What are transdermal anesthetic patches?

From the Guidelines

Anesthetic patches are medically designed adhesive patches that deliver local anesthetic medication through the skin to numb a specific area of the body, with the most common type being the lidocaine patch, which typically contains 5% lidocaine, as described in a recent study published in the Mayo Clinic Proceedings 1.

Key Characteristics of Anesthetic Patches

• They work by slowly releasing the anesthetic agent into the skin, blocking pain signals from nerve endings.
• They're primarily used for localized pain management, particularly for conditions like post-herpetic neuralgia (pain after shingles), musculoskeletal pain, and minor procedures.
• To use them, you simply apply the patch directly to intact skin over the painful area for up to 12 hours within a 24-hour period.
• The medication works locally with minimal systemic absorption, making side effects uncommon, as noted in guidelines for the use of local anesthesia in office-based dermatologic surgery 1.

Important Considerations

• They should not be applied to broken or irritated skin, and should be kept away from the eyes and mucous membranes.
• Unlike oral pain medications, these patches provide targeted relief without significant systemic effects, making them useful for patients who cannot tolerate oral medications or prefer localized treatment.
• Allergy to lidocaine is rare, but for patients with a true allergy, alternative options such as ester-type local anesthetics or diphenhydramine may be considered, as discussed in guidelines for the use of local anesthesia in office-based dermatologic surgery 1.

Recommendations for Use

• Lidocaine patches are a recommended option for localized pain management, particularly for conditions like post-herpetic neuralgia and musculoskeletal pain, due to their efficacy and safety profile, as supported by recent studies 1.
• Topical lidocaine is safe for use on pregnant or nursing women, but elective procedures should be postponed until after delivery, as recommended in guidelines for the use of local anesthesia in office-based dermatologic surgery 1.

From the FDA Drug Label

Purpose Topical Anesthetic The anesthetic patches are a type of topical anesthetic, as indicated by the drug label of lidocaine (TD) 2.

• They are used to produce numbness or loss of sensation in a specific area of the body.
• The directions for use are provided in the drug label of lidocaine (TD) 2, but do not explicitly define what anesthetic patches are.

From the Research

Definition and Purpose of Anesthetic Patches

• Anesthetic patches are topical formulations designed to deliver anesthetics, such as lidocaine, through the skin to provide localized pain relief 3, 4, 5.
• These patches are used to manage various types of pain, including post-herpetic neuralgia, lower back pain, carpal tunnel syndrome, diabetic peripheral neuropathy, and osteoarthritis joint pain 3.
• Anesthetic patches work by penetrating the skin and targeting peripheral nociceptive pathways, minimizing absorption into the plasma and reducing the risk of systemic adverse effects 3.

Types and Efficacy of Anesthetic Patches

• Lidocaine patches are a common type of anesthetic patch, available in different concentrations, such as 5% and 1.8% 3, 4.
• Studies have shown that lidocaine patches are effective in controlling musculoskeletal and neuropathic pain, with a minimal risk of toxicity or drug-drug interactions 3, 4.
• The efficacy of anesthetic patches has been demonstrated in various clinical trials, including a systematic review and meta-analysis that found lidocaine patches to be more effective than placebo patches in controlling acute localized pain 4.

Safety and Potential Side Effects

• Anesthetic patches are generally well-tolerated, with a low risk of adverse events, such as skin irritation or allergic reactions 3, 4, 6.
• However, some studies have reported cases of allergic reactions to topical anesthetics, including benzocaine and lidocaine 6.
• The safety of anesthetic patches has been evaluated in various studies, including a systematic review and meta-analysis that found no significant increase in the risk of local anesthetic-related side effects 7.

Clinical Applications and Guidelines

• Anesthetic patches are used in various clinical settings, including emergency departments, dental clinics, and pain management centers 4, 5, 7.
• Clinical practice guidelines, such as those from the American Academy of Neurology and the European Federation of Neurological Societies, support the use of topical lidocaine as a first-line treatment for post-herpetic neuralgia 3.
• The FDA has approved lidocaine patches for the treatment of pain secondary to post-herpetic neuralgia, and they are also used off-label for other types of pain management 3, 7.