelines

Lidocaine patches should be applied for 12 hours and then removed for 12 hours to minimize the risk of skin irritation, sensitization, and potential toxicity, as recommended by the most recent guidelines 1. The rationale behind this 12-on/12-off schedule is to balance effective pain relief with safety considerations. During the 12-hour application period, lidocaine is absorbed through the skin, blocking sodium channels in pain neurons and reducing pain signals. However, prolonged continuous contact with the skin can lead to irritation, redness, and allergic reactions in some patients.

• The 12-hour break prevents systemic accumulation of lidocaine, which could potentially cause side effects like dizziness, numbness, or in rare cases, cardiac issues if levels become too high 1.
• The drug continues to provide analgesic effects even after removal due to its residual presence in skin tissues.
• For optimal benefit, patients should rotate application sites and ensure the skin is clean and dry before applying a new patch. This cycling approach is supported by the most recent guidelines, which emphasize the importance of minimizing adverse effects while providing effective pain management 1.
• Patient factors, such as low body weight or high body mass index (BMI), may also influence lidocaine toxicity, and should be taken into consideration when using lidocaine patches 1.
• Additionally, drug interactions, such as those with beta-blockers or amiodarone, may enhance lidocaine toxicity, and should be monitored closely 1.

From the Research

Rationale for 12-Hour On, 12-Hour Off Application Regimen

The rationale for the 12-hour on, 12-hour off application regimen of a lidocaine patch can be understood by considering the following points:

• Pharmacokinetics: Studies have shown that the application of lidocaine patches for 12 hours allows for the penetration of lidocaine into the skin, producing an analgesic effect without producing a complete sensory block 2.
• Adhesion Performance: The adhesion performance of lidocaine patches is critical for their effectiveness. A study comparing the adhesion performance of a 1.8% lidocaine topical system with 5% lidocaine patches found that the 1.8% system demonstrated superior adhesion performance over 12 hours 3.
• Heat and Application Time: Research has investigated the effects of heat and application time on the pharmacokinetic properties of lidocaine patches. One study found that the heated patch continuously delivered drug for up to 12 hours and was generally well tolerated in healthy subjects 4.
• Analgesic Effect: The analgesic effect of lidocaine patches has been demonstrated in various studies. For example, a double-blind, vehicle-controlled study found that lidocaine patch 5% produced significant pain relief in patients with acute herpes zoster 5.
• Safety and Tolerability: The safety and tolerability of lidocaine patches have been evaluated in several studies. A pharmacokinetic study found that continuous application of four lidocaine patches 5% for 72 hours, changed every 12 or 24 hours, produced plasma lidocaine concentrations that remained well below those that typically produce antiarrhythmic effects or toxicity 6.

Key Findings

• Lidocaine patches produce an analgesic effect without producing a complete sensory block 2.
• The 1.8% lidocaine topical system demonstrates superior adhesion performance over 12 hours compared to 5% lidocaine patches 3.
• The heated patch continuously delivers drug for up to 12 hours and is generally well tolerated in healthy subjects 4.
• Lidocaine patch 5% produces significant pain relief in patients with acute herpes zoster 5.
• Continuous application of lidocaine patches for 72 hours produces plasma lidocaine concentrations that remain well below those that typically produce antiarrhythmic effects or toxicity 6.