Sebacoyl Dinalbuphine Ester Extended-release Injection for Long-acting Analgesia: A Multicenter, Randomized, Double-Blind, And Placebo-controlled Study in Hemorrhoidectomy Patients

Amphiphilic NLC-Gel formulation loaded with Sebacoyl dinalbuphine ester and Nalbuphine for localized postoperative pain management

Opioids are powerful analgesics; however, their significant systemic adverse effects and the need for frequent administration restrict their use. Nalbuphine (NA) is a κ-agonist narcotic with limited adverse effects, but needs to be frequently administrated due to its short elimination half-life. Whereas sebacoyl dinalbuphine ester (SDE) is a NA prodrug, which can effectively prolong the analgesic effect, but lacks immediate pain relief. Therefore, in this study, a rapid and sustained local delivery formulation to introduce NA and SDE directly into surgical sites was developed. An amphiphilic nanostructured lipid carrier (NLC) poloxamer 407 (P407) gel (NLC-Gel) was developed to permit concurrent delivery of hydrophobic SDE from the NLC core and hydrophilic NA from P407, offering a dual rapid and prolonged analgesic effect. Benefiting from the thermal-sensitive characteristic of P407, the formulation can be injected in liquid phase and instantly transit into gel at wound site. NLC-Gel properties, including particle size, drug release, rheology, and stability, were assessed. In vivo evaluation using a rat spinal surgery model highlighted the effect of the formulation through pain behavior test and hematology analysis. NLC-Gels demonstrated an analgesic effect comparable with that of commercial intramuscular injected SDE formulation (IM SDE), with only 15 % of the drug dosage. The inclusion of supplemental NA in the exterior gel (PA12-Gel + NA) provided rapid drug onset owing to swift NA dispersion, addressing acute pain within hours along with prolonged analgesic effects. Our findings suggest that this amphiphilic formulation significantly enhanced postoperative pain management in terms of safety and efficacy.

Breast Milk Excretion of Dinalbuphine Sebacate Injection Administered After Cesarean Section

Ensuring the safety of analgesics during lactation is crucial for women of childbearing potential. Available data regarding the transfer of nalbuphine for postoperative acute pain via breast milk are limited to the postmarketing experience. This lactation study aimed to assess nalbuphine and dinalbuphine sebacate concentrations in breast milk from lactating women with postoperative pain treated with dinalbuphine sebacate extended-release injection (150 mg dinalbuphine sebacate/2 mL Naldebain). Breast milk was collected throughout the 5-day posthospitalization interval from 20 mothers injected with one dose of extended-release dinalbuphine sebacate intramuscularly. Maternal safety was assessed during the study period. Nalbuphine was detectable in 71% of milk samples collected from all mothers, whereas dinalbuphine sebacate was undetectable or below the quantitation limit (0.1 ng/mL). The mean nalbuphine concentration in milk was approximately 10.55 ng/mL, with the peak concentration reaching up to 12.7 ng/mL. The mean relative infant dose was 0.39% (coefficient of variation, 65%). The mean pain intensity at rest was reduced to mild pain from Day 2 morning to discharge. Overall, the maternal safety profile was tolerable. The breast milk of women who receive one dose of dinalbuphine sebacate injection postpartum contains low nalbuphine concentration. In addition, dinalbuphine sebacate injection potentially reduces maternal pain intensity during the first postpartum week and offers low toxicity risk among breastfed infants.

Novel Opioids in the Setting of Acute Postoperative Pain: A Narrative Review

Although traditional opioids such as morphine and oxycodone are commonly used in the management of acute postoperative pain, novel opioids may play a role as alternatives that provide potent pain relief while minimizing adverse effects. In this review, we discuss the mechanisms of action, findings from preclinical studies and clinical trials, and potential advantages of several novel opioids. The more established include oliceridine (biased ligand activity to activate analgesia and downregulate opioid-related adverse events), tapentadol (mu-opioid agonist and norepinephrine reuptake inhibitor), and cebranopadol (mu-opioid agonist with nociceptin opioid peptide activity)-all of which have demonstrated success in the clinical setting when compared to traditional opioids. On the other hand, dinalbuphine sebacate (DNS; semi-synthetic mu partial antagonist and kappa agonist), dual enkephalinase inhibitors (STR-324, PL37, and PL265), and endomorphin-1 analog (CYT-1010) have shown good efficacy in preclinical studies with future plans for clinical trials. Rather than relying solely on mu-opioid receptor agonism to relieve pain and risk opioid-related adverse events (ORAEs), novel opioids make use of alternative mechanisms of action to treat pain while maintaining a safer side-effect profile, such as lower incidence of nausea, vomiting, sedation, and respiratory depression as well as reduced abuse potential.

IUPHAR Review - Bivalent and bifunctional opioid receptor ligands as novel analgesics

Though efficacious in managing chronic, severe pain, opioid analgesics are accompanied by significant adverse effects including constipation, tolerance, dependence, and respiratory depression. The life-threatening risks associated with µ opioid receptor agonist-based analgesics challenges their use in clinic. A rational approach to combatting these adverse effects is to develop agents that incorporate activity at a second pharmacologic target in addition to µ opioid receptor activation. The promise of such bivalent or bifunctional ligands is the development of an analgesic with an improved side effect profile. In this review, we highlight ongoing efforts in the development of bivalent and bifunctional analgesics that combine µ agonism with efficacy at κ and δ opioid receptors, the nociceptin opioid peptide (NOP) receptor, σ receptors, and cannabinoid receptors. Several examples of bifunctional analgesics in preclinical and clinical development are highlighted, as are strategies being employed toward the rational design of novel agents.

Efficacy and safety of an extended-release sebacoyl dinalbuphine ester for laparoscopic cholecystectomy: A randomized controlled trial

BACKGROUND

A long-acting κreceptor agonist parenteral analgesic may theoretically improve acute pain and reduce incidence of chronic postsurgical pain (CPSP) after laparoscopic cholecystectomy with minimal drug-related side effects of the traditional μreceptor opioids.

METHODS

Eighty adult patients undergoing elective laparoscopic cholecystectomy were randomly assigned to receive single intramuscular injection of an extended-release sebacoyl dinalbuphine ester (SDE, Naldebain 150 mg; n = 40) or placebo (n = 40) after anesthesia induction. Standard multimodal analgesia (MMA) was administered for postoperative pain control. The primary endpoint was pain intensity within 7 days after surgery. The secondary endpoints were incidence CPSP at 3 months and adverse reactions up to 7 days after surgery.

RESULTS

The highest visual analogue scale (VAS) and area under the curve of VAS 0 to 48 hours after operation were not different between the two groups and a similar proportion of patients requested rescue parenteral analgesics. Average pain intensities were also not different at 72 hours and 7 days after surgery. Incidence of CPSP was 22.5% and 13.1% in patients who received placebo and SDE treatment, respectively (P = .379). Significantly higher incidence of drug-related adverse events, including dizziness, nausea and injection site reactions, were recorded in the SDE group.

CONCLUSION

A single dose of extended-release analgesic SDE given intraoperatively did not provide sufficient add-on effect for acute and chronic pain management after laparoscopic cholecystectomies in patients who received standard postoperative MMA. Intramuscular injection of 150 mg SDE in patients with average body mass causes adverse events that could have been overlooked. More clinical studies are warranted to determine the target populations who may benefit from SDE injections for improvement of acute and chronic postsurgical pain management.

Efficacy and Safety of Parenteral Injection of an Extended Release κ-receptor Opioid Sebacoyl Dinalbuphine Ester for Acute and Chronic Pain After Laparoscopic Bariatric Surgery: a Randomized, Placebo-Controlled, Double-Blind Trial

PURPOSE

μ-receptor opioids are associated with unwanted gastrointestinal side effects and respiratory depression. A long-acting non-μ-receptor parenteral opioid is not currently available for management of acute and chronic postsurgical pain (CPSP). This double-blind clinical trial tested an extended-release κ-receptor agonist, sebacoyl dinalbuphine ester (SDE, Naldebain®) for management of surgical pain after laparoscopic bariatric surgery.

MATERIALS AND METHODS

Patients were randomly assigned to receive a single intramuscular injection of SDE (150 mg, n = 30) or vehicle solution (n = 30) at > 12 h before surgery. All patients received standard perioperative multimodal analgesia (MMA). The primary endpoint was the pain intensity in the beginning 7 days after operation. The secondary endpoints were adverse reactions up to 7 days and incidence of CPSP at 3 months after surgery.

RESULTS

Compared with placebos, the area under curves of visual analog scale (VAS) for 0-48 h after operation were significantly reduced in SDE group (143.3 ± 65.4 and 105.9 ± 36.3, P = 0.025). There were significantly fewer patients in the SDE group who had moderate-to-severe pain (VAS ≥ 4) (16.7% vs 50%; P = 0.012) at postoperative 48 h. Pain intensities were similar between the two groups at 72 h and 7 days postoperatively. The incidence of CPSP at 3 months was not different. SDE did not increase drug-related systemic adverse events.

CONCLUSION

In addition to the standard perioperative MMA, a single-dose injection of long-acting κ-receptor agonist SDE provides significantly better pain management for 48 h following laparoscopic bariatric surgery. A long-acting κ-receptor agonist opioid could improve in-hospital pain management and potentiate early discharge after operation without increasing drug-related systemic complications.

Repurposing of parenterally administered active substances used to treat pain both systemically and locally

Pain is a constant in our lives. The efficacy of drug therapy administered by the parenteral route is often limited either by the physicochemical characteristics of the drug itself or its adsorption-distribution-metabolism-excretion (ADME) mechanisms. One promising alternative is the design of innovative drug delivery systems that can improve the pharmacokinetics |(PK) and/or reduce the toxicity of traditionally used drugs. In this review, we discuss several products that have been approved by the main regulatory agencies (i.e., nano- and microsystems, implants, and oil-based solutions), highlighting the newest technologies that govern both locally and systemically the delivery of drugs. Finally, we also discuss the risk assessment of the scale-up process required, given the impact that this approach could have on drug manufacturing. Teaser: The management of pain by way of the parenteral route can be improved using complex drug delivery systems (e.g., micro- and nanosystems) which require high-level assessment and shorten the regulatory pathway.

Multimodal Analgesia with Extended-Release Dinalbuphine Sebacate for Perioperative Pain Management in Upper Extremity Trauma Surgery: A Retrospective Comparative Study

Introduction

Patients undergoing upper extremity fracture surgery (UEFS) commonly suffer from unbearable acute pain. Opioids remain the mainstay of moderate to severe pain alleviation, although there is a growing concern regarding the increasing trend in misuse and abuse. This study aimed to observe the safety and efficacy of dinalbuphine sebacate (DS), a novel extended-release analgesic, along with multimodal analgesia (MMA) for post-UEFS pain control.

Methods

We retrospectively reviewed the records of patients undergoing UEFS between August 2020 and January 2021. Eligible patients were included and divided into two groups, depending on the analgesic regimen. In the DS group, 150 mg DS was administered intramuscularly at least 12 h pre-operatively, while in the conventional analgesia (CA) group, 40 mg parecoxib was given within 3 h before surgery. Intraoperative fentanyl administration was guided by the Analgesia Nociception Index System in both groups. For breakthrough pain, fentanyl was used as rescue medicine in the postanaesthesia care unit while tramadol and parecoxib were administered in the ward.

Results

Forty-nine patients were allocated to the DS group and 60 patients were allocated to the CA group. In comparison with the CA group, the proportion of patients requiring opioids for breakthrough pain post-operatively was significantly lower in the DS group (fentanyl: 31% vs. 68%, p < 0.001; tramadol: 27% vs. 70%, p < 0.001). The DS group also consumed lower amounts of post-operative rescue opioids. Furthermore, both mean worst and least pain scores were significantly lower in the DS group from post-operative day (POD) 1 to POD 5. There was no significant difference in intraoperative consumption of fentanyl or incidence of adverse events.

Conclusion

This result suggests that extended-release DS is a suitable analgesic incorporated in MMA and a promising solution to the misuse and abuse of opioids.

Postoperative pain: a review of emerging therapeutic options

INTRODUCTION

Postoperative pain is often managed by opioid medications, even though they carry a risk of adverse effects such as vomiting, constipation, sedation, respiratory depression and physical dependence. Furthermore, opioid use in the healthcare setting has likely contributed to the epidemic. However, the mismanagement of postoperative pain can result in delayed recovery time, impaired physical function, increased risk of morbidity and mortality, chronic pain, and higher healthcare costs.

AREAS COVERED

This review explores emerging therapeutic options and strategies in the management of acute postoperative pain and focuses on opioid-sparing, multimodal analgesia. This includes regional anesthetic techniques, non opioid pharmacotherapy, novel opioids and non-pharmacologic therapy. We have also discussed examples of novel analgesics and formulations which have potential benefits in reducing postoperative pain and opioid use after surgery.

EXPERT OPINION

The development of novel regional anesthesia techniques allows for opioid minimization in increasing number of surgical procedures. This synergizes with the availability of novel non-opioid analgesic adjucts. In addition, several novel opioid drugs have been developed which may be pathway selective and associated with less adverse effect than conventional opioids.

Comparison of the Efficacy and Safety of Dinalbuphine Sebacate, Patient-Controlled Analgesia, and Conventional Analgesia After Laparotomy for Gynecologic Cancers: A Retrospective Study

Objective

We aimed to investigate the effects of dinalbuphine sebacate (DNS), fentanyl-based patient-controlled analgesia (PCA), and conventional analgesia (CA) for pain management after laparotomy for gynecologic cancers.

Methods

A total of 137 eligible patients who underwent laparotomy through a midline incision wound for gynecologic cancer between July 2019 and June 2020 were retrospectively evaluated. The patients were divided into three groups as follows: the intramuscular DNS, intravenous PCA, and CA groups. Postoperative pain (POP) intensity as measured with a numerical rating scale (NRS), total consumption of analgesics, and incidence of treatment-emergent adverse events were compared between the three groups.

Results

The DNS group showed significant reduction in NRS pain intensity than the PCA and CA groups on day 1 (4.8 vs 6.2, p < 0.01 and 6.2, p < 0.05, respectively), day 2 (3.0 vs 4.7, p < 0.01 and 4.8, p < 0.001, respectively), day 3 (2.0 vs 3.9, p < 0.001 and 3.5, p < 0.001, respectively), day 4 (1.1 vs 3.1, p < 0.001 and 2.9, p < 0.001, respectively), and day 5 (0.7 vs 2.3, p < 0.001 and 2.4, p < 0.001, respectively). The total consumption of morphine equivalents per day was similar between the DNS and PCA groups (142.8 ± 7.3 mg vs 137.7 ± 70.0 mg, p = 0.8032) and lowest in the CA group (11.7 ± 30.7 mg, p < 0.0001). The overall safety profile was comparable between the DNS, PCA, and CA groups. The patients in the DNS group complained less of dizziness postoperatively than those in the PCA group (27% vs 47%) and had less nausea than those in the CA group (13% vs 33%).

Conclusion

A single DNS injection was more effective for relieving POP than PCA and CA in the patients who had a longitudinal incision for gynecologic cancer surgery. DNS was well tolerated and had less adverse effects than PCA and CA.

Multimodal Analgesia With Long-Acting Dinalbuphine Sebacate Plus Transversus Abdominis Plane Block for Perioperative Pain Management in Bariatric Surgery: A Case Report

Laparoscopic bariatric surgery is increasingly performed in morbidly obese patients. However, post-surgical pain is common and is usually managed with classical opioids such as morphine and fentanyl. Further, morbidly obese patients are predisposed to opioid-related side effects, especially post-operative nausea and vomiting (PONV), and respiratory depression. Obstructive sleep apnea in morbidly obese patients even predisposes them to respiratory depression. Thus, reducing opioid consumption is important. Multimodal analgesia (MMA) provides optimal perioperative analgesia while minimizing opioid consumption. Studies have shown that MMA strategy can provide sufficient pain relief in bariatric surgery with enhanced recovery. There are very few reports on the use of dinalbuphine sebacate (DS), a newly introduced non-controlled opioid medication with long-lasting analgesic effects. DS has a different mechanism of action from that of morphine or fentanyl and is non-addictive, with minimal side effects. It has been successfully used in laparoscopic cholecystectomy in our previous study. We present a case of a new MMA protocol with DS on a 46-year-old morbidly obese female patient who underwent laparoscopic sleeve gastrectomy. The MMA protocol included ultrasound-guided intramuscular DS injection plus transversus abdominis plane (TAP) block and other analgesics; it achieved good perioperative analgesia with opioid-sparing effect and enhanced patient's recovery with no pain in the following 4 months.

Evidence-based review of methods used to reduce pain after excisional hemorrhoidectomy

Background Excisional hemorrhoidectomy is one of the most commonly performed anorectal procedures. Despite the satisfactory outcomes of excisional hemorrhoidectomy, the pain perceived by the patients following the procedure can be a distressing sequel. This review aimed to search the current literature for the existing evidence on how to avoid or minimize the severity of post-hemorrhoidectomy pain.

Methods An organized literature search was performed using electronic databases including PubMed/Medline and Google Scholar service for the articles that evaluated different methods for pain relief after excisional hemorrhoidectomy. Then, the studies were summarized in a narrative way illustrating the hypothesis and the outcomes of each study. The methods devised to reduce pain after excisional hemorrhoidectomy were classified into three main categories: technical tips; systemic and topical agents; and surgical methods. The efficacy of each method was highlighted along the level of evidence supporting it.

Results Stronger evidence (level Ia) supported LigaSure hemorrhoidectomy and the use of glyceryl trinitrate ointment to be associated with significant pain relief after excisional hemorrhoidectomy whereas the remaining methods were supported by lower level of evidence (level Ib).

Conclusion The use of LigaSure in performing excisional hemorrhoidectomy and the application of topical glyceryl trinitrate ointment contributed to remarkable relief of postoperative pain after excisional hemorrhoidectomy according to the highest level of evidence. Perhaps a multimodality strategy that combines systemic and topical agents can be the optimal method for control of pain after excisional hemorrhoidectomy, yet further prospective trials are required to draw such conclusion.

The Effect of Perianal Tramadol Infiltration on Postoperative Pain Following Hemorrhoidectomy

INTRODUCTION

The present study was attempted to evaluate the effect of perianal infiltration of tramadol on postoperative pain in patients undergoing hemorrhoidectomy.

METHOD

This double-blind clinical trial study was carried out on 90 patients with grade 3 and 4 hemorrhoids undergoing hemorrhoidectomy. Patients were randomly assigned into 3 groups of control or bupivacaine or tramadol. Before the surgery, perianal infiltration of .25% bupivacaine or tramadol or normal saline was prescribed to each group, respectively. Data on pain severity (based on the visual analog scale (VAS), the duration of surgery, sedation score, pain at the first defecation, first request time for additional analgesia, nausea and vomiting, and analgesic intakes) were evaluated and analyzed.

RESULTS

Duration of surgery was almost similar in all 3 groups (P = .974). The results showed a significant difference in pain score between 3 groups (P ≤.05) at all times after the surgery. In addition, the means of sedation scores (P = .03), pain score at the first defecation (P = .001), the time to first analgesic request (P = .001), and ketorolac administration times (P = .01) were significantly different between 3 groups. Finally, no complication was reported regarding postoperative nausea and vomiting.

CONCLUSION

Given the notable efficacy of tramadol in reducing pain after hemorrhoidectomy and its minor side effects, this medication is suggested as an effective topical anesthetic to decrease pain after hemorrhoidectomy.

Clinically established biodegradable long acting injectables: An industry perspective

Long acting injectable formulations have been developed to sustain the action of drugs in the body over desired periods of time. These delivery platforms have been utilized for both systemic and local drug delivery applications. This review gives an overview of long acting injectable systems that are currently in clinical use. These products are categorized in three different groups: biodegradable polymeric systems, including microparticles and implants; micro and nanocrystal suspensions and oil-based formulations. Furthermore, the applications of these drug delivery platforms for the management of various chronic diseases are summarized. Finally, this review addresses industrial challenges regarding the development of long acting injectable formulations.

Extended-Release Dinalbuphine Sebacate Versus Intravenous Patient-Controlled Analgesia with Fentanyl for Postoperative Moderate-to-Severe Pain: A Randomized Controlled Trial

INTRODUCTION

Post-operative pain control remains unsatisfactory in patients after laparotomy. This study aimed to evaluate the efficacy, safety, and quality of life with a single dose of extended-release dinalbuphine sebacate (ERDS) pre-operatively to intravenous patient-controlled analgesia (PCA) with fentanyl in patients undergoing laparotomy.

METHODS

This was a prospective, open-label, randomized controlled study. Of 110 randomized patients, 107 completed all assessments. The area under the curve (AUC) of visual analogue scale (VAS) from baseline to 48 h after surgery, VAS throughout 7 days after surgery, post-operative analgesics use, quality of life, satisfaction, and safety were evaluated.

RESULTS

The AUC of VAS from baseline to 48 h after surgery were 118.6 [97.5% confidence interval (CI) 95.6-141.6] in ERDS group and 176.13 (97.5% CI 150.8-201.4) in PCA group, which showed the non-inferiority because the upper limit of the 97.5% CIs of ERDS group was lower than the lower limit of PCA group (P < 0.001), but also had superiority in favor of ERDS group (P < 0.001). ERDS group reported a significant reduction in VAS pain intensity at 4, 24, 32, 72, 120, and 144 h after surgery, and better quality of life (P < 0.05). The safety profile was comparable between ERDS and PCA groups.

CONCLUSIONS

In patients undergoing laparotomy, a single dose of dinalbuphine sebacate was superior to intravenous PCA with fentanyl on lower pain intensity and better quality of life.

TRIAL REGISTRATION

NCT03296488.

Preoperative Administration of Extended-Release Dinalbuphine Sebacate Compares with Morphine for Post-Laparoscopic Cholecystectomy Pain Management: A Randomized Study

Purpose

Perioperative pain management plays a critical role in the effort to promote enhanced recovery after surgery (ERAS). Pain is also the most concern for patients after laparoscopic cholecystectomy (LC). Naldebain (extended-release dinalbuphine sebacate, DS) is an oil-based formulation for intramuscular injection that has been designed for extended release and can be used for preoperative analgesia over a 7-day period. This study was aimed to compare the efficacy of DS injection with that of regular postoperative morphine administered when necessary for the management of post-laparoscopic cholecystectomy pain.

Patients and Methods

Forty-four patients scheduled for elective laparoscopic cholecystectomy were included in this prospective study. The patients were allocated randomly into two groups, with equal numbers receiving preoperative DS versus post-operative morphine. A total of 21 and 22 patients completed the study within the preoperative DS and post-operative morphine group, respectively.

Results

There were no statistically significant differences between two treatment groups with respect to length of surgery, anesthetics used during operation, or the average visual analog scale pain score in the post-operative anesthesia care unit (PACU), and at 4, 24, 48, and 72 hours post-procedure. Morphine was required only during the first postoperative day among those in the DS group. Safety was comparable in both DS and morphine groups.

Conclusion

A single preoperative dose of DS provides sufficient analgesia along with a manageable safety profile and no interference with surgical anesthetics when compared to control cases that underwent surgery without preoperative DS treatment. This pilot study suggests that preoperative administration of DS is safe and may decrease the need for postoperative opioid use after laparoscopic cholecystectomy.

Registration

ClinicalTrials.gov Identifier: NCT03713216.

Comparing efficacy and safety between Naldebain® and intravenous patient-controlled analgesia with fentanyl for pain management post-laparotomy: study protocol for a randomized controlled, non-inferior trial

Background

A long-acting prodrug of nalbuphine, nalbuphine sebacate, has been developed for meeting the unmet medical need of long-acting analgesics. Naldebain^® (nalbuphine sebacate) has been developed as a new premedication for postoperative pain management. The primary objective of this study is to determine the efficacy and safety of a single dose of intramuscular Naldebain^® in patients scheduled to undergo elective laparotomy.

Methods/design

A total of 110 patients will be recruited and randomized into two treatment groups. Group 1 receives a single dose of Naldebain^® intramuscularly 24 ± 12 h prior to surgery. Group 2 receives intravenous patient-controlled analgesia (PCA) with fentanyl through 48 h postsurgery. Both groups will have follow-up observations until the final visit (day of discharge, day 6–30). The primary efficacy endpoint is to assess time-specific pain intensity calculated as the area under the curve (AUC) of a visual analog scale at individual time points and by using total AUC. Safety endpoints—including incidence of treatment, emergent adverse events, and percentage of abnormality from baseline to final visit—in vital signs, laboratory tests, and injection site evaluations will also be analyzed. Statistical analyses will be performed on the data to compare the two groups.

Discussion

Post-laparotomy pain can have a harmful effect on patient recovery; therefore, a slow-release formulation that can cover at least 7 days of analgesic effect is required. This study will demonstrate whether a single use of Naldebain^® is not less efficacious than PCA with fentanyl for pain management as a non-inferior trial.

Trial registration

NCT03296488.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3260-4) contains supplementary material, which is available to authorized users.