The pharmacokinetics and pharmacodynamics of dexamethasone following epidural SP-102 or intravenous dexamethasone sodium phosphate injection in subjects with lumbosacral radicular pain.

OBJECTIVES: To evaluate the pharmacokinetics, pharmacodynamics (PD), safety, and tolerability of epidural SP-102 (10 mg dexamethasone sodium phosphate injectable gel) compared to an intravenous injection of 10 mg dexamethasone sodium phosphate, USP (IV USP). MATERIALS AND METHODS: Subjects with lumbosacral radiculopathy received a single dose of epidural SP-102, followed by a single dose of IV USP 4 weeks later. Dexamethasone plasma levels, cortisol levels, white blood cells (WBC), and blood glucose levels were assessed. RESULTS: Twelve subjects entered and completed the study. The mean total dexamethasone exposure (AUClast and AUCinf) following SP-102 by epidural injection was equivalent to the total exposure following IV USP. A lower mean plasma Cmax (~ 50% lower) was observed following epidural administration compared to IV injection. PD parameters were similar between treatments. Adverse events (AEs) were mild, with no serious AEs or study discontinuations due to AEs. CONCLUSION: In this small study, epidural SP-102 injection was well tolerated, was not associated with greater systemic dexamethasone exposure than IV USP, and both treatments had similar PD effects on cortisol suppression, blood glucose, and WBC levels.

Biorelevant In Vitro Skin Permeation Testing and In Vivo Pharmacokinetic Characterization of Lidocaine from a Nonaqueous Drug-in-Matrix Topical System.

Recently, lidocaine topical systems utilizing nonaqueous matrices have been developed and provide efficient lidocaine delivery through the skin, such that lower concentrations of drug provide equivalent or greater drug delivery than drug-in-matrix hydrogel lidocaine patches. This study characterizes drug delivery from a nonaqueous lidocaine topical system with increasing drug load both in vitro and in vivo. Topical systems formulated with either 1.8% or 5.4% lidocaine were applied to healthy volunteers' backs (n = 15) for 12 h in a single-center, open-label, four-treatment, four-period crossover pharmacokinetic study. Subjects were dosed with either three 1.8% systems or one, two, or three 5.4% systems in each period. Blood was collected for up to 48 h, and plasma lidocaine levels were measured with a validated HPLC method. In parallel, human and mouse skin models characterized the in vitro skin permeation profile. The pharmacokinetic profile was linear between one, two, and three lidocaine 5.4% applications. Application of three lidocaine 1.8% systems (108 mg lidocaine) was bioequivalent to one lidocaine 5.4% system (108 mg lidocaine). Both topical systems remained well adhered to the skin and irritation was mild. The 5.4% system had approximately threefold higher skin permeability than the 1.8% system in the mouse and human skin models. The results indicate increasing the drug load by three times results in triple the drug delivery both in vivo and in vitro. The relationship between the in vitro permeation and in vivo absorption correlates and is nonlinear.

Double-blind study of the actively transported levodopa prodrug XP21279 in Parkinson's disease.

The objective of this study was to assess the efficacy, safety, and pharmacokinetics of XP21279-carbidopa in patients with Parkinson's disease who experience motor fluctuations compared with immediate-release carbidopa-levodopa tablets. XP21279 is a levodopa prodrug that is actively absorbed by high-capacity nutrient transporters expressed throughout the gastrointestinal tract and then rapidly converted to levodopa by carboxylesterases. XP21279-carbidopa sustained-release bilayer tablets were developed to overcome pharmacokinetic limitations of levodopa by providing more continuous exposure. Patients with motor fluctuations who required carbidopa-levodopa four or five times daily were optimized for 2 weeks each on carbidopa-levodopa four or five times daily and XP21279-carbidopa three times daily in a randomized sequence. Next, they received each optimized treatment for 2 weeks in a double-blind/double-dummy, randomized sequence. The primary outcome measure was change from baseline in daily off time at the end of each double-blind treatment period. All patients at 2 sites underwent pharmacokinetic analyses. Twenty-eight of 35 enrolled patients completed both double-blind treatments. The mean total daily off time was reduced from baseline by a mean (± standard error) of 2.7 hours (± 0.48 hours) for immediate-release carbidopa-levodopa and 3.0 hours (± 0.57 hours) for XP21279-carbidopa (P = 0.49). Among 11 patients who completed pharmacokinetic sampling on each optimized treatment, the percentage deviation from the mean levodopa concentration was lower (P < 0.05) for XP21279-carbidopa than carbidopa-levodopa. Both treatments had a similar incidence of new or worsening dyskinesias. XP21279-carbidopa administered three times daily produced a reduction in off time similar to that of carbidopa-levodopa administered four or five times daily, and the difference was not statistically significant. XP21279-carbidopa significantly reduced variability in levodopa concentrations compared with carbidopa-levodopa.

A randomized, placebo-controlled trial of long-acting dexamethasone viscous gel delivered by transforaminal injection for lumbosacral radicular pain.

TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03372161.

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).

Open-Label Adhesion Performance Study of a Prescription Lidocaine Topical System 1.8% versus Three Lidocaine-Containing Over-the-Counter Patches in Healthy Subjects.

Purpose: This study evaluates and compares the clinical adhesion performance of a prescription lidocaine topical system 1.8% versus two different over-the-counter (OTC) lidocaine patches 4% and an OTC combination menthol and lidocaine patch 1%/4% in human subjects. Patients and Methods: This study was an open-label, randomized, four-treatment, four-sequence, Phase 1 adhesion performance study in healthy adult volunteers (N = 24). Lidocaine topical system 1.8% (R) and the three OTC patch products (T1, T2, and T3) were separately applied for 12 hours. Adhesion of all products was scored at 0, 3, 6, 8, and 12 hours post-application. Results: There were no issues with the conduct of the study. Overall, the majority (≥59.1%) of subjects treated ("patched") with the lidocaine topical system 1.8% (R) demonstrated ≥90% adhesion (FDA adhesion score 0) throughout the 12-hour administration period versus 27.3% of subjects treated with OTC lidocaine patch 4% (T1), 22.7% of subjects treated with OTC lidocaine patch 4% (T2), and 18.2% of subjects treated with OTC menthol/lidocaine patch 1%/4%. Only one subject (4.5%) treated with lidocaine topical system 1.8% was observed with <75% adhesion (FDA adhesion score <2) versus 11 (50.0%) and 10 (45.5%) for the two OTC lidocaine patches 4% (T1 and T2), respectively, and 13 (59.1%) subjects for the OTC menthol/lidocaine patch 1%/4%. There were no complete detachments observed for lidocaine topical system 1.8%, whereas 50.0% and 31.8% complete detachments were observed for the two OTC lidocaine patches 4% (T1 and T2), and 27.3% complete detachments were observed for the OTC menthol/lidocaine patch 1%/4%. No adverse events were observed for any of the treatments. Conclusion: Lidocaine topical system 1.8% demonstrated superior adhesion relative to the three lidocaine-containing OTC products over the 12-hour treatment period.

Benefit-risk assessment and reporting in clinical trials of chronic pain treatments: IMMPACT recommendations.

ABSTRACT: Chronic pain clinical trials have historically assessed benefit and risk outcomes separately. However, a growing body of research suggests that a composite metric that accounts for benefit and risk in relation to each other can provide valuable insights into the effects of different treatments. Researchers and regulators have developed a variety of benefit-risk composite metrics, although the extent to which these methods apply to randomized clinical trials (RCTs) of chronic pain has not been evaluated in the published literature. This article was motivated by an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting and is based on the expert opinion of those who attended. In addition, a review of the benefit-risk assessment tools used in published chronic pain RCTs or highlighted by key professional organizations (ie, Cochrane, European Medicines Agency, Outcome Measures in Rheumatology, and U.S. Food and Drug Administration) was completed. Overall, the review found that benefit-risk metrics are not commonly used in RCTs of chronic pain despite the availability of published methods. A primary recommendation is that composite metrics of benefit-risk should be combined at the level of the individual patient, when possible, in addition to the benefit-risk assessment at the treatment group level. Both levels of analysis (individual and group) can provide valuable insights into the relationship between benefits and risks associated with specific treatments across different patient subpopulations. The systematic assessment of benefit-risk in clinical trials has the potential to enhance the clinical meaningfulness of RCT results.

Safety of Epidural Steroid Injections for Lumbosacral Radicular Pain: Unmet Medical Need.

OBJECTIVE: Epidural steroid injections (ESIs) are a commonly utilized treatment for lumbosacral radicular pain caused by intervertebral disc herniation or stenosis. Although effective in certain patient populations, ESIs have been associated with serious complications, including paralysis and death. In 2014, the US Food and Drug Administration (FDA) issued a safety warning on the risk of injecting corticosteroids into the epidural space. The aims of this article were to review the neurological complications associated with ESIs and to compare the formulations, safety, and effectiveness of commercially available corticosteroids given by transforaminal, interlaminar, or caudal injection. METHODS: Serious adverse events associated with ESIs were identified by a search of the FDA Adverse Event Reporting System (FAERS) database. A MEDLINE search of the literature was conducted to identify clinical trials comparing the safety and effectiveness of nonparticulate and particulate corticosteroid formulations. RESULTS: Neurological complications with ESIs were rare and more often associated with the use of particulate corticosteroids administered by transforaminal injection. Among the 10 comparative-effectiveness studies reviewed, 7 found nonparticulate steroids had comparable efficacy to particulate steroids, and 3 studies suggested reduced efficacy or shorter duration of effect for nonparticulate steroids. DISCUSSION: The risk of complications for transforaminal ESI is greater with particulate corticosteroids. Nonparticulate corticosteroids, which are often recommended as first-line therapy, may have a short duration of effect, and many commercial formulations contain neurotoxic preservatives. The safety profile of ESIs may continue to improve with the development of safer, sterile formulations that reduce the risk of complications while maintaining efficacy.

Repeat Epidural Injections of SP-102 (Dexamethasone Sodium Phosphate Injectable Gel) in Subjects with Lumbosacral Radiculopathy.

PURPOSE: SP-102 is a novel epidural steroid injection (ESI) formulation of 10 mg dexamethasone sodium phosphate in a viscous gel solution. Repeat dosing of ESIs is possible if required for pain relief, but with consideration of hypothalamic-pituitary-adrenal (HPA) axis suppression from prolonged systemic exposure. This phase I/II study investigated the effect of initial and repeat SP-102 injections on HPA suppression and analgesia. METHODS: Subjects with lumbosacral radiculopathy received an initial epidural SP-102 injection (T1) on day 1, followed by a repeat injection (T2) on ≥28 days later. To determine HPA suppression, area under the effect curve over 28 days and maximum change from baseline were calculated for cortisol, glucose levels, and white blood cell (WBC) count. Equivalent effect on HPA suppression of T1 relative to T2 was determined if the 90% CIs for ratios of these measures were within 80%-125%. The effect of repeat injections on leg and back pain was also assessed. RESULTS: Based on the responder analysis, all subjects had achieved a cortisol response by day 3 after initial injection and by day 2 after repeat injection. The repeat injection had similar effects on glucose levels and WBC count to the initial injection. Pain scores decreased after each injection and remained low for the 28-day follow-up, with some evidence of improved analgesic effect of the second dose compared with the first. There were no serious adverse events or discontinuations due to adverse events. CONCLUSION: The lack of cumulative effect and rapid resolution of HPA suppression following repeated SP-102 dosing suggests that consideration of HPA pharmacodynamics is not clinically relevant when making decisions regarding repeat dosing. SP-102 ESIs provided prolonged pain relief, with preliminary evidence of greater efficacy after repeat injection. A phase III trial is ongoing. CLINICAL TRIAL IDENTIFIER: ClinicalTrials.gov: NCT03613662.

A Randomized, Crossover, Adhesion Performance and Pharmacokinetic Study of a Lidocaine Topical System Under Conditions of Water Exposure in Healthy Subjects.

PURPOSE: This study compares the adhesion performance, pharmacokinetic profile, and safety of lidocaine topical system 1.8%, which is approved to treat postherpetic neuralgia, under conditions of swimming and showering versus normal conditions. PATIENTS AND METHODS: This open-label, 3-period, 3-treatment crossover study randomized 24 healthy adults to receive one lidocaine topical system during each of three treatment periods; subjects either swam in a heated swimming pool for 15 minutes 4.0 hours post-product application (swimming), showered for 10 minutes 8.0 hours after product application (showering), or the product remained dry throughout the treatment period (normal conditions). The product was applied to the mid-upper back and was removed after 12 hours. The pharmacokinetic profile of each subject under water exposure conditions was compared to subjects under normal conditions. Skin irritation, adhesion, and adverse events were assessed. RESULTS: Twenty-four (24) subjects enrolled and 23 completed the study. Exposure to water resulted in lifting of the topical systems. There were two complete detachments, as well as seven occurrences of major lifting (more than 50% detached) after water exposure. The topical systems were immediately pressed down and/or reapplied after observing lifting and remained adhered to for the rest of the 12-hour application period. No clinically relevant differences in systemic absorption were observed under either showering or swimming conditions. The topical systems were well tolerated, with only mild adverse events, none leading to discontinuation. CONCLUSION: These data show that while water exposure can cause the topical system to lift or detach, the lidocaine topical system 1.8% is capable of being reapplied and maintains adhesion for up to 12 hours of wear with no clinically significant changes in drug delivery. CLINICALTRIALSGOV: NCT04784728.

Interpretation of chronic pain clinical trial outcomes: IMMPACT recommended considerations.

Interpreting randomized clinical trials (RCTs) is crucial to making decisions regarding the use of analgesic treatments in clinical practice. In this article, we report on an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) consensus meeting organized by the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks, the purpose of which was to recommend approaches that facilitate interpretation of analgesic RCTs. We review issues to consider when drawing conclusions from RCTs, as well as common methods for reporting RCT results and the limitations of each method. These issues include the type of trial, study design, statistical analysis methods, magnitude of the estimated beneficial and harmful effects and associated precision, availability of alternative treatments and their benefit-risk profile, clinical importance of the change from baseline both within and between groups, presentation of the outcome data, and the limitations of the approaches used.

Safety and efficacy of extended-release bupivacaine local anaesthetic in open hernia repair: a randomized controlled trial.

BACKGROUND: Pain relief remains a major problem in hernia surgery. SABER-Bupivacaine is an investigational extended-release formulation of bupivacaine in a resorbable matrix, which may provide up to 72 h of local pain relief. METHODS: A double-blinded, randomized controlled trial was undertaken to evaluate the safety and efficacy of SABER-Bupivacaine. Consented patients (n = 124) undergoing open inguinal hernia repair at five sites in Australia and New Zealand were randomized to receive either 2.5 (330 mg) or 5.0 mL (660 mg) of SABER-Bupivacaine or SABER-Placebo administered to the surgical wound at the end of the procedure. Analgesic efficacy and safety was evaluated. RESULTS: SABER-Bupivacaine appeared safe with no difference in the incidence of side effects compared with SABER-Placebo. The 5.0 mL dose of SABER-Bupivacaine reduced the mean area under the curve of pain intensity on movement compared with SABER-Placebo (2.47 versus 3.60; P = 0.0033) and decreased the number of patients requiring supplemental opioids by 26% (although not statistically significant; P = 0.0909). Normal wound healing was reported throughout the trial and at 3- and 6-month follow-up in every treatment group. CONCLUSION: After open inguinal hernia repair, SABER-Bupivacaine administered at the surgical site was safe and provided pain relief, reduced the need for supplemental (oral and parenteral) analgesia and did not impair wound healing.

Considerations for improving assay sensitivity in chronic pain clinical trials: IMMPACT recommendations.

A number of pharmacologic treatments examined in recent randomized clinical trials (RCTs) have failed to show statistically significant superiority to placebo in conditions in which their efficacy had previously been demonstrated. Assuming the validity of previous evidence of efficacy and the comparability of the patients and outcome measures in these studies, such results may be a consequence of limitations in the ability of these RCTs to demonstrate the benefits of efficacious analgesic treatments vs placebo ("assay sensitivity"). Efforts to improve the assay sensitivity of analgesic trials could reduce the rate of falsely negative trials of efficacious medications and improve the efficiency of analgesic drug development. Therefore, an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials consensus meeting was convened in which the assay sensitivity of chronic pain trials was reviewed and discussed. On the basis of this meeting and subsequent discussions, the authors recommend consideration of a number of patient, study design, study site, and outcome measurement factors that have the potential to affect the assay sensitivity of RCTs of chronic pain treatments. Increased attention to and research on methodological aspects of clinical trials and their relationships with assay sensitivity have the potential to provide the foundation for an evidence-based approach to the design of analgesic clinical trials and expedite the identification of analgesic treatments with improved efficacy and safety.