Topical analgesics

Topical Delivery Systems Effectively Transport Analgesics to Areas of Localized Pain via Direct Diffusion

Topical delivery systems (TDSs) enable the direct transport of analgesics into areas of localized pain and thus minimize the side effects of administration routes that rely on systemic drug distribution. For musculoskeletal pain, clinicians frequently prescribe topical products containing lidocaine or diclofenac. This study assessed whether drug delivery from a TDS into muscle tissue occurs mainly via direct diffusion or systemic transport. An investigational TDS containing 108 mg lidocaine (SP-103, 5.4% lidocaine), a commercially available TDS containing 36 mg lidocaine (ZTlido®, 1.8% lidocaine), and a topical pain relief gel (Pennsaid®, 2% diclofenac) were tested. Using open flow microperfusion (OFM), interstitial fluid from the dermis, subcutaneous adipose tissue (SAT), and muscle was continuously sampled to assess drug penetration in all tissue layers. Ex vivo and in vivo experiments showed a higher diffusive transport of lidocaine compared to diclofenac. The data showed a clear contribution of diffusive transport to lidocaine concentration, with SP-103 5.4% resulting in a significantly higher lidocaine concentration in muscle tissue than commercially available ZTlido® (p = 0.008). These results indicate that SP-103 5.4% is highly effective in delivering lidocaine into muscle tissue in areas of localized pain for the treatment of musculoskeletal pain disorders (e.g., lower back pain).

Efficacy of Transdermal Ketoprofen Patch in Comparison to Transdermal Diclofenac Patch in Postoperative Analgesia for Orthodontic Extractions: A Randomized Split-Mouth Study

Introduction Non-steroidal anti-inflammatory drugs (NSAIDs) are the most prescribed analgesics for controlling post-exodontia pain, administered by various routes. The transdermal route possesses the advantages of providing sustained release of the drug, being non-invasive, bypassing first-pass metabolism, and eliminating gastrointestinal adverse effects. This study compared the analgesic efficacy of diclofenac 200 mg and ketoprofen 30 mg transdermal patches for post-orthodontic exodontia pain. Materials and methods Thirty patients who underwent orthodontic bilateral maxillary and/or mandibular premolar extractions under local anaesthesia were included in the study. Each patient received single transdermal diclofenac 200 mg patch and single transdermal ketoprofen 30 mg patch on the outer, ipsilateral upper arm immediately post-extraction in the two appointments in random order. The pain score was recorded every second hourly for the first 24 hours postoperatively using a visual analog scale (VAS). The requirement of rescue analgesics at various time points and the total number of rescue analgesics taken in the first 24 hours postoperatively were noted. Any allergic reaction to the transdermal patches was also recorded. Results The analgesic efficacy of the two transdermal patches at any given time point in 24 hours by Mann-Whitney U test showed no statistically significant (p<0.05) difference. An overall intragroup statistically significant difference (p<0.05), by Wilcoxon matched pairs test, was found by comparison of VAS pain scores at different time points to that at 0-2 hours after application of transdermal ketoprofen and diclofenac patches, respectively. The mean maximum pain intensity was slightly lower for ketoprofen (2.33) than diclofenac (2.60) transdermal patch. Patients consumed the rescue analgesic within the first 12 hours postoperatively, with the mean value of the total number of rescue analgesics taken with ketoprofen transdermal patch (0.23) slightly lower than diclofenac transdermal patch (0.27) application. Conclusion Ketoprofen and diclofenac transdermal patches provide similar analgesia post orthodontic extraction. The patients required rescue analgesics only during the initial hours of the postoperative follow-up period.

Efficacy of Lidocaine Topical Solution in Reducing Discomfort Reaction of Horses to Intramuscular Vaccination

Simple Summary

Intramuscular injection for vaccination and venipuncture for blood sampling are necessary for routine preventative health care for horses. A considerable proportion of horses react to these procedures, particularly as a needle pierces the skin. Many progress to become “needle shy.” Avoidance behaviors often quickly escalate to dangerous levels. Our clinical experience suggests that topical numbing solutions shown to reduce needle discomfort in other species also help horses better tolerate needles. To critically evaluate this clinical impression, 78 ponies were divided into three groups, each with either 5% or 10% lidocaine solution (commercially available preparations) or 0% control (sterile water) applied two minutes before each of two intramuscular vaccinations. Personnel handling the ponies, performing injections, scoring behavior reactions and analyzing data were unaware of treatment assignments. For both lidocaine treatments, behavioral reactions were lower than control treatment and not significantly different from one another. Fewer than 15% of lidocaine-treated ponies (7 of 51) had greater than a slight flinch reaction, compared to more than half (55%) of control group ponies (15 of 27). This clearly demonstrates that topical anesthetic can effectively reduce the behavior reaction of horses to intramuscular injection, providing convincing support for its routine use to improve animal welfare and care staff safety.

Abstract

Vaccinations via intramuscular injection are a key component of preventative health care in horses. Development of problematic behavioral aversion to injections is quite common. Our clinical impression has been that topical anesthetic applied to injection sites can reduce the behavioral reaction; however, this has not been critically tested. To blindly evaluate efficacy, either 5% or 10% topical lidocaine solution or 0% control was applied to injection sites for 78 ponies two minutes before intramuscular vaccination. Mean reaction scores on a scale of 0–3 were 0.84 (se 0.18) for 5% lidocaine solution, 0.62 (se 0.14) for 10% lidocaine solution, compared to 1.30 (se 0.19) for 0% control solution. Reaction scores for both the 5% and 10% lidocaine were significantly lower than for the control group. Additionally, the proportion of subjects with a reaction greater than a slight flinch was 2 of 25 for the 5% lidocaine, 5 of 26 for the 10% lidocaine and 15 of 27 for the 0% lidocaine control. For both the 5% and 10% lidocaine groups, the proportion differed significantly from the control. The difference between the 5% and 10% lidocaine groups was not statistically significant. These findings confirm our clinical impression that application of topical anesthetic just two minutes in advance of intramuscular injection can effectively reduce the behavior reaction of horses.

Comparison Between Efficacy of Transdermal Ketoprofen and Diclofenac Patch in Patients Undergoing Therapeutic Extraction-A Randomized Prospective Split Mouth Study

PURPOSE

Postoperative pain control is a significant aspect of patient treatment after an oral and maxillofacial surgical procedure. The use of a transdermal patch is one such method to provide postoperative analgesia. The present study was undertaken to investigate the efficacy of a single-dose transdermal patch of ketoprofen compared with that of diclofenac postoperatively after therapeutic extraction of first premolar teeth for patients undergoing orthodontic treatment.

PATIENTS AND METHODS

A split mouth randomized clinical trial was conducted of 40 patients aged 15 to 25 years who had required therapeutic extraction of both maxillary and mandibular first premolar teeth bilaterally. A single ketoprofen patch was applied for the first and fourth quadrant extraction, and diclofenac patch was applied for the second and third quadrant extraction after atraumatic therapeutic exodontia at 2 consecutive appointments with the patient under local anesthesia. The data were obtained and analyzed using the Student t test and Shapiro-Wilk test using SPSS software (IBM Corp, Armonk, NY).

RESULTS

All 40 patients who had received a single-dose ketoprofen patch had experienced less postoperative pain and did not require a rescue analgesic with a mean visual analog scale (VAS) score of 1.13 ± 0.335 (P < .00001). The patients who had received a diclofenac patch reported comparatively elevated pain scores in the initial 24 hours, with a mean VAS score of 2.0 ± 0.5064 postoperatively, and 20% of the diclofenac treatment arm had required a rescue analgesic. No complications were observed among the patients postoperatively in either treatment arm.

CONCLUSIONS

Both the ketoprofen and diclofenac transdermal patches were effective in achieving postoperative analgesia in patients after therapeutic extraction, with ketoprofen superior to diclofenac as a transdermal medicament.

Topical drug therapeutics for neuropathic pain

INTRODUCTION

Neuropathic pain (NP) is a particularly severe and intractable chronic condition that is not well treated by commonly recommended systemic pharmacological therapies, partly due to dose-limiting side effects or adverse events. The use of topical therapeutics for NP is growing and benefits from the reduced potential for adverse effects, as well as the ability to directly target peripheral pathological processes.

AREAS COVERED

The current review defines and describes the limitations of various commonly prescribed systemic pharmacological therapies for NP. It also provides a justification for increased research aimed at developing topical therapeutics for NP, particularly localized and peripheral NP. The review discusses the various classes of topical treatments used for NP, including agents that: block sensory inputs; activate inhibitory systems; provide mechanism-based therapeutics; are used in mucosal tissues; and include combinations that produce multimodal therapeutic effects.

EXPERT OPINION

There are arguments that the current topical therapeutics for NP rely too heavily on the use of local anesthetics and capsaicinoids, and more research is certainly needed on topical therapies that are multimodal and/or are targeted at the peripheral sources of pathology. The potential for novel topical therapeutics may be enhanced by further research on topical co-drugs, drug-drug salts, co-crystals and hydrates, and ionic liquids.

Efficacy of gabapentin in the improvement of pruritus and quality of life of patients with notalgia paresthetica

BACKGROUND

notalgia paresthetica is a subdiagnosed sensory neuropathy presenting as a condition of intense itching and hyperchromic macule on the back that interferes with daily habits.

OBJECTIVES

To determine the efficacy of treatment of notalgia paresthetica using oral gabapentin, assessing the degree of improvement in itching and influence on quality of life. Moreover, to evaluate the signs and symptoms associated with notalgia paresthetica.

METHODS

We conducted an experimental, non-randomized, parallel, non-blinded study including 20 patients with clinical and histopathological diagnosis of notalgia paresthetica. After application of the visual analogue scale of pain adapted for pruritus and of the questionnaire of dermatology life quality index (DLQI), ten patients with visual analogue scale > 5 were given treatment with gabapentin at the dose of 300 mg/day for four weeks. The other ten were treated with topical capsaicin 0.025% daily for four weeks. After the treatment period, patients answered again the scale of itching.

RESULTS

The use of gabapentin was responsible for a significant improvement in pruritus (p=0.0020). Besides itching and hyperchromic stain on the back, patients reported paresthesia and back pain. It was observed that the main factor in the worsening of the rash is heat.

CONCLUSION

Gabapentin is a good option for the treatment of severe itching caused by nostalgia paresthetica.

Chronic pain management in the cancer survivor: tips for primary care providers

Many cancer survivors suffer from chronic pain related to treatment. Pain management in the survivor is similar to chronic noncancer pain, with the important caveat that new or worsening pain must be promptly assessed for malignancy. This article reviews cancer survivorship, identifies common pain problems, and discusses strategies for management.

Topical analgesics

BACKGROUND AND OBJECTIVES

Pain treatment involves the usage of common and opioid analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs) and adjuvant analgesics. Traditionally, these drugs are administered systemically or into the neuraxis. However, when analgesics are applied through these pathways, they are associated with significant side effects, which can hinder its use. Topical administration of analgesics is an alternative. The objective of this paper is to discuss topical analgesics, the mechanisms of action and clinical efficacy.

CONTENT

This is a review paper addressing the usage of the topical local anesthetics: capsaicin, clonidine, tricyclic antidepressants, ketamine, opioids and cannabinoids, discussing mechanism of action and effectiveness.

CONCLUSIONS

Topical analgesics are promising as a strategy for pain treatment, as they are associated with lower incidence of side effects. The benefit of local anesthetics, NSAID's and capsaicin is well established. However, the efficacy of clonidine, tricyclic antidepressants, ketamine, opioids and cannabinoids is still questionable. Studies have shown that the multimodal approach is an alternative, but studies are needed to confirm this hypothesis.

Update on the use of topical NSAIDs for the treatment of soft tissue and musculoskeletal pain: a review of recent data and current treatment options

Topical nonsteroidal anti-inflammatory drugs (NSAIDs) have an emerging role in the treatment of certain types of acute pain. In addition to their convenience, efficacy, and safety, they are an attractive option, particularly when considering current concerns about the safety of traditional NSAIDs and cyclooxygenase-2 (COX-2) inhibitors (coxibs). Topical analgesics act largely within the peripheral nervous system. Studies have demonstrated that topical NSAIDs penetrate the skin and distribute to the target tissues underlying the application site. Because the pharmacologically effective dose is delivered at the site of pain, there is minimal systemic absorption and risk of related adverse events. Topical NSAIDs have been used for many years in Europe, with extensive post-marketing data available for some of the agents. Three topical NSAID formulations have recently been approved for use in the United States: the diclofenac epolamine topical patch 1.3% (DETP), diclofenac sodium 1% gel, and diclofenac sodium topical solution 1.5%. Topical NSAIDs provide a therapeutic option for treatment of acute, localized, soft tissue injuries or painful conditions in areas of the body that can be readily treated using the topical route of administration. This article reviews available data on the use of topical NSAID therapy.