Considering tapentadol as a first-line analgesic: 14 questions

Benzylpiperidine derivatives as new dual μ-opioid and σ1 receptor ligands with potent antinociceptive effects

Dual-acting μ-opioid receptor (MOR)/sigma-1 receptor (σ1R) ligands have displayed promise in exerting robust antinociceptive effects while reducing opioid-related side effects. To discover safer and more effective analgesics, we designed, prepared, and evaluated 30 benzylpiperidine derivatives as dual MOR and σ1R ligands. The obtained benzylpiperidine analogs were tested for MOR and σ1R binding affinity in vitro. The best compound 52 showed high affinity for both MOR [Ki (MOR) = 56.4 nM] and σ1R [Ki (σ1R) = 11.0 nM] and produced potent antinociceptive effects in the abdominal contraction test (ED50 = 4.04 mg/kg in mice), carrageenan-induced inflammatory pain model (ED50 = 6.88 mg/kg in mice), formalin test (ED50 = 13.98 mg/kg in rats) and complete Freund's adjuvant (CFA)-induced chronic pain model (ED50 = 7.62 mg/kg in mice). Moreover, 52 had less MOR-related adverse effects than oxycodone, including constipation, acute hyperlocomotion and physical dependence. The above results suggested that 52 may be a promising candidate for the development of safer analgesics.

Tramadol and Tapentadol Induce Conditioned Place Preference with a Differential Impact on Rewarding Memory and Incubation of Craving

Tramadol and tapentadol, synthetic opioids commonly prescribed for moderate-to-severe pain, have a unique pharmacology that optimizes their analgesia and safety. However, they are not devoid of risks, presenting addictive, abuse, and dependence potential. While tramadol-reinforcing properties have been documented by various studies with human and animal models, including conditioned place preference (CPP) assays, no similar studies have been performed with tapentadol. In the present study, we performed CPP assays by intraperitoneally administering Wistar rats with a tramadol/tapentadol therapeutic dose. Animal permanence and the number of entries in the CPP compartments were recorded in the preconditioning phase and then 1 (T1), 7 (T7), and 14 (T14) days after conditioning. Both opioids induced a change in place preference (T1), suggesting that they have short-term reinforcing properties. However, only tramadol was associated with place preference retention (T7 and T14), with an increase in the number of entries in the opioid-paired compartment (T1 and T7), showing that it causes rewarding memory and incubation of craving. The results indicate that at therapeutic doses: (1) both drugs cause short-term rewarding effects and (2) as opposed to tramadol, tapentadol does not cause CPP retention, despite its higher central nervous system activity and stricter scheduling.

Repeated Administration of Clinically Relevant Doses of the Prescription Opioids Tramadol and Tapentadol Causes Lung, Cardiac, and Brain Toxicity in Wistar Rats

Tramadol and tapentadol, two structurally related synthetic opioid analgesics, are widely prescribed due to the enhanced therapeutic profiles resulting from the synergistic combination between μ-opioid receptor (MOR) activation and monoamine reuptake inhibition. However, the number of adverse reactions has been growing along with their increasing use and misuse. The potential toxicological mechanisms for these drugs are not completely understood, especially for tapentadol, owing to its shorter market history. Therefore, in the present study, we aimed to comparatively assess the putative lung, cardiac, and brain cortex toxicological damage elicited by the repeated exposure to therapeutic doses of both prescription opioids. To this purpose, male Wistar rats were intraperitoneally injected with single daily doses of 10, 25, and 50 mg/kg tramadol or tapentadol, corresponding to a standard analgesic dose, an intermediate dose, and the maximum recommended daily dose, respectively, for 14 consecutive days. Such treatment was found to lead mainly to lipid peroxidation and inflammation in lung and brain cortex tissues, as shown through augmented thiobarbituric acid reactive substances (TBARS), as well as to increased serum inflammation biomarkers, such as C reactive protein (CRP) and tumor necrosis factor-α (TNF-α). Cardiomyocyte integrity was also shown to be affected, since both opioids incremented serum lactate dehydrogenase (LDH) and α-hydroxybutyrate dehydrogenase (α-HBDH) activities, while tapentadol was associated with increased serum creatine kinase muscle brain (CK-MB) isoform activity. In turn, the analysis of metabolic parameters in brain cortex tissue revealed increased lactate concentration upon exposure to both drugs, as well as augmented LDH and creatine kinase (CK) activities following tapentadol treatment. In addition, pneumo- and cardiotoxicity biomarkers were quantified at the gene level, while neurotoxicity biomarkers were quantified both at the gene and protein levels; changes in their expression correlate with the oxidative stress, inflammatory, metabolic, and histopathological changes that were detected. Hematoxylin and eosin (H & E) staining revealed several histopathological alterations, including alveolar collapse and destruction in lung sections, inflammatory infiltrates, altered cardiomyocytes and loss of striation in heart sections, degenerated neurons, and accumulation of glial and microglial cells in brain cortex sections. In turn, Masson's trichrome staining confirmed fibrous tissue deposition in cardiac tissue. Taken as a whole, these results show that the repeated administration of both prescription opioids extends the dose range for which toxicological injury is observed to lower therapeutic doses. They also reinforce previous assumptions that tramadol and tapentadol are not devoid of toxicological risk even at clinical doses.

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.

Tapentadol prolonged release for managing moderate to severe chronic neck pain with or without a neuropathic component

Background: Despite the high prevalence of neck pain, few studies have addressed the pharmacological treatment of this condition.Purpose: We evaluated the effectiveness of tapentadol prolonged-release (PR) in patients with or without a neuropathic pain component, with a focus on functional movements, disability and Quality of Life (QoL).Study design/setting: Observational, retrospective study.Patient sample: Ninety-four adult patients with severe neck pain not responsive to opioid step III treatment.Outcome measures: The primary endpoint was a ≥ 30% improvement of pain intensity at 4 weeks (W4). Several secondary outcomes were evaluated, including neck disability index (NDI), range of motion (ROM), and QoL.Methods: Patients received tapentadol PR at the starting dose of 100 mg/day. Dose titration was allowed in 50 mg increments, up to 500 mg daily.Results: At W4, the primary endpoint of ≥30% improvement of pain was reported in 70% (n = 35; 95% confidence interval [CI]: 55-82%) of patients with a neuropathic pain component and in 69% (n = 20; 95% CI: 49-85%) of those without a neuropathic component. The percentage of patients reporting a neuropathic pain component significantly decreased from baseline (64.2%) to W4 (27.8%). NDI significantly improved in both groups at W12. ROM significantly improved in all three planes of motion (p < .01), with no difference between the two groups. Interference of pain with sleep and QoL also improved.Conclusions: The reduction in pain provided by tapentadol is associated with functional recovery, which may in turn be linked to an improvement in QoL.

Tapentadol vs oxycodone/naloxone in the management of pain after total hip arthroplasty in the fast track setting: an observational study

BACKGROUND

In recent years, joint replacement surgery has gradually progressed towards the fast-track model, and early rehabilitation immediately after surgery is regarded fundamental for optimal recovery of function: the aim of the present study is to describe the efficacy in perioperative management of pain in patients undergoing total hip replacement surgery and treated with tapentadol or oxycodone/naloxone in combination with ketoprofene.

METHODS

Single-center retrospective study on patients with moderate-severe pain, referred to total hip replacement. Patients received either tapentadol (100 mg/twice-daily post-surgery - treatment group) or oxycodone/naloxone (10 mg/5 mg post-surgery - control group) plus ketoprofen 100 mg/ twice daily. Supplemental analgesia (paracetamol 1 g or morphine 0,1 mg/kg sc) was provided if needed. Pain at rest and pain during movement were evaluated on a daily basis for 4 days post-op, after which patients were usually discharged. All adverse events were reported and compared between the two groups.

RESULTS

106 patients were analyzed in the tapentadol group and compared to 105 patients treated with oxycodone/naloxone. Both pain intensity at rest and upon movement were significantly lower in the tapentadol group at all follow-up times (p < 0.001). Throughout T1-T4, supplemental analgesia was needed by significantly less tapentadol patients compared to the control group. Similarly, regarding side effects, a significantly higher occurrence of post-op nausea, vomit, itching and constipation was observed in the control group (p < 0.001 in all cases).

CONCLUSION

Results from the present study support the use of tapentadol in combination with ketoprofen for the management of moderate-severe pain in the setting of major orthopedic surgery, given its effectiveness in reducing pain intensity, and its satisfactory tolerance.

Testosterone deficiency in non-cancer opioid-treated patients

PURPOSE

The use of opioids in patients with chronic non-cancer pain is common and can be associated with opioid-induced androgen deficiency (OPIAD) in men. This review aims to evaluate the current literature regarding the prevalence, clinical consequence and management of OPIAD.

METHODS

A database search was performed in Medline, Embase and Cochrane using terms such as "analgesics", "opioids" and "testosterone". Relevant literature from January 1969 to March 2018 was evaluated.

RESULTS

The prevalence of patients with OPIAD ranges from 19 to 86%, depending on the criteria for diagnosis of hypogonadism. The opioid-induced suppression of gonadotropin-releasing and luteinizing hormones represents the main important pathogenetic mechanisms. OPIAD has significant negative clinical consequences on sexual function, mood, bone density and body composition. In addition, OPIAD can also impair pain control leading to hyperalgesia, which can contribute to sexual dysfunction and mood impairment.

CONCLUSIONS

OPIAD is a common adverse effect of opioid treatment and contributes to sexual dysfunction, impairs pain relief and reduces overall quality of life. The evaluation of serum testosterone levels should be considered in male chronic opioid users and the decision to initiate testosterone treatment should be based on the clinical profile of individuals, in consultation with the patient.

Comparative pharmacology and toxicology of tramadol and tapentadol

Moderate-to-severe pain represents a heavy burden in patients' quality of life, and ultimately in the society and in healthcare costs. The aim of this review was to summarize data on tramadol and tapentadol adverse effects, toxicity, potential advantages and limitations according to the context of clinical use. We compared data on the pharmacological and toxicological profiles of tramadol and tapentadol, after an extensive literature search in the US National Library of Medicine (PubMed). Tramadol is a prodrug that acts through noradrenaline and serotonin reuptake inhibition, with a weak opioid component added by its metabolite O-desmethyltramadol. Tapentadol does not require metabolic activation and acts mainly through noradrenaline reuptake inhibition and has a strong opioid activity. Such features confer tapentadol potential advantages, namely lower serotonergic, dependence and abuse potential, more linear pharmacokinetics, greater gastrointestinal tolerability and applicability in the treatment of chronic and neuropathic pain. Although more studies are needed to provide clear guidance on the opioid of choice, tapentadol shows some advantages, as it does not require CYP450 system activation and has minimal serotonergic effects. In addition, it leads to less side effects and lower abuse liability. However, in vivo and in vitro studies have shown that tramadol and tapentadol cause similar toxicological damage. In this context, it is important to underline that the choice of opioid should be individually balanced and a tailored decision, based on previous experience and on the patient's profile, type of pain and context of treatment.

SIGNIFICANCE

This review underlines the need for a careful prescription of tramadol and tapentadol. Although both are widely prescribed synthetic opioid analgesics, their toxic effects and potential dependence are not completely understood yet. In particular, concerning tapentadol, further research is needed to better assess its toxic effects.