The challenge of developing pain medications for children: therapeutic needs and future perspectives

Evaluation of the effect of CYP2D6 and OCT1 polymorphisms on the pharmacokinetics of tramadol: Implications for clinical safety and dose rationale in paediatric chronic pain

AIMS

Our investigation aimed to assess the dose rationale of tramadol in paediatric patients considering the effect of CYP2D6/OCT1 polymorphisms on systemic exposure. Recommendations were made for the oral dose of tramadol to be used in a prospective study in children (3 months to < 18 years old) with chronic pain.

METHODS

Intravenous pharmacokinetic and genotype data from neonatal patients (n = 46) were available for this analysis. The time course of tramadol and O-desmethyltramadol (M1) concentrations was characterized using a nonlinear mixed effects approach in conjunction with extrapolation principles. Clinical trial simulations were then implemented to explore the effects of polymorphism, maturation and developmental growth on the disposition of tramadol and M1. Reported efficacious exposure range in adult subjects were used as reference.

RESULTS

The pharmacokinetics of tramadol and M1 was characterized by a two-compartment model. The total clearance of tramadol (CLPP) comprised CYP2D6-mediated metabolism (CLPM) and other pathways (CLPO). Age-related changes in CLPM, CLPO and M1 clearance (CLMO) were described by a sigmoid function, with CYP2D6 as a covariate on CLPP and CLPM,  and OCT1 on CLMO. Simulation scenarios including different CYP2D6/OCT1 combinations revealed that steady-state concentrations are above the putative ranges for analgesia in >15% and >70% of subjects after doses of 3 and 8 mg/kg, respectively.

CONCLUSIONS

In the absence of genotyping, reference exposure ranges can be used to define the dose rationale for tramadol in paediatric chronic pain. However, a starting dose of 0.5 mg/kg/day should be considered, followed by stepwise titration to the desired analgesic response.

Perceptions and experiences of community pharmacists with off-label prescribing in the pediatric population

OBJECTIVES

This study aimed to investigate and provide insight into the prevalence and patterns of off-label drug use in the pediatric population from the perspective of community pharmacists, addressing the existing data gap in a developing setting.

METHODS

A questionnaire-based cross-sectional study was conducted on Albanian community pharmacists in June 2021. The online administered survey explored the participants' demographic details, perceptions, and experiences with off-label prescriptions in pediatric patients. The statistical analysis conducted on the survey data comprised the construction of frequency tables and the application of the chi-square test for independence.

KEY FINDINGS

Three hundred and thirty-six community pharmacists nationwide completed the survey, out of which 186 (55.3%) were practiced in Tirana, the capital of Albania. Over 80% of surveyed pharmacists (n = 275) had encountered off-label drug prescriptions in pediatric patients, yet only 40% of participants reported dispensing medicines for off-label use. Community pharmacists reported that general pediatricians tended to prescribe off-label medications more frequently than pediatric subspecialists or general practitioners. It was found that off-label prescriptions were more frequently observed among children aged between 2 and 11 years. Antibiotics were the most reported medicines for off-label use in this study mentioned in almost all off-label categories.

CONCLUSIONS

Prescribing medicines for unapproved uses for the treatment of pediatric patients is present in community settings in Albania. This indicates the need for further data collection and analysis to understand off-label practices in our country's pediatric population comprehensively.

Rescue designs in analgesic trials from 0 to 2 years of age: scoping review

Pediatric analgesic trials are challenging, especially in newborns and infants. Following an FDA-academic consensus meeting, we analyzed pragmatic rescue designs in postoperative trials of local anesthetics, acetaminophen, opioids, and NSAIDs involving children ages 0-2 years and assessed surgical volumes to provide trial design recommendations. Searches of PubMed, Embase, CINAHL, The Cochrane Library, and Web of Science were conducted. A scoping approach identified trends in analgesic trials with an emphasis on randomized controlled trials (RCTs) utilizing immediate rescue designs. Age-specific surgical volumes were estimated from French national databases. Of 3563 studies identified, 23 RCTs used study medication(s) of interest and immediate rescue paradigms in children ages 0-2 years. A total of 270 studies met at least one of these criteria. Add-on and head-to-head designs were common and often used sparing of non-opioid or opioid rescue medication as a primary outcome measure. According to French national data, inguinal and penile surgeries were most frequent in ages 1 month to 2 years; abdominal and thoracic surgeries comprise approximately 75% of newborn surgeries. Analgesic trials with rescue sparing paradigm are currently sparse among children ages 0-2 years. Future trials could consider age-specific surgical procedures and use of add-on or head-to-head designs. IMPACT: Clinical trials of analgesic medications have been challenging in pediatrics, especially in the group from newborns to 2 years of age. Following an FDA-academic workshop, we analyzed features of completed analgesic trials in this age group. Studies using immediate rescue in placebo control, add-on, and head-to-head trial designs are pragmatic approaches that can provide important information regarding clinical effectiveness, side effects, and safety. Using a French national dataset with a granular profile of inpatient, outpatient, and short-stay surgeries, we provide information to future investigators on relative frequencies of different operations in neonates and through the first 2 years of life.

The Treatment of Pediatric Pain in Spain: A Survey Study

Pain is a common experience among children and adolescents, and pain management in this population is a challenge to clinicians. The aims of this study were to increase our understanding of current practices in the management of both acute and chronic pediatric pain in Spain, explore potential barriers to ideal practices, and identify professional needs as perceived by healthcare professionals. A total of 277 healthcare professionals took part, all of whom had wide experience in managing children and adolescents with pain (M [SD] age = 44.85, [10.73]; 75% women). Participants had to respond to a web-based survey with 50 questions related to pain education, organizational characteristics of their pain programs (including the characteristics of the patients treated), and current practices in the assessment and treatment of children and adolescents with pain. Almost all the participants (93%) acknowledged important gaps in their training, and only 47% reported that they had received specific education on the management of pediatric pain during their undergraduate and postgraduate studies. A third (31%) were members of multidisciplinary teams, and almost all (99%) understood that protocols to guide the management of pain in young people were necessary. However, only a few of them used a protocol to assess and treat (56% and 48%, respectively) acute and chronic pain (24% and 23%, respectively). The data also showed that a lack of pain education, coordination of professionals, and guidelines was perceived as an important barrier in the care provided to children and adolescents with pain in Spain. The findings of this study can now be used by healthcare professionals in Spain interested in managing pediatric pain, as well as policymakers concerned to improve the education of professionals and the care given to young people with pain.

Multiple Dose Pharmacokinetics of Tapentadol Oral Solution for the Treatment of Moderate to Severe Acute Pain in Children Aged 2 to

Background

Patients and Methods

Results

Conclusion

Comprehensive Pain Management Using Opioids for Children and Adolescents: Still a Wild Goose to Chase?

Children and adolescents treated for acute and chronic pain represent particular vulnerable patients with distinct and unmet medical and psychosocial needs that continue even beyond the complexity of treating the diseases they suffer [...]

Tapentadol for the Treatment of Moderate-to-Severe Acute Pain in Children Under the Age of Two Years

Background

Pharmacokinetics (PK), efficacy, and safety of the opioid analgesic tapentadol in the treatment of moderate-to-severe acute pain have so far not been investigated in pediatric patients <2 years of age.

Patients and Methods

Two multicenter, open-label trials assessed the pharmacokinetic profile, safety, tolerability, and efficacy of single doses of tapentadol oral solution (OS; NCT02221674; n=19) or intravenous infusion (IV, EudraCT 2014-002259-24; n=38) in children from birth to <2 years of age. Of these, 8 preterm neonates were included in the IV trial. A third randomized, double-blind, placebo-controlled trial (NCT02081391) investigated the efficacy and safety of multiple tapentadol OS doses in patients from birth to <2 years (placebo n=4, tapentadol n=11) using an immediate rescue trial design. Patients in all three trials underwent surgery that, in the investigator’s opinion, reliably produced moderate-to-severe pain requiring opioid treatment.

Results

Administration of single tapentadol doses resulted in tapentadol serum concentrations within the targeted range known to be safe and efficacious in adults and compared well to the range observed for children aged 2 to <18 years. Pain intensity already improved 15 min after administration. In the multiple dose trial, amounts of supplemental opioid analgesic medication within the first 24 h after start of trial medication were low (placebo 0.02 mg/kg, tapentadol 0.05 mg/kg). All patients stopped treatment with the trial medication because opioid analgesics were no longer required. Treatment-emergent adverse events occurred in 42.1% (tapentadol OS single dose), 28.9% (tapentadol IV), and 75% of placebo and 54.5% of tapentadol patients (tapentadol OS multiple doses), none of them serious.

Conclusion

Tapentadol showed a favorable PK and safety profile in children <2 years of age. Multiple tapentadol OS dosing is efficacious and generally well tolerated in children ≥2 years and might also be a useful treatment option for children <2 years in need of strong analgesics.

Outcomes of the Pediatric Development Plan of Tapentadol

The opioid analgesic tapentadol was the first pain medication to be developed for the treatment of pain in children under a formal process established by the regulatory authorities. This article summarizes the outcomes of the pediatric development program for tapentadol across the entire age range from birth (including neonates) to adolescents <18 years of age. In addition, the challenges experienced when designing and conducting the pediatric tapentadol clinical trials as well as the interactions with the regulatory authorities are discussed. As a first outcome, the oral solution of tapentadol was authorized in the EU in 2018 as a new treatment option in the hospital setting for moderate to severe acute pain in children from 2 to <18 years of age.

Pain Management in Childhood Leukemia: Diagnosis and Available Analgesic Treatments

Pain is one of the most common symptoms in children suffering from leukemia, who are often misdiagnosed with other childhood painful diseases such as juvenile idiopathic arthritis. Corticosteroid-induced osteonecrosis (ON) and vincristine-induced peripheral neuropathy (VIPN) are the most common painful manifestations. Additionally, ongoing pain may continue to impact quality of life in survivorship. This narrative review focuses on the pathophysiological mechanisms of pain in childhood leukemia and current available indications for analgesic treatments. Pain management in children is often inadequate because of difficulties in pain assessment, different indications across countries, and the lack of specific pediatric trials. Analgesic drugs are often prescribed off-label to children by extrapolating information from adult guidelines, with possible increased risk of adverse events. Optimal pain management should involve a multidisciplinary team to ensure assessment and interventions tailored to the individual patient.

Tapentadol Prolonged Release for Long-Term Treatment of Pain in Children

Purpose

Investigation of the efficacy and safety of tapentadol prolonged release (PR) compared with morphine PR for long-term treatment of pain in children.

Patients and Methods

Children aged 6 to <18 years requiring long-term treatment with opioids were studied in a 12-month, 2-part, multi-center trial: Part 1, 14-day open-label, randomized, active-controlled, parallel group non-inferiority trial comparing twice daily tapentadol PR with morphine PR; Part 2, open-label treatment with tapentadol PR for up to 12 months or no treatment “safety observation period”. Pain intensity was rated with visual analogue scale or Faces Pain Scale-Revised, and non-inferiority was assessed by comparison of “treatment responders” (those completing the 14-day treatment period and showing pre-defined changes in pain rating) in each group.

Results

Twenty-three of 48 centers enrolled 73 patients. In Part 1, 45 and 24 patients received tapentadol or morphine, respectively, of which 40 and 22 completed 14-day treatment. In Part 2, thirty-six and 58 patients entered the tapentadol PR or observation periods, respectively, with 20/36 completing at least 12 weeks of treatment; 10 of the 36 had received morphine in Part 1. Forty-four of the 58 patients in the safety observation period had received tapentadol. Tapentadol PR was non-inferior to morphine PR (lower limit of confidence interval above negative non-inferiority margin of −0.2) in Part 1. Rates of adverse events were as expected with nausea (22.2%) and constipation (15.6%) in the tapentadol PR group, and with vomiting (33.3%), nausea and constipation (each 16.7%) in the morphine PR group. No new safety issues were identified; the safety profile of tapentadol over the 12 months treatment and observation periods was comparable to that established in subjects >18 years old.

Conclusion

Tapentadol PR was well tolerated and equivalent to morphine PR for both efficacy and safety in children (6 to <18 years old) requiring long-term treatment with opioids.

Population Pharmacokinetics of Tapentadol in Children from Birth to <18 Years Old

OBJECTIVE

The main aim of this analysis was to characterize the pharmacokinetics (PK) of tapentadol in pediatric patients from birth to <18 years old who experience acute pain, requiring treatment with an opioid analgesic.

PATIENTS AND METHODS

Data from four clinical trials and 148 pediatric patients who received a single dose of tapentadol oral or intravenous solution were included. Population PK analysis was performed to determine the contribution of size-related (bodyweight) and function-related (maturation) factors to the changes in oral bioavailability (F), volume of distribution (V), and clearance (CL) with age. Simulations were carried out to compare pediatric exposures to reference adult values.

RESULTS

A one-compartment model with allometric scaling on disposition parameters (using theoretical or estimated exponents) and maturation functions on CL and F best described tapentadol PK. The estimated allometric exponents for CL (0.603) and V (0.820) differed slightly from the theoretical values of 0.75 for CL and 1 for V. A maximum in CL/F was observed at about 2-3 years when expressed on a bodyweight basis. Results for younger children as well as the F estimate were sensitive to the scaling approach, but CL/F and V/F as a function of age for the two scaling approaches led to similar curves within the bioequivalence range except below 5 weeks of age. Model-based simulations indicated that the doses used in the included clinical trials lead to exposures within the lower half of the targeted adult exposure.

CONCLUSION

The development of tapentadol is one of the first examples following a systematic approach for analgesic drug development for children. Our analysis enabled a full characterization and robust understanding of tapentadol PK in children from birth to <18 years, including preterm infants, and showed the importance of evaluating the sensitivity of the inferences of the PK parameters to the selected scaling approach.

Safe Use of Opioids in Chronic Kidney Disease and Hemodialysis Patients: Tips and Tricks for Non-Pain Specialists

In patients suffering from moderate-to-severe chronic kidney disease (CKD) or end-stage renal disease (ESRD), subjected to hemodialysis (HD), pain is very common, but often underestimated. Opioids are still the mainstay of severe chronic pain management; however, their prescription in CKD and HD patients is still significantly low and pain is often under-treated. Altered pharmacokinetics and the lack of clinical trials on the use of opioids in patients with renal impairment increase physicians' concerns in this specific population. This narrative review focused on the correct and safe use of opioids in patients with CKD and HD. Morphine and codeine are not recommended, because the accumulation of their metabolites may cause neurotoxic symptoms. Oxycodone and hydromorphone can be safely used, but adequate dosage adjustments are required in CKD. In dialyzed patients, these opioids should be considered as second-line agents and patients should be carefully monitored. According to different studies, buprenorphine and fentanyl could be considered first-line opioids in the management of pain in CKD; however, fentanyl is not appropriate in patients undergoing HD. Tapentadol does not need dosage adjustment in mild-to-moderate renal impairment conditions; however, no data are available on its use in ESRD. Opioid-related side effects may be exacerbated by common comorbidities in CKD patients. Opioid-induced constipation can be managed with peripherally-acting-μ-opioid-receptor-antagonists (PAMORA). Unlike the other PAMORA, naldemedine does not require any dose adjustment in CKD and HD patients. Accurate pain diagnosis, opioid titration and tailoring are mandatory to minimize the risks and to improve the outcome of the analgesic therapy.

Developments in combined analgesic regimens for improved safety in postoperative pain management

Introduction: Fixed-dose combination analgesic regimens may be similarly effective to opioid monotherapy but with potentially less risk. A number of individualized combination regimens can be created, including nonopioid agents such as acetaminophen and nonsteroidal anti-inflammatory drugs, opioids, and adjunctive agents such as gabapentin, pregabalin, and muscle relaxants. Areas covered: When such combinations have a synergistic effect, analgesic benefits may be enhanced. Many combination analgesic regimens are opioid sparing, which sometimes but not always results in reduced opioid-associated side effects. Safety concerns for all analgesics must be considered but postoperative analgesia is typically administered for a brief period (days), reducing risks that may occur with prolonged exposure. Expert opinion: Judiciously considered combination analgesic regimens can be effective postoperative analgesics that reduce opioid consumption without compromising pain control, which are important factors for patient recovery and satisfaction. The specific combinations used must be based on the patient, the type and duration of the surgical procedure, and complementary mechanisms of action of the agents used. In opioid-sparing combination analgesic regimens, the short-term use of small doses of opioids in this setting may be helpful for appropriate patients.

Pain management in children has significantly improved in the Italian emergency departments

AIM

Pain in children is often poorly assessed and treated in Italian emergency departments (EDs) as found in a survey conducted among the centres of the "Pain in Pediatric Emergency Room (PIPER)" Study Group in 2010. Our aim was to evaluate the changes in pain management in Italian EDs in the last years.

METHOD

A structured questionnaire about pain assessment, protocols, use of local anaesthetics before venipuncture, opioids and adjuvants was mailed to 46 Italian EDs between November 2017 and April 2018.

RESULTS

Pain was always assessed at triage in 34 centres (73.9%). Algometric scales were used in over 90% of EDs. Triage protocols were available in 37 centres (80.4%). Local anaesthetics before venipuncture were always used in six centres (13.0%). Protocols included opioids and adjuvants in 73.0% and 47.2%, respectively. Triage pain assessment was always done in 91.0% of the centres joining the PIPER Study Group up to 2015 and 56.5% in ones that joined the Group after 2015 (P = .017). Local anaesthetics before venipuncture were given in 39.1% of the centres joining until up to 2015 and 13.0% in ones that joined the Group after 2015 (P = .003).

CONCLUSION

Paediatric pain management has significantly improved in Italian EDs in the last 8 years. The centres joining the PIPER Study Group for longer time have shown better results for the indicators considered in the survey.

Efficacy and safety of multiple doses of tapentadol oral solution in the treatment of moderate to severe acute pain in children aged 2 to <18 years - a randomized, double-blind, placebo-controlled trial

Background

Well-controlled trials of analgesics in the pediatric population are scarce. Tapentadol is a strong centrally acting analgesic which has undergone a pediatric development program investigating its suitability for treating moderate to severe acute pain across the entire pediatric age range from birth to adolescence. Here, we report data from a pivotal Phase III trial performed as part of this development program.

Patients and methods

This randomized, double-blind, placebo-controlled, multicenter clinical trial investigated efficacy and safety/tolerability of multiple tapentadol oral solution doses (OS; target dose 1.25 mg/kg) in the treatment of postsurgical acute pain. Data for patients aged 2 to <18 years are reported here. The main objective of the trial was to investigate if oral tapentadol administration compared to placebo reduces the use of supplemental opioid analgesic medication within the first 24 hrs of treatment. Other investigated parameters included taste and palatability of the trial medication, adverse events (AEs), vital signs, and laboratory parameters.

Results

A total of 160 patients were included (placebo n=52, tapentadol n=108). It was shown that the total amount of supplemental opioid analgesic medication used in the first 24 hrs was significantly lower in tapentadol patients than placebo patients (p=0.0154). Taste and palatability of tapentadol OS was well perceived by most patients. Treatment-emergent AEs were reported in 50% of patients treated with placebo vs 57.4% in those exposed to tapentadol, most commonly vomiting, nausea, and constipation in both treatment groups.

Conclusion

Tapentadol OS was effective and generally well tolerated in children (≥2 years) for the treatment of moderate to severe acute pain. Across all age groups, palatability and acceptability of tapentadol OS were sufficient to ensure intake compliance. This trial provides evidence that tapentadol OS can be effectively used to treat pain in young patients for whom currently limited labelled treatment options are available.

Population pharmacokinetic modeling to facilitate dose selection of tapentadol in the pediatric population

OBJECTIVE

The main aim of this analysis was to characterize the pharmacokinetics (PK) of the strong analgesic tapentadol in 2-year-old to <18-year-old patients with acute pain and to inform the optimal dosing strategy for a confirmatory efficacy trial in this patient population.

METHODS

The analysis dataset included tapentadol concentrations obtained from 92 pediatric patients receiving a single tapentadol oral solution (OS) dose of 1.0 mg/kg bodyweight in two single-dose PK clinical trials. Population PK analysis was performed using nonlinear mixed effects modeling. Simulations were performed to identify tapentadol OS doses in pediatric subjects (2 to <18 years) that would produce exposures similar to those in adults receiving safe and efficacious doses of tapentadol IR (50-100 mg every 4 hrs).

RESULTS

Tapentadol PK in children aged from 2 to <18 years was best described by a one-compartment model. Mean population apparent clearance and apparent volume of distribution for a typical subject weighing 45 kg were 170 L/h and 685 L, respectively. Clearance, expressed in bodyweight units as L/h/kg, decreased with increasing age whereas total clearance (L/h) increased with increasing age. Model-based simulations suggested that a tapentadol OS dose of 1.25 mg/kg to children and adolescents aged 2 to <18 years would result in efficacious tapentadol exposures similar to those in adults receiving tapentadol immediate release 50-100 mg every 4 hrs. The proposed tapentadol OS dose was subsequently applied in a confirmatory efficacy trial in 2 to <18-year-old patients suffering from acute postsurgical pain.

CONCLUSION

This analysis provides an example of a model-based approach for a dose recommendation to be used in an efficacy trial in the pediatric population. Uniform dosing based on bodyweight was proposed for the treatment of acute pain in children aged from 2 to <18 years.

First evaluation of tapentadol oral solution for the treatment of moderate to severe acute pain in children aged 6 to <18

BACKGROUND

This is the first clinical trial in the global pediatric clinical development program for the use of the analgesic tapentadol in children and adolescents.

PATIENTS AND METHODS

This multicenter, open-label clinical trial investigated pharmacokinetics, safety and tolerability, and efficacy of tapentadol and its major metabolite tapentadol-O-glucuronide after administration of a single dose of tapentadol oral solution (OS) in pediatric patients aged 6 to <18 years experiencing moderate to severe acute pain after surgery. Efficacy (change in pain intensity after tapentadol intake) was assessed in an exploratory manner using the McGrath Color Analog Scale and Faces Pain Scale-Revised. Adverse events were monitored throughout the trial.

RESULTS

Forty-four patients who received a single dose of 1 mg/kg tapentadol OS were included in this investigation. Maximum serum concentrations of tapentadol (111 ng/mL) and tapentadol-O-glucuronide (2,400 ng/mL) observed in this trial were within the range of individual maximum concentrations observed in healthy adults administered a comparable dose (range for tapentadol 23.2-129 ng/mL, for tapentadol-O-glucuronide 1,040-4,070 ng/mL). Following tapentadol administration, pain intensity scores improved from baseline at all timepoints. Treatment-emergent adverse events, none of which were serious, were experienced by 45.5% of the patients; the most commonly reported were vomiting (29.5%) and nausea (9.1%).

CONCLUSIONS

Tapentadol OS administered as a single dose of 1 mg/kg in children aged 6 to <18 years was generally well tolerated and produced similar serum concentrations as administration of 50-100 mg tapentadol immediate-release tablets in adults. A decrease in postsurgical pain was observed using exploratory subject-reported pain assessments. Tapentadol OS may provide a new treatment option in the management of moderate to severe acute pain in children and adolescents.