Review of extended-release formulations of Tramadol for the management of chronic non-cancer pain: focus on marketed formulations

Development, Physicochemical Characteristics and Pharmacokinetics of a New Sustained-Release Bilayer Tablet Formulation of Tramadol with an Immediate-Release Component for Twice-Daily Administration

BACKGROUND AND OBJECTIVE

There are some potential concerns about the currently marketed solid oral dosage forms of tramadol, including decreased adherence to immediate-release (IR) formulations due to the high number of doses taken each day and the slow rise in the blood tramadol concentration after administration of sustained-release (SR) formulations, which may not achieve a rapid analgesic effect. To overcome these potential concerns, a twice-daily double-layered tablet formulation of tramadol comprising IR and SR layers was developed. This article reports studies that assessed its physicochemical and pharmacokinetic properties.

METHODS

Dissolution tests of five bilayer tablet formulations (designated tablets A-E) and pharmacokinetic studies of tablets A and B were conducted to investigate the appropriate ratio of the IR/SR layers in the double-layered tablet. Additionally, pharmacokinetic studies of three finished dosage formulations (tablets C-E) were performed in healthy adult males to investigate the effect of food intake on drug absorption.

RESULTS

Adjusting the excipients and tramadol content in the IR and SR layers of tablets A-E altered their dissolution profiles in a manner that could be predicted based on their compositions. The IR layer was released within 15 min, and the SR layer was slowly released over 10 h. In the pharmacokinetic study, the time to maximum plasma concentration (tmax) of tramadol after administration of tablets A (IR:SR: 20:80 mg) and B (40:60 mg) was shorter than that of a commercially available SR tablet, and the half-life (t1/2) was longer than that of a commercially available IR tablet. For tablets C-E, administration after food did not affect the area under the concentration-time curve (AUC) or maximum drug concentration (Cmax) of tramadol, but the tmax was prolonged by about 1 h compared with administration in fasting conditions. The mean ± standard deviation tmax and t1/2 for tablet D (IR:SR: 35:65 mg) in the fasting condition was 1.09 ± 0.56 h and 7.82 ± 0.85 h, respectively. The respective values in the fed condition were 2.47 ± 1.06 h and 7.12 ± 0.85 h, respectively.

CONCLUSIONS

To address the potential concerns regarding existing formulations of tramadol, a twice-daily, extended-release bilayer formulation of tramadol consisting of an IR and SR layer was developed. Pharmacokinetic studies confirmed that the plasma tramadol concentration increased quickly after administration and was maintained over a long period of time.

Efficacy and safety of twice-daily tramadol hydrochloride bilayer sustained-release tablets with an immediate release component for postherpetic neuralgia: Results of a Phase III, randomized, double-blind, placebo-controlled, treatment-withdrawal study

BACKGROUND

We investigated the efficacy and safety of twice-daily bilayer sustained-release tramadol hydrochloride tablets (35% immediate-release; 65% sustained-release) in patients with postherpetic neuralgia.

METHODS

This was a Phase III treatment-withdrawal study with 1-4-week dose-escalation, 1-week fixed-dose, and 4-week randomized, double-blind, placebo-controlled withdrawal periods performed at 43 medical institutions in Japan. Patients aged ≥20 years, ≥3 months after the onset of herpes zoster with localized, persistent pain despite fixed-dose analgesics for ≥2 weeks before enrollment were eligible. Patients started tramadol at 100 mg/day and its dose escalated to a maximum of 400 mg/day to achieve a reduction in their Numeric Rating Scale (NRS) for pain of ≥2 points. Eligible patients were randomized to continue tramadol or switched to placebo for 4 weeks (double-blind period). Patients were withdrawn due to inadequate analgesia (NRS deteriorated on ≥2 consecutive days) or their request.

RESULTS

Overall, 252 patients started tramadol and 173 were randomized (tramadol: 85; placebo: 88). Tramadol was superior to placebo for the primary endpoint (time from randomization to an inadequate analgesic effect) with log-rank test p = 0.0005. The hazard ratio was 0.353 (95% confidence interval 0.190-0.657) in favor of tramadol and fewer patients in the tramadol group experienced inadequate analgesic effects (16.9% vs. 39.8%). Adverse events in ≥10% of patients in the open-label period were constipation (43.8%), nausea (34.9%), somnolence (18.5%), and dizziness (11.6%). The frequencies of adverse events in the double-blind period were similar in both groups.

CONCLUSION

Sustained-release tramadol tablets with an immediate-release component are effective and well tolerated for managing postherpetic neuralgia.

Efficacy and Safety of Tramadol Hydrochloride Twice-Daily Sustained-Release Bilayer Tablets with an Immediate-Release Component for Chronic Pain Associated with Knee Osteoarthritis: A Randomized, Double-Blind, Placebo-Controlled, Treatment-Withdrawal Study

Background and Objectives

Knee osteoarthritis pain is a chronic form of pain for which conventional non-steroidal anti-inflammatory drugs may provide insufficient analgesia. Twice-daily tramadol hydrochloride (65% sustained-release/35% immediate-release) bilayer tablets are a novel formulation of tramadol developed for managing chronic pain. The objectives of this study were to examine the effectiveness and safety of this formulation in patients with chronic knee osteoarthritis pain.

Methods

This was a multicenter, randomized, placebo-controlled, double-blind, parallel-group, treatment-withdrawal study. Patients with a reduction in Numeric Rating Scale (NRS) for pain of ≥2 points during a 1–3-week, open-label, tramadol dose-escalation period (100–300 mg/day) were randomized to continue tramadol or switched to placebo for 4 weeks (double-blind period). Patients with inadequate efficacy (increase in NRS ≥2 points/patient request) were withdrawn. Outcomes included the time to inadequate analgesic efficacy from randomization (primary endpoint), the cumulative retention rate, and safety.

Results

Overall, 249 and 160 patients entered the dose-escalation and double-blind periods, respectively (tramadol 79; placebo 81). Kaplan–Meier analysis revealed superiority of tramadol (log-rank p = 0.042), and a hazard ratio of 0.50 (95% confidence interval [CI] 0.25–0.99). Documentation of an inadequate analgesic effect was less frequent in the tramadol group (15.4%, 95% CI 8.2–25.3% vs. 30.9%, 95% CI 21.1–42.1%). The cumulative retention rate was greater in the tramadol group (83.7% vs. 69.0%). Adverse events occurred in 80.6% (200/248) of patients in the open-label period, and in 38.5% (30/78) and 13.6% (11/81) of patients in the tramadol and placebo groups, respectively, in the double-blind period. Opioid-associated adverse events, such as nausea, vomiting, constipation, somnolence, and dizziness, were the most frequent events.

Conclusion

This study demonstrated the analgesic efficacy and safety of sustained-release tramadol tablets with an immediate-release component for chronic knee osteoarthritis pain.

Trial registration

JapicCTI-132103 (Japan Pharmaceutical Information Center; registration date February 25, 2015)

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-022-01139-5.

Influência do tramadol associado à levobupicavaína epidural sobre a taxa de propofol e variáveis fisiológicas, em cadelas submetidas à mastectomia e à ovário-histerectomia

RESUMO Objetivou-se avaliar os efeitos fisiológicos e sobre o consumo do propofol, relativos à anestesia epidural com levobupivacaína isolada ou associada a diferentes doses de tramadol. Para tal, 18 cadelas foram pré-tratadas com acepromazina, utilizando-se propofol para indução e manutenção anestésicas. Conforme o protocolo epidural instituído, formaram-se três grupos (n=6) tratados com levobupivacaína isolada (1,5mg/kg) (GL) ou acrescida de 2mg/kg (GLT2) ou 4mg/kg (GLT4) de tramadol, respectivamente. As fêmeas foram submetidas à mastectomia e à ovário-histerectomia (OH), registrando-se as variáveis fisiológicas nos períodos pré (TB e T0) e transanestésicos (T10 a T70), bem como a taxa mínima de propofol necessária. Houve redução da FC para o GL e o GLT4 em relação ao GLT2 (T30 a T70), detectando-se, no GL, redução da PAS e da PAD em relação ao TB. Maiores taxas de infusão do propofol foram necessárias para o GL (0,70±0,12mg/kg/min) em relação ao GLT2 (0,50±0,19mg/kg/min) e ao GLT4 (0,50±0,19mg/kg/min). Conclui-se que o tramadol potencializou o propofol, ao ofertar analgesia, independentemente da dose administrada. Todos os protocolos testados foram seguros e eficazes em cadelas submetidas à mastectomia e à OH.

Drug-Loaded Biocompatible Nanocarriers Embedded in Poloxamer 407 Hydrogels as Therapeutic Formulations

Hydrogels are three-dimensional networks of hydrophilic polymers able to absorb and retain a considerable amount of water or biological fluid while maintaining their structure. Among these, thermo-sensitive hydrogels, characterized by a temperature-dependent sol–gel transition, have been massively used as drug delivery systems for the controlled release of various bioactives. Poloxamer 407 (P407) is an ABA-type triblock copolymer with a center block of hydrophobic polypropylene oxide (PPO) between two hydrophilic polyethyleneoxide (PEO) lateral chains. Due to its unique thermo-reversible gelation properties, P407 has been widely investigated as a temperature-responsive material. The gelation phenomenon of P407 aqueous solutions is reversible and characterized by a sol–gel transition temperature. The nanoencapsulation of drugs within biocompatible delivery systems dispersed in P407 hydrogels is a strategy used to increase the local residence time of various bioactives at the injection site. In this mini-review, the state of the art of the most important mixed systems made up of colloidal carriers localized within a P407 hydrogel will be provided in order to illustrate the possibility of obtaining a controlled release of the entrapped drugs and an increase in their therapeutic efficacy as a function of the biomaterial used.

Tramadol Hydrochloride at Steady State Lacks Clinically Relevant QTc Interval Increases in Healthy Adults

We evaluated the effects of therapeutic and supratherapeutic doses of tramadol hydrochloride on the corrected QT (QTc) interval in healthy adults (aged 18‐55 years) in a randomized, phase I, double‐blind, placebo‐ and positive‐controlled, multiple‐dose, 4‐way crossover study. Participants were randomized to receive 1 of 4 treatments (A‐D), 1 each in 4 treatment periods (1‐4), separated by a washout period (7‐15 days). Treatment A comprised tramadol 400 mg (therapeutic dose) on days 1 through 3, tramadol 100 mg and moxifloxacin‐matched placebo on day 4, and placebo on all 4 days. Treatment B comprised tramadol 600 mg (supratherapeutic dose) on days 1 through 3, and tramadol 150 mg and moxifloxacin‐matched placebo on day 4. Treatment C comprised placebo on days 1 through 4 and moxifloxacin‐matched placebo on day 4. Treatment D comprised placebo on days 1 through 4 and moxifloxacin 400 mg on day 4. Of 68 participants enrolled, 57 (83.8%) completed the study. Both therapeutic and supratherapeutic doses of tramadol were shown to be noninferior to placebo regarding their effect on QTc prolongation. Sixty‐one of 68 (89.7%) participants reported at least 1 treatment‐emergent adverse event (mild); nausea was the most frequently reported treatment‐emergent adverse event. Summarizing, tramadol at doses up to 600 mg/day did not cause clinically relevant QTc interval prolongation in healthy adults.

Pharmacokinetics and Pharmacodynamics Evaluation of Tramadol in Thermoreversible Gels

We evaluated pharmacokinetics (PK) and pharmacodynamics (PD) induced by new formulations of tramadol (TR) in thermoreversible gels. The poloxamer- (PL-) tramadol systems were prepared by direct dispersion of the drug in solutions with PL 407 and PL 188. The evaluated formulations were as follows: F1: TR 2% in aqueous solution and F2: PL 407 (20%) + PL 188 (10%) + TR 2%; F3: PL 407 (25%) + PL 188 (5%) + TR 2%; F4: PL 407 (20%) + TR 2%. New Zealand White rabbits were divided into four groups (n = 6) and treated by subcutaneous route with F1, F2, F3, or F4 (10 μg·kg^-1). PK evaluation used TR and M1 plasma levels. PD evaluation was performed with the measurement of both pupils' diameters. F2 showed higher TR plasma concentration after 180 minutes and presented lower M1 concentrations at almost all evaluated periods. Areas under the curve (ASC_0-480 and ASC_0-∞ ) and clearance of F2 presented differences compared to F1. F2 presented significant correlation (Pearson correlation) between the enhancement of TR and M1 concentrations and the decrease of pupil size (miosis). Thus, F2 was effective in altering pharmacokinetics and pharmacodynamics effects of TR.

Prevention of catheter-related bladder discomfort - pudendal nerve block with ropivacaine versus intravenous tramadol: study protocol for a randomized controlled trial

Background

Catheter-related bladder discomfort (CRBD) is a common distressing symptom complex during the postoperative period, especially after urologic procedures with a relatively greater size urinary catheter. In this study, we will enroll male patients undergoing elective prostate surgery with urinary catheterization under general anesthesia, and we will compare the efficacy of pudendal nerve block (PNB) and intravenous tramadol in CRBD prevention.

Methods/design

This trial is a prospective, randomized controlled trial that will test the superiority of bilateral PNB with 0.33 % ropivacaine compared with intravenous tramadol 1.5 mg/kg for CRBD prevention. A total of 94 male patients undergoing elective prostate surgery with urinary catheterization after anesthesia induction will be randomized to receive either bilateral PNB with 0.33 % ropivacaine (the PNB group) or intravenous tramadol 1.5 mg/kg (the tramadol group) after the completion of surgery. The primary outcome is the incidence of CRBD. The most important secondary outcome is the severity of postoperative CRBD, and other secondary outcomes include Numeric Rating Scale (NRS) score for postoperative pain; incidence of postoperative side effects such as postoperative nausea/vomiting, sedation, dizziness, and dry mouth; postoperative requirement for tramadol as a rescue treatment for CRBD and sufentanil as a rescue analgesic for postoperative pain; and NRS score for acceptance of an indwelling urinary catheter.

Discussion

This trial is planned to test the superiority of PNB with 0.33 % ropivacaine compared with intravenous tramadol 1.5 mg/kg. It may provide a basis for a new clinical practice for the prevention of CRBD.

Trial registration

ClinicalTrials.gov identifier NCT02683070. Registered on 11 February 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1575-y) contains supplementary material, which is available to authorized users.

The Clinical Applications of Extended-Release Abuse-Deterrent Opioids

Opioids are the mainstay for treatment of acute pain and cancer pain, and also have a role in the treatment of chronic non-malignant pain. There has been, however, a growing public health problem stemming from the misuse of opioid analgesics leading to serious consequences. To deter abuse, new formulations of extended-release opioid analgesics and tamper-resistant opioids have recently been developed. The concept of abuse-deterrent extended-release opioids is relatively new and, although abuse may not be completely prevented, the utilization of such abuse-deterrent extended-release opioids could reduce this risk. Extended-release abuse-deterrent opioids have been found to have important clinical applications in cancer, acute pain, and chronic non-malignant pain for analgesia control with decreased incidence of tampering and abuse. In this review, different extended-release formulations of opioids available for clinical applications are presented with descriptions of the formulations, their physical properties, and the clinical studies performed to provide physicians with a better understanding of their uses.

Generation of serotonin neurons from human pluripotent stem cells

Serotonin neurons located in the raphe nucleus of the hindbrain have crucial roles in regulating brain functions and have been implicated in various psychiatric disorders. Yet functional human serotonin neurons are not available for in vitro studies. Through manipulation of the WNT pathway, we demonstrate efficient differentiation of human pluripotent stem cells (hPSCs) to cells resembling central serotonin neurons, primarily those located in the rhombomeric segments 2-3 of the rostral raphe, which participate in high-order brain functions. The serotonin neurons express a series of molecules essential for serotonergic development, including tryptophan hydroxylase 2, exhibit typical electrophysiological properties and release serotonin in an activity-dependent manner. When treated with the FDA-approved drugs tramadol and escitalopram oxalate, they release or uptake serotonin in a dose- and time-dependent manner, suggesting the utility of these cells for the evaluation of drug candidates.

A Descriptive Analysis of Changes in Selected Drug Groups Available to Primary Care Physicians in Israel From 2000 to 2013

Several medical and economic factors affect the process of development and introduction of new drugs and the disappearance of various medical agents from the drug market. There are no data in the existing literature on quantitative and qualitative changes in the drug market. We assessed changes in the drug market in Israel over 14 years, focusing on drug groups that, in our subjective opinion, are mainly used in primary care medicine: pain medications, lipid lowering agents, drugs for diabetes, and antihypertensives. We assessed volume of drugs and changes and trends in terms of therapeutic efficacy and safety in selected drugs in each of the groups over the study time period. We used the Medic Compendium for the analyses. Medic contains a listing of drugs that are approved and available for use in Israel. It is updated every 2 months. In 2000, there were 253 available drugs in the study groups that contained 124 active agents. In contrast, in 2013, there were 278 available drugs that contained 130 active agents. Over the study years, there was an increase in the number of drugs that are effective, "user friendly," and have a high safety profile. Our study provides the first data on quantitative and qualitative changes that have taken place in selected groups of drugs. Although the availability of the drugs in different countries is determined by multiple factors, we assumed that there are other countries with a similar situation in terms of their drug markets.

Acetaminophen and non-steroidal anti-inflammatory drugs interact with morphine and tramadol analgesia for the treatment of neuropathic pain in rats

PURPOSE

Although non-steroidal anti-inflammatory drugs and acetaminophen have no proven efficacy against neuropathic pain, they are frequently prescribed for neuropathic pain patients. We examined whether the combination of opioids (tramadol and morphine) with indomethacin or acetaminophen produce favorable effects on neuropathic pain and compared the efficacy for neuropathic pain with that for inflammatory pain.

METHODS

The carrageenan model was used as the inflammatory pain model while the tibial neuroma transposition (TNT) model was used as the neuropathic pain model. The tibial nerve is transected in the TNT model, with the tibial nerve stump then transpositioned to the lateral aspect of the hindlimb. Neuropathic pain (mechanical allodynia and neuroma pain) is observed after TNT injury. Drugs were administered orally.

RESULTS

In the carrageenan model, all drugs produced anti-allodynic effects and all drug combinations, but not tramadol + indomethacin combination, produced synergistic anti-allodynic effects. In the TNT model, tramadol and morphine, but not acetaminophen and indomethacin, produced anti-neuropathic pain effects. In the combination, with the exception of morphine + acetaminophen combination, both acetaminophen and indomethacin reduced the 50% effective dose (ED50) of tramadol and morphine as compared with the ED50s for the single drug study in the TNT model. The ED50s of tramadol and morphine in the carrageenan combination test were not statistically significantly different from the ED50s in the TNT model combination study.

CONCLUSIONS

The combination of opioids with indomethacin or acetaminophen produced a synergistic analgesic effect both in inflammatory and neuropathic pain with some exceptions. The efficacy of these combinations for neuropathic pain was not different from that for inflammatory pain.