Profiling the subjective, psychomotor, and physiological effects of tramadol in recreational drug users

10-dehydrogingerdione amends tramadol-elicited neurotransmitters disturbance and apoptosis in the brain of male rats by repleting non-enzymatic antioxidants

Tramadol is analgesic medication to relief acute and chronic pain, referred to as alternative to opioid drugs however its abuse or overdosage may resulted in neuronal toxicity. This is attributed to severe fluctuations of neurotransmitters pattern along with cerebral inflammation and oxidative damage. Present work was undertaken to illustrate the cytoprotective effect of 10-dehydrogingerdione (10-DHGD) on the brain tissues of experimental rats due to Tramadol intake and its underlying mechanism. 24 male wistar rats were randomized into 4 equal groups. Group (1), received tramadol in a dose level 20 mg/kg intrapertioneal (i.p) daily for 30 days and referred to Tramadol group. Group (2), received both of 10-DHGD (10 mg/kg, orally) one hour before tramadol intake (dose as mentioned before) daily for 30 days. Group (3) received 10-DHGD only (10 mg/kg, orally) and daily for 30 days. Group (4), received no drugs and referred to control group for comparison. Tramadol significantly reduced Norepinephrin (NE), dopamine, serotonin and glutathione (reduced) contents of Cerebral cortex. lipid peroxidation, nuclear factor kappa B (NFkB), inducible nitric oxide synthase (INOS) levels and caspase-3 immunoreactivity showed however significant increase. Of note, 10-DHGD significantly increased neurotransmitters, glutathione contents while Malondialdehyde (MDA), Nitric oxide (NO), NFkB, INOS additionally caspase-3 immunoexpression showed significant decrease i.e counteracted to certain extent tramadol effect. These findings may refer to the cytoprotective potential of 10-DHGD against the neurotoxicity exerted by tramadol intake, most probably mediated via enhancement of endogenous antioxidants system.

Competitive effects of federal and state opioid restrictions: Evidence from the controlled substance laws

A significant concern in the policy landscape of the U.S. opioid crisis is whether supply-side controls can reduce opioid prescribing without harmful substitution. We consider an unstudied policy: the federal Controlled Substance Act (CSA) restrictions placed in August 2014 on tramadol, the second most popular opioid medication. This was followed seven weeks later by CSA restrictions for hydrocodone combination products, the leading opioids on the market. Using regression discontinuity design (RDD) models, based on the timing of the (up-)scheduling changes, to explore spillover effects, we find that tightening prescribing restrictions on one opioid reduces its use, but increases prescribing of close competitors, leading to no reduction in total opioid prescriptions.This suggests that supply restrictions are not effective in reducing opioid prescribing the presence of close substitutes that remain unrestricted.

Reinforcing effect of tramadol in the rat

Tramadol is one of the most commonly prescribed analgesic opioids in various pharmacopeias. Tramadol has been linked to abuse in recent clinical investigations. However, the behavioral effects and neural substrates of the drug have not been well characterized in preclinical studies. As a result, the present study investigated the effects of tramadol on behavioral sensitizations in rats. Its impacts on cellular and molecular alterations in the brain were also investigated. In conditioned place preference (CPP) paradigm, tramadol induced behavioral as well as motor sensitizations. These effects were dramatically reduced by intraperitoneal administration of naltrexone, an opioid receptor antagonist. Tramadol caused changes in several molecular markers (pERK1/2, Δ-FosB, PKCγ, PKMζ GAD67) in the anterior cingulate cortex, which could indicate an increase in excitation within this structure. Tramadol is demonstrated in the present study to be a reinforcing drug in rats, as it increased both behavioral and motor sensitizations. Tramadol's effects are most likely due to the high levels of excitation it causes in the brain, which is mostly caused by the activation of opioid receptors.

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.

Tramadol misuse in treatment-seeking adolescents and young adults with problematic substance use - Prediction of treatment retention

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Misuse of tramadol is increasingly highlighted as a problem in adolescents and adults.

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In treatment for substance use in the young, tramadol use increased the risk of treatment drop-out.

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Tramadol misuse, hitherto little examined, requires further clinical research.

Non-medical prescription use of opioids (NMPUO) is a public health concern worldwide. Recently, tramadol misuse is increasing, but the systematic research of misuse of this specific opioid is limited. This study set out to assess the relationship between tramadol use and completion of treatment for substance use among adolescents and adults ≤ 25 years in an outpatient clinical setting. A retrospective cohort study of treatment outcome, expressed as “completion” or “non-completion” of treatment, was conducted in treatment-seeking adolescents with problematic substance use (n = 335). Data was extracted from Ung-DOK interviews, a semi-structured assessment instrument designed for adolescents with substance abuse. The study included all treatment-seeking patients at an out-patient facility in 2014–2017. A total of 26% (n = 88) were tramadol users (life-time prevalence). Twenty percent (n = 66) of all treatments were non-completed. Tramadol users were significantly more likely than non-users to drop out of treatment (35% vs 15%, p < 0.001). In multivariate logistic regression, tramadol use and age 18 and above were factors significantly associated with non-completion. Tramadol use was statistically significantly associated with non-completion of treatment. Further research addressing treatment needs and treatment completion among tramadol users is needed.

Increase of high-risk tramadol use and harmful consequences in France from 2013-2018: evidence from the triangulation of addictovigilance data

Aims

The aim of this paper is to assess recent developments in non‐medical tramadol use, tramadol use disorder, illegal procurement and deaths.

Methods

This study used repeated cross‐sectional analysis of data collected nationwide from 2013 to 2018. Analysis was conducted through multisource monitoring of the French Addictovigilance Network of: (1) validated reports of high‐risk tramadol use, (2) record systems collecting information from toxicology experts investigating analgesic‐related deaths (DTA) and deaths related to substance abuse (DRAMES), and pharmacists for forged prescriptions (OSIAP), and (3) survey of drug users, with investigation of patterns of use while visiting addiction‐specialised institutions (OPPIDUM).

Results

Despite a plateauing level of tramadol exposure in the French population, the proportion of tramadol reports increased 1.7‐fold (187 cases in 2018, 3.2% (95% confidence interval [CI]: 2.74–3.63%), versus 1.9% (95% CI: 1.49–2.42% in 2013). Trends were similar in OSIAP: 11.9% of forged prescriptions in 2018 (95% CI: 10.56–13.45%); 1.7‐fold increase; in OPPIDUM: 0.76% (95% CI: 0.55–1.02); 2.2‐fold increase; and DRAMES: 3.2% of drug abuse‐related deaths in 2018 (95% CI: 1.89–5.16) versus 1.7% in 2013 (95% CI: 0.65–3.84). Tramadol was the primary opioid in analgesic‐related deaths in DTA (45% in 2018). Two profiles of high‐risk tramadol users were identified: (1) patients treated for pain or with tramadol persistence when pain disappeared (mainly women; mean age 44 years), and (2) individuals with non‐medical use for psychoactive effects (mainly men; mean age 36 years).

Conclusion

The triangulation of the data obtained through addictovigilance monitoring evidenced a recent increase in high‐risk tramadol use. These findings have a practical impact on the limitation of the maximal duration of tramadol prescriptions.

Does tramadol dependence impair cognitive functions?

The aim of this study is to assess the effect of tramadol use on cognitive functions, especially executive functions. Thirty tramadol use disorder patients were recruited from those admitted to the toxicology departments of Menoufia University Hospitals for detoxification. Thirty controls were recruited from employees working at the faculty of medicine, Menoufia University. Both patients and controls underwent a demographic sheet and computerized cognitive battery. Patients also completed another sheet about substance use history. Urine screening for drugs was performed on all patients prior to admission. No differences regarding age, education or marital status were found between patients and controls. Tramadol-dependent patients showed cognitive impairment in the form of impaired visual-spatial memory and executive functions in comparison to controls. After detoxification, patients showed improvement regarding executive functions but not visual-spatial memory. Tramadol impairs cognitive functions in tramadol-dependent patients.

Day-to-day hedonic and calming effects of opioids, opioid craving, and opioid misuse among patients with chronic pain prescribed long-term opioid therapy

ABSTRACT

Concerns have been raised regarding the misuse of opioids among patients with chronic pain. Although a number of factors may contribute to opioid misuse, research has yet to examine if the hedonic and calming effects that can potentially accompany the use of opioids contribute to opioid misuse. The first objective of this study was to examine the degree to which the hedonic and calming effects of opioids contribute to opioid misuse in patients with chronic pain. We also examined whether the hedonic and calming effects of opioids contribute to patients' daily levels of opioid craving, and whether these associations were moderated by patients' daily levels of pain intensity, catastrophizing, negative affect, or positive affect. In this longitudinal diary study, patients (n = 103) prescribed opioid therapy completed daily diaries for 14 consecutive days. Diaries assessed a host of pain, psychological, and opioid-related variables. The hedonic and calming effects of opioids were not significantly associated with any type of opioid misuse behavior. However, greater hedonic and calming effects were associated with heightened reports of opioid craving (both P's < 0.005). Analyses revealed that these associations were moderated by patients' daily levels of pain intensity, catastrophizing, and negative affect (all P's < 0.001). Results from this study provide valuable new insights into our understanding of factors that may contribute to opioid craving among patients with chronic pain who are prescribed long-term opioid therapy. The implications of our findings for the management of patients with chronic pain are discussed.

Opioid Use and Driving Performance

INTRODUCTION

The USA is in an opioid epidemic, with an increased number of individuals taking psychoactive drugs while executing the tasks of everyday life, including operating a motor vehicle. The pharmacology of opioids has been widely studied, but the effects of opioids on psychomotor function, driving performance, and the risk of motor vehicle collision remain less clear. Clinicians are faced with the challenge of controlling patient pain while also reconciling conflicting messages from the literature about how safe it is for their patients taking opioids to engage in potentially dangerous routine tasks.

DISCUSSION

This review assesses the current literature regarding opioids as they relate to neurocognitive function, driving performance, and accident risk. Manuscripts are categorized by study context and subject matter: controlled experimental administration, illicit use, prescription use, retrospective forensic toxicology, and polydrug consumption.

CONCLUSION

Illicit use, initiation of therapy, and opioid use in combination with other psychoactive medications are contexts most clearly associated with impairment of driving-related functions and/or operation of a motor vehicle. Clinicians should counsel patients on the risk of impairment when initiating therapy, when co-prescribing opioids and other psychoactive drugs, or when a patient is suspected of having an opioid use disorder.

Cognitive impairment in patients diagnosed with tramadol dependence compared to healthy controls

Cognitive impairment is one of the consequences of substance use. We aimed to estimate the prevalence and correlates of cognitive impairment among patients with tramadol dependence in comparison with healthy controls. The sample consisted of 30 patients with tramadol dependence and 30 healthy controls. Cognitive functions were assessed using Benton Visual Retention Test- revised, Trail Making Test A and B and Wechsler Memory Scale. Patients were also subjected to the Structured Clinical Interview for diagnostic and statistical manual of mental disorders-fourth edition (DSM-IV) Axis I Disorder, the Structured Clinical Interview for DSM-IV Axis II Disorders and the Addiction Severity Index. Results showed that tramadol-dependence patients performed significantly worse than controls regarding cognitive functions, mainly manifested in impaired visual memory, visual reconstruction ability and processing, delayed memory, attention and processing speed, and visual, auditory, immediate, delayed and working memory. We found a nonsignificant negative correlation between cognitive performance and the age of patients or duration of tramadol use. Patients with tramadol dependence were more likely to have cognitive impairment than controls. This may have important clinical implications in determining the right academic and vocational programs for these individuals and adding skills training (e.g. problem solving) to their standard psychosocial treatment.

Desmetramadol Has the Safety and Analgesic Profile of Tramadol Without Its Metabolic Liabilities: Consecutive Randomized, Double-Blind, Placebo- and Active Comparator-Controlled Trials

Desmetramadol is an investigational analgesic consisting of (+) and (-) enantiomers of the tramadol metabolite O-desmethyltramadol (M1). Tramadol is racemic and exerts analgesia by monoaminergic effects of (-)-tramadol and (-)-M1, and by the opioid (+)-M1. Tramadol labeling indicates cytochrome P450 (CYP) isozyme 2D6 ultrarapid metabolizer can produce dangerous (+)-M1 levels, and CYP2D6 poor metabolizers insufficient (+)-M1 for analgesia. We hypothesized that desmetramadol could provide the safety and analgesia of tramadol without its metabolic liabilities. We conducted consecutive double-blind, randomized, placebo-controlled, 3 segment cross-over trials A and B to investigate the steady-state pharmacokinetics and analgesia of 20 mg desmetramadol and 50 mg tramadol in 103 healthy participants without (n = 43) and with (n = 60) cotreatment with the CYP inhibitor paroxetine. In the absence of CYP inhibition (trial A), 20 mg desmetramadol and 50 mg tramadol dosed every 6 hours gave equivalent steady-state (+)-M1, similar adverse events, and analgesia significantly greater than placebo, but equal to each other. In trial B, CYP inhibition significantly depressed tramadol steady-state (+)-M1, reduced its adverse events, and led to insignificant analgesia comparable with placebo. In contrast, CYP inhibition in trial B had no deleterious effect on desmetramadol (+)-M1 or (-)-M1, which gave significant analgesia as in trial A and superior to tramadol (P = .003). Desmetramadol has the safety and efficacy of tramadol without its metabolic liabilities. CLINICALTRIALS.GOV REGISTRATIONS: NCT02205554, NCT03312777 PERSPECTIVE: To our knowledge, this is the first study of desmetramadol in humans and the first to show it provides the same safety and analgesia as tramadol, but without tramadol's metabolic liabilities and related drug-drug interactions. Desmetramadol could potentially offer expanded safety and usefulness to clinicians seeking an alternative to schedule II opioids.

Use of Tramadol for Management of Opioid Use Disorders: Rationale and Recommendations

Opioids are one of the most common illicit psychoactive substances being used in India. In fact, opioid use disorders are the most common disorder presenting to the substance use disorder treatment centers across the country. Effective and evidence-based interventions are available for management of opioid use disorders. However, the treatment for opioid use disorders remains difficult to access for most of those in need in India. The current article presents the literature on the use of tramadol for the management of opioid use disorders. It also makes recommendations on the use of tramadol for the management of opioid use disorders. Tramadol offers a viable alternative to the existing options for the management of opioid use disorders. It has been found effective when used for this indication. It offers certain major advantages such as easy and wide availability and low abuse liability. It offers a good option to expand the treatment services for opioid use disorders across the country.

A Systematic Review of Laboratory Evidence for the Abuse Potential of Tramadol in Humans

Background: Tramadol is an opioid-analgesic that has shown epidemiological evidence of abuse. This review evaluates the evidence for tramadol abuse potential in humans. Methods: A systematic literature search for human abuse liability examinations of tramadol was conducted in September 2018 and yielded 13 total studies. Studies were all within-subject, double-blind, placebo-controlled human laboratory comparisons of tramadol to opioid comparators. Results are organized based upon the route of tramadol administration (oral, parenteral) and the participant population (persons with and without current opioid physical dependence). Outcomes were categorized into self-report ratings of positive and negative effects, observer-ratings of effects, time course of effects, likelihood tramadol was identified as an opioid, and tramadol self-administration. Results: Results indicated the relative abuse potential of tramadol was lower than the opioids to which it was compared. Tramadol produced highest positive effect ratings when administered orally to persons with no opioid physical dependence. Relative to other opioids, it produced substantial negative ratings, generally demonstrated a slower onset of effects, and was less likely to be identified by participants as an opioid, though it did produce a higher rate of self-administration relative to other opioids in the one study reporting that outcome. Results suggest that the abuse potential of tramadol is highest when it is administered orally to non-dependent individuals, and that it likely decreases as the dose increased and when it was administered parentally or to persons with opioid physical dependence. Conclusion: Taken together, individuals may be less likely than with other opioids to escalate tramadol doses, transition from oral to parenteral routes of administration, or continue using tramadol once opioid physical dependence develops. In that way, the human abuse potential of tramadol appears to be different from and lower than other opioid analgesic medications.

Acute tramadol enhances brain activity associated with reward anticipation in the nucleus accumbens

BACKGROUND

Tramadol is an analgesic with monoamine reuptake inhibition and μ-opioid receptor activation. Although tramadol has been widely used for treatment of various pain conditions, there is controversy over the risk of abuse potential. We examined the effects of tramadol on the reward system in humans using functional magnetic resonance imaging (fMRI) to assess the potential of tramadol for drug abuse or dependence.

METHODS

A randomized, double-blind, placebo-controlled, crossover study was conducted for 19 healthy adults under tramadol or placebo. In association with subjective mood questionnaires, monetary incentive delay (MID) task was performed to assess the neural response to reward anticipation during fMRI. Subjective mood measures and blood oxygenation level-dependent (BOLD) signal during gain and loss anticipation were compared between tramadol and placebo.

RESULTS

Tramadol significantly reduced anxiety (Z = - 2.513, p = 0.012) and enhanced vigor (Z = - 2.725, p = 0.006) compared with placebo. By Mood Rating Scale, tramadol provoked contented (Z = - 2.316, p = 0.021), relaxed (Z = - 2.236, p = 0.025), and amicable feelings (Z = - 2.015, p = 0.044) as well as increased alertness (Z = - 1.972, p = 0.049) and contentedness domains (Z = - 2.174, p = 0.030) compared with placebo. Several brain regions including nucleus accumbens (NAc) were activated during gain anticipation in the MID task under both tramadol and placebo. Tramadol increased the %BOLD signal change in NAc at +¥500 cue significantly more than the placebo (Z = - 2.295, p = 0.022).

CONCLUSION

Tramadol enhances the reward system and thereby may have abuse potential or precipitate drug abuse in human.

Cognitive Impairment and Tramadol Dependence

BACKGROUND AND OBJECTIVE

Cognitive impairment is one of the consequences of substance abuse. Tramadol abuse is a public health problem in Egypt. The objective of this study was to estimate the prevalence and correlates of cognitive impairment among tramadol-abuse patients and control subjects.

METHODS

This study included 100 patients with tramadol abuse and 100 control subjects (matched for age, sex, and education) who were recruited from Zagazig University Hospital, Egypt. Patients were divided into 2 groups: patients who used tramadol only (tramadol-alone group) and patients who used tramadol and other substances (polysubstance group). The participants were interviewed using Montreal Cognitive Assessment test and had urine screening for drugs.

RESULTS

Twenty-four percent of the cases used tramadol alone, whereas the remaining used tramadol and other substances, mainly cannabis (66%) and benzodiazepines (27%). Tramadol-abuse patients were about 3 times more likely to have cognitive impairment than control subjects (81% vs 28%). Tramadol-alone patients were more than 2 times more likely to have cognitive impairment than control subjects (67% vs 28%). Cognitive impairment was significantly associated with polysubstance abuse. There was no association between cognitive impairment and sociodemographic or clinical factors.

CONCLUSIONS

Cognitive impairment occurs commonly among tramadol-abuse patients. Memory impairment is the most common cognitive domain to be affected. There is a significant association between cognitive impairment and polysubstance abuse.

Latarjet Procedure for Anterior Shoulder Instability Due to Tramadol-Induced Seizures: A Multicenter Study

BACKGROUND

Seizures, commonly due to epilepsy, are known to cause shoulder instability. Tramadol addiction has recently been found to induce seizures in patients who exceed the recommended dose. Because of the easy accessibility and low cost of tramadol, an increasingly alarming phenomenon of tramadol abuse has been demonstrated in recent years.

PURPOSE/HYPOTHESIS

The purpose of this multicenter study was to investigate shoulder instability resulting from tramadol-induced seizure (TIS) as well as to recommended management for such shoulder instability. The hypothesis was that TIS leads to anterior shoulder dislocations with major bony defects, which favors bony reconstructive procedures as a suitable method of treatment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This prospective case series study was conducted on 73 patients (78 shoulders) who presented with anterior shoulder dislocations and a clear history of tramadol abuse. The mean age of the patients was 26.8 years, and the mean number of dislocations was 14. The mean duration of addiction was 17 months, with a mean dose of 752 mg of tramadol hydrochloride per day. Glenoid and humeral bone loss ranged from 15% to 35% and from 15% to 40%, respectively. The mean follow-up period was 28 months. All patients underwent an open Latarjet procedure.

RESULTS

Postoperative mean Rowe score and American Shoulder and Elbow Surgeons score at final follow-up (24 months) improved significantly from 20 to 84 and from 44 to 91, respectively (P < .05). The patient satisfaction rate reached 95%, and the mean period of return to work was 12.8 weeks. Five patients (9%) had postoperative seizures due to relapse of the tramadol abuse, but only 3 patients (5%) had redislocations with nonunion or breakage of the graft or hardware.

CONCLUSION

Tramadol addiction has evolved as an important cause of seizures that can result in shoulder dislocation. Anterior shoulder instability with TIS occurs mainly with higher levels of addiction and results in significant humeral and/or glenoid bone defects. The Latarjet procedure is recommended for these patients, after control of addiction, and provides 95% satisfaction at midterm follow-up.

Coadministration of tramadol with aripiprazole and venlafaxine--The effect on spatial memory functions in male rats

BACKGROUND

The impairment of memory functions is very common in patients with chronic pain, particularly in patients with existing cognitive disorders. Results of some studies confirmed that tramadol (TRM), a frequently prescribed analgesic drug, improves memory functions in humans. However, there are no studies on the effect of co-administration of TRM with antidepressants or antipsychotics on memory; therefore, the aim of this study was to evaluate the effect of concomitant use of TRM with a second generation antipsychotic-aripiprazole (ARI) and an antidepressant-venlafaxine (VEN) on memory using an animal model.

METHODS

The effect of TRM (5mg/kg)+ARI (1.5mg/kg) and TRM (5mg/kg)+VEN (20mg/kg) on memory in Wistar rats was examined using the Morris water maze test after single and chronic administration (7 and 14 days).

RESULTS

It was observed that a single and chronic administration of TRM, VEN or ARI alone, but not a combination of TRM+VEN or TRM+ARI (except for 14 days of treatment) can improve memory in rats compared to the control group. After 14 days of administration, both combinations achieved improvement similar to each drug individually and improved spatial memory in rats compared to the control animals.

CONCLUSION

It can be assumed that chronic treatment with combinations of TRM+VEN or TRM+ARI is unlikely to cause memory impairment and interfere with either any antidepressant effect of VEN or any antipsychotic effect of ARI in patients suffering from chronic pain using TRM.

Nalbuphine could decrease the rewarding effect induced by tramadol in mice while enhancing its antinociceptive activity

Nalbuphine, a kappa-opioid agonist and mu-opioid partial agonist, has been used as an analgesic or an adjuvant with morphine to attenuate the development of morphine dependence and rewarding effect. In this study, we investigated the effect of nalbuphine on tramadol rewarding effect and antinociception. Using the conditioned place preference (CPP) paradigm in mice, we demonstrated that co-administration of nalbuphine (7mg/kg, s.c.) with tramadol (70mg/kg, s.c.) during conditioning completely blocked the CPP induced by tramadol. Co-administration of nalbuphine blocked the increase in dopamine level in the nucleus accumbens induced by tramadol. These actions were accompanied by an increase rather than attenuation of the antinociceptive effect of tramadol. These results suggest that nalbuphine could have a great potential as a pharmacotherapy for tramadol abuse.

Mu opioid mediated discriminative-stimulus effects of tramadol: an individual subjects analysis

Drug discrimination procedures use dose-dependent generalization, substitution, and pretreatment with selective agonists and antagonists to evaluate receptor systems mediating interoceptive effects of drugs. Despite the extensive use of these techniques in the nonhuman animal literature, few studies have used human participants. Specifically, human studies have not routinely used antagonist administration as a pharmacological tool to elucidate the mechanisms mediating the discriminative stimulus effects of drugs. This study evaluated the discriminative-stimulus effects of tramadol, an atypical analgesic with monoamine and mu opioid activity. Three human participants first learned to discriminate 100 mg tramadol from placebo. A range of tramadol doses (25 to 150 mg) and hydromorphone (4 mg) with and without naltrexone pretreatment (50 mg) were then administered to participants after they acquired the discrimination. Tramadol produced dose-dependent increases in drug-appropriate responding and hydromorphone partially or fully substituted for tramadol in all participants. These effects were attenuated by naltrexone. Individual participant records indicated a relationship between mu opioid activity (i.e., miosis) and drug discrimination performance. Our findings indicate that mu opioid activity may mediate the discriminative-stimulus effects of tramadol in humans. The correspondence of generalization, substitution, and pretreatment findings with the animal literature supports the neuropharmacological specificity of the drug discrimination procedure.

Biochemical and neurotransmitters changes associated with tramadol in streptozotocin-induced diabetes in rats

The incidence of diabetes is increasing worldwide. Chronic neuropathic pain occurs in approximately 25% of diabetic patients. Tramadol, an atypical analgesic with a unique dual mechanism of action, is used in the management of painful diabetic neuropathy. It acts on monoamine transporters to inhibit the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA). The purpose of this study was to evaluate the effects of diabetes on the brain neurotransmitter alterations induced by tramadol in rats, and to study the hepatic and renal toxicities of the drug. Eighty Sprague-Dawley rats were divided randomly into two sets: the normal set and the diabetic set. Diabetes was induced in rats. Tramadol was administered orally once daily for 28 days. The levels of DA, NE, and 5-HT in cerebral cortex, thalamus/hypothalamus, midbrain, and brainstem were evaluated in rats. In addition, the renal toxicity and histopathological effects of the drug were assessed. The induction of diabetes altered neurotransmitter levels. Oral administration of tramadol significantly decreased the neurotransmitter levels. Diabetes significantly altered the effects of tramadol in all brain regions. Tramadol affected function and histology of the liver and kidney. The clinical effects of tramadol in diabetic patients should be stressed.

Efficacy of extended-release tramadol for treatment of prescription opioid withdrawal: a two-phase randomized controlled trial

BACKGROUND

Tramadol is an atypical analgesic with monoamine and modest mu opioid agonist activity. The purpose of this study was to evaluate: (1) the efficacy of extended-release (ER) tramadol in treating prescription opioid withdrawal and (2) whether cessation of ER tramadol produces opioid withdrawal.

METHODS

Prescription opioid users with current opioid dependence and observed withdrawal participated in this inpatient, two-phase double blind, randomized placebo-controlled trial. In Phase 1 (days 1-7), participants were randomly assigned to matched oral placebo or ER tramadol (200 or 600 mg daily). In Phase 2 (days 8-13), all participants underwent double blind crossover to placebo. Breakthrough withdrawal medications were available for all subjects. Enrollment continued until 12 completers/group was achieved.

RESULTS

Use of breakthrough withdrawal medication differed significantly (p<0.05) among groups in both phases; the 200mg group received the least amount in Phase 1, and the 600 mg group received the most in both phases. In Phase 1, tramadol 200mg produced significantly lower peak ratings than placebo on ratings of insomnia, lacrimation, muscular tension, and sneezing. Only tramadol 600 mg produced miosis in Phase 1. In Phase 2, tramadol 600 mg produced higher peak ratings of rhinorrhea, irritable, depressed, heavy/sluggish, and hot/cold flashes than placebo. There were no serious adverse events and no signal of abuse liability for tramadol.

CONCLUSIONS

ER tramadol 200mg modestly attenuated opioid withdrawal. Mild opioid withdrawal occurred after cessation of treatment with 600 mg tramadol. These data support the continued investigation of tramadol as a treatment for opioid withdrawal.

A translational pharmacology approach to understanding the predictive value of abuse potential assessments

Within the drug development industry the assessment of abuse potential for novel molecules involves the generation and review of data from multiple sources, ranging from in-vitro binding and functional assays through to in-vivo nonclinical models in mammals, as well as collection of information from studies in humans. This breadth of data aligns with current expectations from regulatory agencies in both the USA and Europe. To date, there have been a limited number of reviews on the predictive value of individual models within this sequence, but there has been no systematic review on how each of these models contributes to our overall understanding of abuse potential risk. To address this, we analyzed data from 100 small molecules to compare the predictive validity for drug scheduling status of a number of models that typically contribute to the abuse potential assessment package. These models range from the assessment of in-vitro binding and functional profiles at receptors or transporters typically associated with abuse through in-vivo models including locomotor activity, drug discrimination, and self-administration in rodents. Data from subjective report assessments in humans following acute dosing of compounds were also included. The predictive value of each model was then evaluated relative to the scheduling status of each drug in the USA. In recognition of the fact that drug scheduling can be influenced by factors other than the pharmacology of the drug, we also evaluated the predictive value of each assay for the outcome of the human subjective effects assessment. This approach provides an objective and statistical assessment of the predictive value of many of the models typically applied within the pharmaceutical industry to evaluate abuse potential risk. In addition, the impact of combining information from multiple models was examined. This analysis adds to our understanding of the predictive value of each model, allows us to critically evaluate the benefits and limitations of each model, and provides a method for identifying opportunities for improving our assessment and prediction of abuse liability risk in the future.

Miotic and subject-rated effects of therapeutic doses of tapentadol, tramadol, and hydromorphone in occasional opioid users

RATIONALE

Tapentadol is a novel analgesic that activates mu-opioid receptors and blocks norepinephrine reuptake. There is very little information available regarding the non-analgesic pharmacodynamic effects of tapentadol.

OBJECTIVES

This outpatient study evaluated the physiological, subject-rated, and performance effects of therapeutic doses of tapentadol compared to two control drugs in humans.

METHODS

This double-blind, within-subject study examined the effects of oral placebo, tapentadol (25, 50, and 75 mg), tramadol (50, 100, and 150 mg), and hydromorphone (2, 4, and 6 mg). Nine occasional opioid users completed the study. Pharmacodynamic drug effects were measured before and for 6 h after drug administration.

RESULTS

All three doses of the tested drugs produced comparable, time-dependent decreases in pupil diameter, but the effects were generally not dose dependent. The high dose of tapentadol, as well as all three doses of tramadol and hydromorphone, increased positive subject-rated effects (e.g., "Good Effects" and "Like the Drug") as a function of time. Only tramadol increased negative subject-rated effects (e.g., "Bad Effects" and "Nauseous"); however, these were of low magnitude.

CONCLUSIONS

The highest tested dose of tapentadol produced a profile of positive effects comparable to that of hydromorphone, whereas tramadol produced positive and negative subject-rated effects. The mixed findings for tramadol are consistent with previous findings indicating that it has a distinct profile of effects relative to prototypic opioids. Future research should examine the effects of higher tapentadol doses, as well as the factors contributing to the different subject-rated profile of effects observed for tramadol relative to tapentadol and hydromorphone.

Abuse liability and reinforcing efficacy of oral tramadol in humans

BACKGROUND

Tramadol, a monoaminergic reuptake inhibitor, is hepatically metabolized to an opioid agonist (M1). This atypical analgesic is generally considered to have limited abuse liability. Recent reports of its abuse have increased in the U.S., leading to more stringent regulation in some states, but not nationally. The purpose of this study was to examine the relative abuse liability and reinforcing efficacy of tramadol in comparison to a high (oxycodone) and low efficacy (codeine) opioid agonist.

METHODS

Nine healthy, non-dependent prescription opioid abusers (6 male and 3 female) participated in this within-subject, randomized, double blind, placebo-controlled study. Participants completed 14 paired sessions (7 sample and 7 self-administration). During each sample session, an oral dose of tramadol (200 and 400 mg), oxycodone (20 and 40 mg), codeine (100 and 200 mg) or placebo was administered, and a full array of abuse liability measures was collected. During self-administration sessions, volunteers were given the opportunity to work (via progressive ratio) for the sample dose or money.

RESULTS

All active doses were self-administered; placebo engendered no responding. The high doses of tramadol and oxycodone were readily self-administered (70%, 59% of available drug, respectively); lower doses and both codeine doses maintained intermediate levels of drug taking. All three drugs dose-dependently increased measures indicative of abuse liability, relative to placebo; however, the magnitude and time course of these and other pharmacodynamic effects varied qualitatively across drugs.

CONCLUSIONS

This study demonstrates that, like other mu opioids, higher doses of tramadol function as reinforcers in opioid abusers, providing new empirical data for regulatory evaluation.

Pharmacodynamic profile of tramadol in humans: influence of naltrexone pretreatment

RATIONALE

Tramadol is a prescription analgesic that activates mu opioid and monoamine receptor systems. Tramadol is thought to have limited abuse potential compared to mu opioid agonists, but laboratory data indicate that it shares some of their pharmacodynamic effects.

OBJECTIVES

This study evaluated the effect of mu opioid receptor blockade with naltrexone on the pharmacodynamic action of tramadol in humans.

METHODS

This inpatient, double-blind, randomized, within-subject study examined the effects of oral placebo, tramadol (87.5, 175, and 350 mg), and hydromorphone (4 and 16 mg; positive control) after 1 h pretreatment with oral naltrexone (0 and 50 mg). Ten recreational opioid users completed the study. Pharmacodynamic effects were measured before and for 7 h after initial drug administration.

RESULTS

Lower doses of tramadol and hydromorphone were generally placebo-like. Hydromorphone (16 mg) produced prototypic mu opioid agonist-like effects that were blocked by naltrexone. Tramadol (350 mg) produced miosis and increased ratings of "Good Effects" and "Liking" but also increased ratings of "Bad Effects." Naltrexone reversed tramadol-induced physiological effects and mydriasis emerged, but unlike results with hydromorphone, naltrexone only partially attenuated tramadol's positive subjective effects and actually enhanced several unpleasant subjective ratings.

CONCLUSIONS

Naltrexone can be used to disentangle the mixed neuropharmacological actions of tramadol. High-dose tramadol produces a mixed profile of effects. These data suggest that both mu and non-mu opioid actions play a role in tramadol's subjective profile of action.

Discriminative stimulus effects of tramadol in humans

Tramadol is an unscheduled atypical analgesic that acts as an agonist at μ-opioid receptors and inhibits monoamine reuptake. Tramadol can suppress opioid withdrawal, and chronic administration can produce opioid physical dependence; however, diversion and abuse of tramadol is low. The present study further characterized tramadol in a three-choice discrimination procedure. Nondependent volunteers with active stimulant and opioid use (n = 8) participated in this residential laboratory study. Subjects were trained to discriminate between placebo, hydromorphone (8 mg), and methylphenidate (60 mg), and tests of acquisition confirmed that all volunteers could discriminate between the training drugs. The following drug conditions were then tested during discrimination test sessions: placebo, hydromorphone (4 and 8 mg), methylphenidate (30 and 60 mg), and tramadol (50, 100, 200, and 400 mg). In addition to discrimination measures, which included discrete choice, point distribution, and operant responding, subjective and physiological effects were measured for each test condition. Both doses of hydromorphone and methylphenidate were identified as hydromorphone- and methylphenidate-like, respectively. Lower doses of tramadol were generally identified as placebo, with higher doses (200 and 400 mg) identified as hydromorphone, or opioid-like. The highest dose of tramadol increased ratings on the stimulant scale, but was not significantly identified as methylphenidate-like. Tramadol did not significantly increase subjective ratings associated with reinforcement. Taken together, these results extend previous work with tramadol as a potential medication for the treatment of opioid dependence and withdrawal, showing acute doses of tramadol exhibit a profile of effects similar to opioid agonists and may have abuse liability in certain populations.

Effects of repeated tramadol and morphine administration on psychomotor and cognitive performance in opioid-dependent volunteers

Tramadol is an atypical, mixed mechanism analgesic used to treat moderate to severe pain. Based on evidence that tramadol has relatively low abuse potential and can relieve opioid withdrawal, tramadol may be useful for treating opioid dependence. The purpose of this study was to assess the performance side-effect profile of tramadol. Nine opioid-dependent volunteers completed a performance battery following 5-7 days of subcutaneous morphine (15 mg, 4 times/day) and two doses of oral tramadol (50, 200 mg, 4 times/day) in a within subject cross-over design. Morphine was always the first condition, and the order of the two tramadol doses was randomized and double blind. Performance was significantly worse in the morphine condition relative to one or both tramadol doses on measures of psychomotor speed/coordination (circular lights task), psychomotor speed/pattern recognition (DSST speed measure) and psychomotor speed/set shifting (trail-making tasks). There were no significant differences among conditions in DSST accuracy, simple reaction time, divided attention, working memory, episodic memory, metamemory, or time estimation. Neither tramadol dose was associated with worse performance than morphine on any measure. Although practice sessions were conducted prior to the first session to reduce order effects, the possibility that residual practice effects contributed to the differences between tramadol and morphine cannot be ruled out. The high tramadol dose produced worse performance than the low dose only on the balance measure. These findings suggest that tramadol is generally a safe medication with respect to cognitive and psychomotor measures and support tramadol's further evaluation as an opioid-dependence treatment.

Physical dependence potential of daily tramadol dosing in humans

RATIONALE

Tramadol is an atypical, mixed-mechanism analgesic involving both opioid and catecholamine processes that appears to have low abuse potential and may be useful as a treatment for opioid dependence.

OBJECTIVES

The current study assessed the level of physical dependence and opioid blockade efficacy produced by daily maintenance on oral tramadol.

METHODS

Nine residential opioid-dependent adults were maintained on two doses of daily oral tramadol (200 and 800 mg) for approximately 4-week intervals in a randomized, double-blind, crossover design. The acute effects of intramuscular placebo, naloxone (0.25, 0.5, and 1.0 mg), and hydromorphone (1.5, 3.0, and 6.0 mg) were tested under double-blind, randomized conditions. Outcomes included observer- and subject-rated measures and physiologic indices.

RESULTS

Challenge doses of naloxone resulted in significantly higher mean peak withdrawal scores compared to placebo. Withdrawal intensity from naloxone was generally greater during 800 versus 200 mg/day tramadol maintenance. Mean peak ratings of agonist effects were elevated at higher hydromorphone challenge doses, but did not differ significantly between tramadol doses. Physiologic measures were generally affected by challenge conditions in a dose-dependent manner, with few differences between tramadol maintenance dose conditions.

CONCLUSIONS

Chronic tramadol administration produces dose-related opioid physical dependence, without producing dose-related attenuation of agonist challenge effects. Tramadol may be a useful treatment for patients with low levels of opioid dependence or as a treatment for withdrawal during opioid detoxification, but does not appear to be effective as a maintenance medication due to a lack of opioid cross-tolerance.

Tramadol dependence: a survey of spontaneously reported cases in Sweden

BACKGROUND

Tramadol is a weak opioid analgesic, which is generally considered to be safe. However, conflicting data exist on the dependence potential of tramadol.

OBJECTIVE

The aim of this study was to investigate occurrence of tramadol dependence and associated risk factors using spontaneously reported adverse drug reactions.

METHODS

The Swedish database for spontaneously reported adverse drug reactions, Swedish Drug Information System (SweDIS), was searched for reports on tramadol dependence from 1 January 1995 until 31 December 2006. Selection was conducted based on the DSM-IV definition of dependence. Available information was scrutinised and registered and then presented descriptively.

RESULTS

A total of 104 reports of tramadol dependence were identified, of which 60 (58%) concerned women. The median age (range) was 45 (15-84) years. Information on a history of substance abuse was present in 31 patients (30%) and 41 patients (39%) had a documented past or current use of a drug of abuse. Prescribed doses of tramadol ranged between 50-800 mg/day, and ingested doses between 50-4000 mg/day. Time of onset ranged from some weeks up to 4 years. In 72 (69%) cases the reaction was classified as serious, mainly due to hospitalisations for detoxification or discontinuation of tramadol.

CONCLUSIONS

There is an occurrence of tramadol dependence in association with analgesic treatment within the recommended dose range. In susceptible patients a severe and serious dependence syndrome may develop. A history of abuse or use of a drug of abuse seems to be an important risk factor.

Changes in the rewarding effects induced by tramadol and its active metabolite M1 after sciatic nerve injury in mice

INTRODUCTION

The present study was designed to investigate the rewarding effects induced by tramadol and its active metabolite O-desmethyltramadol (M1) under a neuropathic pain-like state.

RESULTS

In opioid receptor binding and G protein activation, we confirmed that M1, but not tramadol, showed mu-opioid receptor (MOR) agonistic activity. Furthermore, we found that the subcutaneous (s.c.) injection of tramadol and M1 each produced a significant place preference in mice, and these effects were significantly suppressed by pretreatment with the MOR antagonist beta-funaltrexamine. The dopamine level in the mouse nucleus accumbens was significantly increased by s.c. injection of either tramadol or M1. Mice with sciatic nerve ligation exhibited a marked decrease in the latency of paw withdrawal in response to a thermal stimulus only on the ipsilateral side. Under these neuropathic pain-like conditions, the rewarding effect induced by s.c. injection of either tramadol or M1 was dramatically inhibited after sciatic nerve ligation. Furthermore, the M1-induced G protein activation in the lower midbrain area was suppressed after sciatic nerve ligation.

DISCUSSION

Our present data support the notion that the rewarding effect induced by tramadol is mediated mainly through metabolism to its active metabolite M1 via MOR. Furthermore, the suppression of the M1-induced G protein activation in the lower midbrain area caused by sciatic nerve ligation may be responsible for inhibiting the rewarding effects induced by s.c. injection of tramadol and M1 under a neuropathic pain-like state.

Pharmacologic management of neuropathic pain: evidence-based recommendations

Patients with neuropathic pain (NP) are challenging to manage and evidence-based clinical recommendations for pharmacologic management are needed. Systematic literature reviews, randomized clinical trials, and existing guidelines were evaluated at a consensus meeting. Medications were considered for recommendation if their efficacy was supported by at least one methodologically-sound, randomized clinical trial (RCT) demonstrating superiority to placebo or a relevant comparison treatment. Recommendations were based on the amount and consistency of evidence, degree of efficacy, safety, and clinical experience of the authors. Available RCTs typically evaluated chronic NP of moderate to severe intensity. Recommended first-line treatments include certain antidepressants (i.e., tricyclic antidepressants and dual reuptake inhibitors of both serotonin and norepinephrine), calcium channel alpha2-delta ligands (i.e., gabapentin and pregabalin), and topical lidocaine. Opioid analgesics and tramadol are recommended as generally second-line treatments that can be considered for first-line use in select clinical circumstances. Other medications that would generally be used as third-line treatments but that could also be used as second-line treatments in some circumstances include certain antiepileptic and antidepressant medications, mexiletine, N-methyl-D-aspartate receptor antagonists, and topical capsaicin. Medication selection should be individualized, considering side effects, potential beneficial or deleterious effects on comorbidities, and whether prompt onset of pain relief is necessary. To date, no medications have demonstrated efficacy in lumbosacral radiculopathy, which is probably the most common type of NP. Long-term studies, head-to-head comparisons between medications, studies involving combinations of medications, and RCTs examining treatment of central NP are lacking and should be a priority for future research.

Modest opioid withdrawal suppression efficacy of oral tramadol in humans

RATIONALE

Tramadol is in an unscheduled atypical analgesic with low rates of diversion and abuse and mixed pharmacologic actions, including modest opioid agonist activity.

OBJECTIVES

The purpose of the current study was to characterize the opioid withdrawal suppression efficacy of oral tramadol.

MATERIALS AND METHODS

Residential, opioid-dependent adults (n = 10) were maintained on morphine (15 mg subcutaneously, quad in diem) for approximately 6 weeks. Spontaneous opioid withdrawal was produced by substituting placebo for scheduled morphine doses 17.5 h before experimental sessions that occurred twice weekly. The acute effects of placebo, tramadol (50, 100, 200, and 400 mg orally), naloxone (0.1 and 0.2 mg intramuscularly [IM]), and morphine (15 and 30 mg IM) were tested under double-blind, double-dummy, randomized conditions. Outcomes included observer- and subject-rated measures, physiologic indices, and psychomotor/cognitive task performance.

RESULTS

Naloxone and morphine produced prototypic opioid antagonist and agonist effects, respectively. Tramadol 50 and 100 mg produced effects most similar to placebo. Tramadol 200 and 400 mg initially produced significant dose-related increases in ratings of "bad effects" and "feel sick," followed by evidence of opioid withdrawal suppression. Tramadol did not produce significant increases on measures of positive drug effects nor any clinically significant physiologic changes.

CONCLUSIONS

Tramadol 200 and 400 mg show evidence of opioid withdrawal suppression without significant observer- and subject-rated opioid agonist effects. The profile of action did not suggest a high risk for tramadol abuse in opioid dependent individuals. Tramadol may be a useful medication for treating opioid withdrawal.

Neuropsychological Consequences of Opiate Use

Approximately 3.7 million individuals have used heroin and other opiate substances in their lifetime. Despite increasing knowledge of the effects of heroin, it remains the most abused opiate and use among adults has recently increased. The empirical literature examining the neurocognitive effects of acute and chronic opioid use remains limited; however, findings to date suggest that the use of opiates has both acute and long-term effects on cognitive performance. Neuropsychological data indicate deficits in attention, concentration, recall, visuospatial skills and psychomotor speed with both acute and chronic opioid use. The long-term effects of opiate use appear to have the greatest impact on executive functions, including the ability to shift cognitive set and inhibit inappropriate response tendencies. Factors that contribute to addiction and recovery are also discussed, as it is difficult to disentangle the effects of opiate use on cognitive performance from other factors that may affect neurobehavioral measures.

Endogenous opiates and behavior: 2005

This paper is the 28th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2005 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity, neurophysiology and transmitter release (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); immunological responses (Section 17).