An assessment of the centrally acting muscle relaxant tolperisone on driving ability and cognitive effects compared to placebo and cyclobenzaprine

Postoperative analgesic options after spine surgery: finding the optimal treatment strategies

INTRODUCTION

Spine surgery is one of the most common types of surgeries performed in the United States; however, managing postoperative pain following spine surgery has proven to be challenging. Patients with spine pathologies have higher incidences of chronic pain and resultant opioid use and potential for tolerance. Implementing a multimodal plan for postoperative analgesia after spine surgery can lead to enhanced recovery and outcomes.

AREAS COVERED

This review presents several options for analgesia following spine surgery with an emphasis on multimodal techniques to best aid this specific patient population. In addition to traditional therapeutics, such as acetaminophen, non-steroidal anti-inflammatory medications, and opioids, we discuss intrathecal morphine administration and emerging regional anesthesia techniques.

EXPERT OPINION

Several adjuncts to improve analgesia following spine surgery are efficacious in the postoperative period. Intrathecal morphine provides sustained analgesia and can be instilled intraoperatively by the surgical team under direct visualization. Local anesthetics deposited under ultrasound guidance by an anesthesiologist trained in regional techniques also provide the opportunity for single injections or continuous analgesia via an indwelling catheter.

RESUME-1: a Phase III study of tolperisone in the treatment of painful, acute muscle spasms of the back

Tolperisone is a nonopioid, centrally acting muscle relaxant in clinical development in the USA for the treatment of symptoms associated with acute, painful muscles spasms of the back. CLN-301, RESUME-1, is a 14-day double-blind, randomized, placebo-controlled, parallel-group Phase III study of the efficacy and safety of tolperisone administered orally three-times daily in 1000 male and female subjects at approximately 70 clinical sites in the USA experiencing back pain due to or associated with muscle spasm of acute onset. Tolperisone is a promising therapeutic for managing acute, painful muscle spasms of the back as it appears to lack the off-target CNS effects often seen with conventional skeletal muscle relaxants. Clinical Trials Registration: NCT04671082.

Tolperisone for the Treatment of Acute Muscle Spasm of the Back: Results from the Dose-Ranging Phase 2 STAR Study (NCT03802565)

Objective

Use of skeletal muscle relaxants (SMRs) for acute muscle spasm is confounded by central nervous system adverse events (AEs), including somnolence. Tolperisone is an SMR that does not appear to be associated with somnolence. The aim of this study was to assess the safety and efficacy of tolperisone versus placebo in subjects with acute muscle spasm of the back.

Methods

STAR (NCT03802565) was a double-blind, randomized, placebo-controlled phase 2 study in subjects with back pain due to acute muscle spasm. Subjects were randomized 1:1:1:1:1 to tolperisone 50, 100, 150, or 200 mg three times daily (TID) or placebo for 14 days. The primary efficacy endpoint was subject-rated pain "right now" using a numeric rating scale on day 14.

Results

Subjects (tolperisone, n=337; placebo, n=78) were enrolled at 38 US clinical sites. Tolperisone was well tolerated, with AEs in 18.1% of subjects receiving tolperisone versus 14.1% of subjects receiving placebo. Headache (7.1%) and diarrhea (2.4%) were the most frequent AEs in tolperisone-treated subjects versus 3.8% and 0%, respectively, in placebo-treated subjects. Somnolence was reported in 1.2% and 2.6% of subjects treated with tolperisone and placebo, respectively. Mean change from baseline in numeric rating scale score of pain "right now" on day 14 was -3.5 for placebo versus -4.2, -4.0, -3.7, and -4.4 for tolperisone 50, 100, 150, and 200 mg TID, respectively (linear test of trend on the least-squares mean difference [treatment-placebo]; p=0.0539). In an analysis of pairwise estimates (treatment-placebo), the greatest numerical difference and significance were observed for tolperisone 200 mg TID (p=0.0040). Several secondary endpoints trended toward significance for tolperisone 200 mg TID versus placebo.

Conclusion

Tolperisone 200 mg TID may be a promising treatment for acute muscle spasm, without the somnolence associated with SMRs. The safety and efficacy of tolperisone should be evaluated in a phase 3 trial.

An assessment of the centrally acting muscle relaxant tolperisone on driving ability and cognitive effects compared to placebo and cyclobenzaprine

WHAT IS KNOWN AND OBJECTIVE

Tolperisone is a centrally acting muscle relaxant under development in the United States as a treatment for acute and painful symptoms of muscle spasms. The objective of this three-way, randomized, blinded, three-period crossover study was to assess the safety and cognitive effects of tolperisone compared to placebo and the widely used muscle relaxant cyclobenzaprine in healthy volunteers.

METHODS

Subjects were randomized to 1 of 3 treatment arms to receive tolperisone (150 mg), cyclobenzaprine (10 mg) or placebo 3 times per day (TID) in 3 separate study periods. Subjects completed a driving test on the Cognitive Research Corporation's Driving Simulator (CRCDS Mini-Sim), a validated driving simulator, on day 1 at time to maximum plasma concentration, on day 2 before the morning dose of study drug and on day 3 at steady state following the morning dose. Subjects were assessed on various driving parameters and on a computer-administered digit-symbol substitution test (CogScreen symbol digit coding test). The driving scenario is a monotonous 100 km highway route on which subjects are instructed to maintain speed and lane position.

RESULTS AND DISCUSSION

The performance of subjects who had received tolperisone was not significantly different from those who had received placebo in terms of the primary end point: standard deviation of lateral position, a measure of weaving. Subjects who had received tolperisone also performed comparably to those who had received placebo on a range of secondary measures assessing driving ability, cognition and psychomotor performance. In contrast, subjects who had received cyclobenzaprine showed significant impairment compared to placebo (P < .01) on the primary end point of standard deviation of lateral position and on the majority of the secondary end points of driving ability. Despite their markedly poorer driving performance after receiving cyclobenzaprine, few subjects reported feeling unsafe to drive on day 1 (10.3%) and day 2 (3.4%). The incidence of adverse events was similar for tolperisone (36.4%) and placebo (29.0%) and was greater for cyclobenzaprine (45.4%).

WHAT IS NEW AND CONCLUSION

Subjects who received tolperisone (150 mg TID) experienced no impact on various measures of driving, self-reported sleepiness and cognition measures compared to placebo, in contrast to those who received the widely used muscle relaxant cyclobenzaprine (10 mg TID).