Potentiation of opioid analgesia by psychostimulant drugs: a review

A novel small molecule, AS1, reverses the negative hedonic valence of noxious stimuli

BACKGROUND

Pain is the primary reason people seek medical care, with chronic pain affecting ~ 20% of people in the USA. However, many existing analgesics are ineffective in treating chronic pain, while others (e.g., opioids) have undesirable side effects. Here, we describe the screening of a small molecule library using a thermal place aversion assay in larval zebrafish to identify compounds that alter aversion to noxious thermal stimuli and could thus serve as potential analgesics.

RESULTS

From our behavioral screen, we discovered a small molecule, Analgesic Screen 1 (AS1), which surprisingly elicited attraction to noxious painful heat. When we further explored the effects of this compound using other behavioral place preference assays, we found that AS1 was similarly able to reverse the negative hedonic valence of other painful (chemical) and non-painful (dark) aversive stimuli without being inherently rewarding. Interestingly, targeting molecular pathways canonically associated with analgesia did not replicate the effects of AS1. A neuronal imaging assay revealed that clusters of dopaminergic neurons, as well as forebrain regions located in the teleost equivalent of the basal ganglia, were highly upregulated in the specific context of AS1 and aversive heat. Through a combination of behavioral assays and pharmacological manipulation of dopamine circuitry, we determined that AS1 acts via D1 dopamine receptor pathways to elicit this attraction to noxious stimuli.

CONCLUSIONS

Together, our results suggest that AS1 relieves an aversion-imposed "brake" on dopamine release, and that this unique mechanism may provide valuable insight into the development of new valence-targeting analgesic drugs, as well as medications for other valence-related neurological conditions, such as anxiety and post-traumatic stress disorder (PTSD).

Does Socioeconomic Status or Methamphetamine use Impact Discharge Opioid Requirements in Burn Injured Patients?

Methamphetamine (MA) use is associated with lower socioeconomic status (SES) and increased opioid use. Though MA use itself has been linked to larger burn injuries and increased length of stay, studies examining the effect of SES on opioid use in this patient population remain limited. The aim of this work was to examine how both SES and/or MA use in burn patients impacted discharge opioid requirements. Records of burn patients admitted to an ABA verified burn center were reviewed from January 2016 to December 2017. Patients were grouped into MA positive (MPOS) or negative groups (MNEG) based on admission urine toxicology screening. Pain scores, oral morphine opioid equivalents (OE), and adjunct pain medication use reported within 24 hours of discharge were examined. SES was determined by zip code. No difference was found between MPOS and MNEG groups regarding discharge OE (p=0.4), OE/TBSA (p=0.79), or pain score (p=0.09). Low SES was more prevalent in MPOS patients (p<0.0001) but low SES was not a predictor of discharge OE (p=0.7), OE/TBSA (p=0.7), or pain score (p = 0.15). Discharge OE and OE/TBSA requirements correlated with discharge pain score (p<0.0001) and LOS (p<0.01), but not SES. Multivariate linear regression found that MNEG status (p=0.005), pain score (p < 0.0001), concurrent use of benzodiazepines and gabapentin (p<0.001), but not low SES, were independently associated with increased OE. Although lower SES was seen in patients using MA, SES was not associated with discharge opioid use or pain scores. Additional work will be necessary to determine factors affecting opioid use in this population.

Unexpected beneficial effects of drugs: an analysis of cases in the Dutch spontaneous reporting system

INTRODUCTION

Drug use is inherently related to both beneficial effects on health as well as the occurrence of risks. The beneficial effects may be related to efficacy, the treatment range of a product, or even to user-friendliness of a product. However, in addition to the occurrence of adverse drug reactions, a drug can also have an unexpected beneficial effect on a patient's health, not related to the indication for which the drug was used. The aim of this article is to characterize the reports of unexpected beneficial effects of drugs in the Dutch spontaneous reporting system.

METHODS

A descriptive analysis was used to gain insight in number of reports and drug classes responsible for unexpected beneficial effects of drugs. Grouping of positive side effects into classes was done by a conventional qualitative content analysis of the cases.

RESULTS

Four hundred nine reports which described unexpected beneficial effects of drugs were included, which mentioned 451 associations between suspected drugs and unexpected beneficial effects. There were 147 drug classes on the 4th ATC level involved. Content analysis of the reports gave rise to 22 categories of unexpected beneficial effects of drugs, including one "other category". DISCUSSION AND CONCLUSION: The analysis showed a diverse spectrum of reported reactions and drugs with some categories of unexpected beneficial effects of drugs mentioned multiple times for certain drug classes on the 4th ATC level. Most of these findings are consistent with the existing literature and knowledge on the pharmacological mechanism of the drugs in question. Coding harmonization would make it possible to study these effects in international databases.

Periaqueductal gray/dorsal raphe dopamine neurons contribute to sex differences in pain-related behaviors

Sex differences in pain severity, response, and pathological susceptibility are widely reported, but the neural mechanisms that contribute to these outcomes remain poorly understood. Here we show that dopamine (DA) neurons in the ventrolateral periaqueductal gray/dorsal raphe (vlPAG/DR) differentially regulate pain-related behaviors in male and female mice through projections to the bed nucleus of the stria terminalis (BNST). We find that activation of vlPAG/DRDA+ neurons or vlPAG/DRDA+ terminals in the BNST reduces nociceptive sensitivity during naive and inflammatory pain states in male mice, whereas activation of this pathway in female mice leads to increased locomotion in the presence of salient stimuli. We additionally use slice physiology and genetic editing approaches to demonstrate that vlPAG/DRDA+ projections to the BNST drive sex-specific responses to pain through DA signaling, providing evidence of a novel ascending circuit for pain relief in males and contextual locomotor response in females.

Analysis of application of dental sedation in attention deficit hyperactivity disorder (ADHD) patients using the Korean National Health Insurance data

Background

Attention deficit hyperactivity disorder (ADHD) is characterized by a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development. It has a worldwide pooled prevalence of 5.29%. The characteristics of ADHD can increase the probability of dental treatment, while special behavior management can be required to allow proper treatment. In South Korea, the use of sedation in dental treatment has rapidly increased in recent decades. The present study aimed to investigate the trend and effects of sedation in patients with ADHD undergoing dental treatment in South Korea.

Methods

The study used customized health information data provided by the Korean National Health Insurance Service. Among patients with the record of sedative use during the period from January 2007 to September 2019, those with International Classification of Diseases-10 codes for ADHD (F90, F91) were selected; the data of their overall insurance claims for dental treatment were then analyzed. The patients' age, gender, sedative use, and dental treatment were analyzed per year. The annual number of general anesthesia or sedation cases was also analyzed, and changes in the method of behavior management with increasing age were examined.

Results

The study involved 7,654 patients with ADHD (6,270 males; 1,384 females). The total number of dental treatments was 137,778, while the number of sedation cases was 16,109, among which 13,052 involved male patients and 3,057 female patients. The number of general anesthesia cases was 631, among which 538 involved male patients and 93 female patients. The most frequently used sedation method in the dental treatment of patients with ADHD was N₂O inhalation. The percentage of sedation cases was highest in patients aged 4 years, and it decreased with increasing age.

Conclusion

In South Korea, both sedation and dental treatments were slightly more common in patients with ADHD than in the general population. With increasing age, the frequency of dental treatments and the percentage of sedation cases decreased.

Amphetamine Modulation of Long-Term Object Recognition Memory in Rats: Influence of Stress

Amphetamine is a potent psychostimulant that increases brain monoamine levels. Extensive evidence demonstrated that norepinephrine is crucially involved in the regulation of memory consolidation for stressful experiences. Here, we investigated amphetamine effects on the consolidation of long-term recognition memory in rats exposed to different intensities of forced swim stress immediately after training. Furthermore, we evaluated whether such effects are dependent on the activation of the peripheral adrenergic system. To this aim, male adult Sprague Dawley rats were subjected to an object recognition task and intraperitoneally administered soon after training with amphetamine (0.5 or 1 mg/kg), or its corresponding vehicle. Rats were thereafter exposed to a mild (1 min, 25 ± 1°C) or strong (5 min, 19 ± 1°C) forced swim stress procedure. Recognition memory retention was assessed 24-h after training. Our findings showed that amphetamine enhances the consolidation of memory in rats subjected to mild stress condition, while it impairs long-term memory performance in rats exposed to strong stress. These dichotomic effects is dependent on stress-induced activation of the peripheral adrenergic response.

Behavioral Battery for Testing Candidate Analgesics in Mice. I. Validation with Positive and Negative Controls

This study evaluated a battery of pain-stimulated, pain-depressed, and pain-independent behaviors for preclinical pharmacological assessment of candidate analgesics in mice. Intraperitoneal injection of dilute lactic acid (IP acid) served as an acute visceral noxious stimulus to produce four pain-related behaviors in male and female ICR mice: stimulation of 1) stretching, 2) facial grimace, 3) depression of rearing, and 4) depression of nesting. Additionally, nesting and locomotion in the absence of the noxious stimulus were used to assess pain-independent drug effects. These six behaviors were used to compare effects of two mechanistically distinct but clinically effective positive controls (ketoprofen and oxycodone) and two negative controls that are not clinically approved as analgesics but produce either general motor depression (diazepam) or motor stimulation (amphetamine). We predicted that analgesics would alleviate all IP acid effects at doses that did not alter pain-independent behaviors, whereas negative controls would not. Consistent with this prediction, ketoprofen (0.1-32 mg/kg) produced the expected analgesic profile, whereas oxycodone (0.32-3.2 mg/kg) alleviated all IP acid effects except depression of rearing at doses lower than those that altered pain-independent behaviors. For the negative controls, diazepam (1-10 mg/kg) failed to block IP acid-induced depression of either rearing or nesting and only decreased IP acid-stimulated behaviors at doses that also decreased pain-independent behaviors. Amphetamine (0.32-3.2 mg/kg) alleviated all IP acid effects but only at doses that also stimulated locomotion. These results support utility of this model as a framework to evaluate candidate-analgesic effects in a battery of complementary pain-stimulated, pain-depressed, and pain-independent behavioral endpoints. SIGNIFICANCE STATEMENT: Preclinical assays of pain and analgesia often yield false-positive effects with candidate analgesics. This study used two positive-control analgesics (ketoprofen, oxycodone) and two active negative controls (diazepam, amphetamine) to validate a strategy for distinguishing analgesics from nonanalgesics by profiling drug effects in a battery of complementary pain-stimulated, pain-depressed, and pain-independent behaviors in male and female mice.

D-Amphetamine Accelerates Recovery of Consciousness and Respiratory Drive After High-Dose Fentanyl in Rats

In the United States, fentanyl causes approximately 60,000 drug overdose deaths each year. Fentanyl is also frequently administered as an analgesic in the perioperative setting, where respiratory depression remains a common clinical problem. Naloxone is an efficacious opioid antagonist, but it possesses a short half-life and undesirable side effects. This study was conducted to test the hypothesis that d-amphetamine ameliorates respiratory depression and hastens the return of consciousness following high-dose fentanyl. Behavioral endpoints (first head movement, two paws down, and return of righting), arterial blood gas analysis and local field potential recordings from the prefrontal cortex were conducted in adult rats after intravenous administration of of fentanyl (55 µg/kg) at a dose sufficient to induce loss of righting and respiratory depression, followed by intravenous d-amphetamine (3 mg/kg) or saline (vehicle). D-amphetamine accelerated the time to return of righting by 36.6% compared to saline controls. D-amphetamine also hastened recovery of arterial pH, and the partial pressure of CO2, O2 and sO2 compared to controls, with statistically significant differences in pH after 5 min and 15 min. Local field potential recordings from the prefrontal cortex showed that within 5 min of d-amphetamine administration, the elevated broadband power <20 Hz produced by fentanyl had returned to awake baseline levels, consistent with the return of consciousness. Overall, d-amphetamine attenuated respiratory acidosis, increased arterial oxygenation, and accelerated the return of consciousness in the setting of fentanyl intoxication. This suggests that d-amphetamine may be a useful adjunct or alternative to opioid receptor antagonists such as naloxone.

Comparing the Antinociceptive Effects of Methamphetamine, Buprenorphine, or Both After Chronic Treatment and Withdrawal in Male Rats

Introduction:

Methamphetamine (Meth) and Buprenorphine (BUP) modulate pain perception. However, the antinociceptive effects of their interactions, which affect through different systems, are unclear in rats. This study aimed to compare the analgesic effects of Meth, BUP, and their coadministration, as well as the effect of withdrawal from these substances on nociception in male rats.

Methods:

In this experiment, 40 male Wistar rats (weight: 250–300 g) were categorized into four groups: control, Meth, BUP, or BUP+Meth. After seven days of treatments, the antinociceptive effects were assessed using the hot plate and the tail flick tests. The differences among the groups were analyzed with ANOVA and Tukey’s post hoc tests. P values less than 0.05 were considered significant.

Results:

Meth and BUP increased the reaction times during the hot plate and tail flick tests. The combination of Meth and BUP increased reaction time more than Meth or BUP alone.

Conclusion:

The significantly high reaction times in rats treated with Meth and BUP indicate that these substances have antinociceptive effects. In addition, Meth enhanced the antinociceptive effects of BUP. These synergistic effects might occur through the dopaminergic, serotonergic, and or adrenergic systems.

Sex-dependent modification by chronic caffeine of acute methamphetamine effects on anxiety-related behavior in rats

For fourteen days, male and female PVG/c hooded rats were provided continuously with either pure drinking water, or water containing caffeine in a quantity approximating a daily dose of 31.1 mg/kg. Then at intervals of 3 days, they were administered 1, 2 mg/kg methamphetamine (MA) or saline before being tested for anxiety-related behavior in a zero maze or a light/dark box, or their short-term spatial memory was assessed in a Y maze following introduction of a novel brightness change in one of the arms. Each rat experienced each type of apparatus with the same acute MA or saline treatment while still exposed to chronic caffeine or pure drinking water. While chronic caffeine on its own did not affect any behavioral measure, acute MA was anxiolytic for male rats suggested by increased entries and occupancy of zero-maze enclosed areas, and decreased emergence latencies and increased entries into the light/dark-box light compartment. Females were less affected than males by MA in both types of apparatus unless they also consumed caffeine. For male rats, choices of the Y-maze novel arm were affected by neither caffeine nor MA, but for females provided with unadulterated water, such choices were reduced by 1 mg/kg MA but increased for those exposed to caffeine, thereby suggesting either impaired or improved memory respectively. However, changes in anxiety could also explain these results. Overall, results generated in the three types of apparatus supported potentiation by caffeine of any effects of MA on anxiety for females only.

Methylphenidate attenuates the response to cold pain but not to aversive auditory stimuli in healthy human: a double-blind randomized controlled study

This double-blind, crossover, randomized placebo-controlled study found that methylphenidate has a specific effect on nociceptive pathways rather than a generalized effect on aversive sensory modalities.

Introduction:

We recently showed that the psycho-stimulant norepinephrine–dopamine reuptake inhibitor methylphenidate (MP) prolonged cold pain threshold and tolerance in adults with attention-deficit hyperactivity disorder (ADHD).

Objectives:

The objectives of the present study were to: (1) examine whether MP has antinociceptive properties in healthy men; (2) test MP's effects on responses to aversive auditory stimuli. The underlying aim was to determine whether MP exerts antinociceptive properties or more generalized, nonspecific attenuating effects on different aversive sensory modalities.

Methods:

This double-blind, crossover, randomized placebo-controlled study consisted of 2 sessions one week apart from each other. In each session, pain threshold (seconds) and tolerance (seconds) in response to painful cold stimulation were measured. Additionally, threshold (dB) and tolerance (seconds) to loud aversive auditory stimuli (500 Hz, 2000 Hz and white noise) were also tested prior to and 2 hours following the administration of a single dose of either 20 mg MP or an identical looking placebo.

Results:

Forty men, 26.1 ± 4.0 (mean ± SD) years were enrolled in the study. Wilcoxon signed-rank test analyses showed that MP, but not the placebo, produced a significant increase in cold pain threshold (from 4.1 ± 2.6 to 5.4 ± 3.1 seconds, P = 0.001 and from 4.5 ± 2.6 to 4.3 ± 2.7 seconds, P = 0.2, respectively) and tolerance (from 57.8 ± 54.0 to 73.8 ± 61.8 seconds, P = 0.001 and from 52.5 ± 53.7 sec to 57.0 ± 52.9 seconds, P = 0.1, respectively). No significant changes were found in any of the auditory parameters.

Conclusion:

These results suggest that MP has an effect on nociceptive pathways rather than a nonspecific, generalized attenuating effect on aversive sensory stimuli.

The Effect of Combined Treatment of Opioids With Methylphenidate on Nociception in Rats and Pain in Human

Methylphenidate hydrochloride (MPH/Ritalin) is a stimulant used for off-label management of cancer-related fatigue and sedation; however, its use in pain treatment is still relatively rare. This study 1) compares the antinociceptive effect of MPH and its combination with morphine (MOR) in adult male Wistar rats after a single administration of MPH, MOR or their combination, and 2) compares the analgesic effects of opioids and Ritalin combined therapy with opioid monotherapy in patients with cancer pain. To objectively assess physical activity during a three-week monitoring period, patients were equipped with Actiwatch Score Actigraph. Patients performed daily evaluations of pain intensity and frequency, and the extent to which pain interfered with their daily life. Our research with rats supports the evidence that MPH in lower doses has the ability to enhance the analgesic properties of morphine when the two drugs are used in combination. Results from the patient arm of our study found that short-term treatment had no significant effect on intensity or frequency of pain, however it decreased the overall burden of pain; the combined treatment of opioid and Ritalin also showed anti-sedation effects and resulted in mild improvement in one of our patient’s quality of life.

Psychiatric agents and implications for perioperative analgesia

The use of antidepressants, anxiolytics, mood stabilizers, anticonvulsants, and major tranquilizers introduces neurochemical, behavioral, cognitive, and emotional factors that increase the complexity of medical and surgical tasks. Increasingly, various classes of psychotropic medications are being prescribed in the perioperative setting for their analgesic properties in patients with or without a psychiatric diagnosis. In many cases, the precise mechanisms of action and dose-response relationships by which these agents mediate analgesia are largely unclear. An appreciation of the side effects and adverse-effect profiles of such medications and familiarity with the clinically relevant drug interactions that may occur in the perioperative setting are imperative to ensure the best possible outcome in dealing with patients on these medications. This review focuses on various classes of psychotropic agents, which are addressed individually, with particular focus on their analgesic properties. The latest published research is summarized, deficiencies in our current collective knowledge are discussed, and evidence-based recommendations are made for clinical practice.

Common biological pathways underlying the psychoneurological symptom cluster in cancer patients

BACKGROUND

A symptom cluster is a group of symptoms that occur together and are interrelated. The clinical implication of symptom cluster research is to use the clustering patterns of symptoms to understand the mechanisms for these symptoms and develop management strategies targeted at multiple symptoms.

OBJECTIVE

The purposes of this review were to summarize the evidence for a psychoneurological symptom cluster in cancer patients, to provide information regarding the underlying biological mechanisms for each of the psychoneurological symptoms within the cluster, and to propose possible common biological pathways that may underlie this cluster.

METHODS

A systematic review of the literature was conducted.

RESULTS

Empirical evidence exists to support a cluster of psychoneurological symptoms (ie, depressive symptoms, cognitive disturbance, fatigue, sleep disturbance, pain). At a molecular level, common biological pathways (ie, proinflammatory cytokines, hypothalamic-pituitary-adrenal axis, and monoamine neurotransmission system) may underlie the development of symptoms within this cluster. Activation of proinflammatory cytokines is proposed as a first stage of mechanistic pathway. However, other biological factors, such as lowered estrogen or hemoglobin levels, may influence psychoneurological cluster.

CONCLUSION

Additional studies are needed to confirm the roles of cytokines as well as other biological factors in the development of the psychoneurological cluster and to determine the biomarkers to identify the subgroups of cancer patients who are at greatest risk for this cluster.

IMPLICATIONS FOR PRACTICE

This information can be used by researchers and clinicians to guide the selection of symptom management strategies that are ideally targeted to the biological mechanisms that underlie this symptom cluster.

Days with pain and substance use disorders: is there an association?

OBJECTIVES

We investigated possible associations between pain frequency and the 5 most common substance use disorders: alcohol abuse/dependence, cocaine abuse/dependence, methamphetamine abuse/dependence, opioid abuse/dependence, and marijuana abuse/dependence.

METHODS

We used data from the Rural Stimulant Study, a longitudinal (7 waves), observational study of at-risk stimulant users (cocaine and methamphetamine) in Arkansas and Kentucky (n=462). In fixed-effects logistic regression models, we regressed our measures of substance use disorders on the number of days with pain in the past 30 days and depression severity.

RESULTS

Time periods when individuals had 1 to 15 days [odds ratio (OR)=1.85, P<0.001] or 16+ days (OR=2.18, P<0.001) with pain in the past 30 days were more likely to have a diagnosis of alcohol abuse/dependence, compared with time periods when individuals had no days with pain. Compared with time periods when individuals had no pain days in the past 30 days, time periods when individuals had 16+ pain days were more likely to have a diagnosis of opioid abuse/dependence (OR=3.32, P=0.02). Number of days with pain was not significantly associated with other substance use disorders.

DISCUSSION

Pain frequency seems to be associated with an increased risk for alcohol abuse/dependence and opioid abuse/dependence in this population, and the magnitude of the association is medium to large. Further research is needed to investigate this in more representative populations and to determine causal relationships.

Behavioral and Antinociceptive Effects of Different Psychostimulant Drugs in Prenatally Methamphetamine-Exposed Rats

Prenatal exposure to methamphetamine (METH) increases nociceptive sensitivity in adult rats. As the strong analgesics have high abuse potential and drugs of abuse are known to have analgesic properties, the aim was to study analgesic effect of different psychostimulants in control and prenatally METH-exposed rats. Latencies of withdrawal reflexes of hind limbs and the tail on thermal nociceptive stimuli were repeatedly measured in 15-min intervals after the application of 5 mg/kg s.c. of amphetamine (AMPH), methamphetamine (METH), cocaine (COC), 3,4-methylenedioxymethamphetamine (MDMA) or morphine (MOR). In all groups, AMPH induced on hind limbs stronger analgesia than METH and MDMA whereas COC and MOR were practically without any effect. On the tail, effect of AMPH did not differ from that of MOR. All psychostimulants increased defecation in comparison with MOR and in all groups the number of defecation boluses positively correlated with analgesia of the hind limbs. We did not confirm that prenatal exposure to METH makes adult rats more sensitive either to same drug or to other psychostimulants. The different analgesic potencies of psychostimulants and MOR at different body sites indicate the possible existence of a somatotopic organization of pain inhibition, which is controlled by different mechanisms.

Depression in medically ill patients

In medically ill patients, given the many entities the phenotype of depression may represent, clinicians must be prepared to cast their diagnostic nets widely, not settling for the obvious but frequently incorrect choice of major depressive episode and throwing antidepressants at it willy nilly. Having chosen the correct diagnosis from among a broad differential of depression “look-alikes,” clinicians can draw upon a broad swath of treatment modalities including medications, psychotherapy, social supports, and spiritual interventions. Working as a psychiatrist in the medical arena requires the curiosity and analytic skills of a detective and the breadth of knowledge of a polymath adapting therapeutic tools from across the biopsychosociospiritual spectrum to the specific needs of the patient.

Preclinical and early clinical investigations related to monoaminergic pain modulation

The balance between descending controls, both excitatory and inhibitory, can be altered in various pain states. There is good evidence for a prominent alpha(2)-adrenoceptor-mediated inhibitory system and 5-HT(3) (and likely also 5-HT(2)) serotonin receptor-mediated excitatory controls originating from brainstem and midbrain areas. The ability of cortical controls to influence spinal function allows for top-down processing through these monoamines. The links between pain and the comorbidities of sleep problems, anxiety, and depression may be due to the dual roles of noradrenaline and of 5-HT in these functions and also in pain. These controls appear, in the cases of peripheral neuropathy, spinal injury, and cancer-induced bone pain to be driven by altered peripheral and spinal neuronal processes; in opioid-induced hyperalgesia, however, the same changes occur without any pathophysiological peripheral process. Thus, in generalized pain states in which fatigue, mood changes, and diffuse pain occur, such as fibromyalgia and irritable bowel syndrome, one could suggest an abnormal engagement of descending facilitations with or without reduced inhibitions but with central origins. This would be an endogenous central malfunction of top-down processing, with the altered monoamine systems underlying the observed symptoms. A number of analgesic drugs can either interact with or have their actions modulated by these descending systems, reinforcing their importance in the establishment of pain but also in its control.

Methylphenidate for the treatment of depressive symptoms, including fatigue and apathy, in medically ill older adults and terminally ill adults

BACKGROUND

Depressive symptoms, fatigue, and apathy are common symptoms among medically ill older adults and patients with advanced disease, and have been associated with morbidity and mortality. Methylphenidate has been used to treat these symptoms because of its rapid effect. Despite the long history of methylphenidate use for the treatment of depressive symptoms, fatigue, and apathy, there is little definitive evidence to support its use.

OBJECTIVE

The aim of this paper was to review the efficacy and tolerability of methylphenidate in the treatment of depressive symptoms, fatigue, and apathy in medically ill older adults and adults receiving palliative care.

METHODS

English-language articles presenting systematic reviews, clinical trials, or case series describing the use of methylphenidate for the treatment of depressive symptoms, fatigue, or apathy in medically ill older adults or adults receiving palliative care were identified. The key words methylphenidate and either depressive, depression, fatigue, or apathy were used to search the Cochrane Database, MEDLINE, PsycINFO, and International Pharmaceutical Abstracts. Included articles addressed depressive symptoms, fatigue, or apathy in (1) older adults (generally, age > or =65 years), particularly those with comorbid medical illness; (2) adults receiving palliative care; and (3) adults with other chronic illnesses. I excluded articles regarding treatment of depression in healthy young adults; bipolar disorder and attention-deficit/hyperactivity disorder; and narcolepsy, chronic fatigue syndrome, and related disorders.

RESULTS

A total of 19 controlled trials of methylphenidate in medically ill older adults or patients in palliative care were identified. Unfortunately, their conflicting results, small sample sizes, and poor methodologic quality limited the ability to draw inferences regarding the efficacy of methylphenidate, although evidence of tolerability was stronger. The available evidence suggests possible effectiveness of methylphenidate for depressive symptoms, fatigue, and apathy in various medically ill populations.

CONCLUSION

In the absence of definitive evidence of effectiveness, trials of low-dose methylphenidate in medically ill adults with depression, fatigue, or apathy, with monitoring for response and adverse effects, are appropriate.

A randomized, double-blind, placebo-controlled trial assessing the impact of dexamphetamine on fatigue in patients with advanced cancer

Fatigue is very common in patients with cancer. Current guidelines suggest that psychostimulants are "reasonable to consider for severe fatigue." This randomized, double-blind, placebo-controlled trial investigated the hypothesis that dexamphetamine in fatigued patients with advanced cancer would produce a clinically significant improvement with minimal side effects. Fifty patients with advanced cancer, who were receiving palliative care, were randomized to dexamphetamine 10mg twice daily or placebo for eight days. Effectiveness was assessed using the Brief Fatigue Inventory and the McGill Quality-of-Life Questionnaire. The side effects were recorded. The results were analyzed on an intention-to-treat basis. The baseline demographics, fatigue levels, and quality-of-life scores were similar between the two arms. Patients were elderly, had impaired performance status (Eastern Cooperative Oncology Group score=3), and were taking a range of neurologically active medications. Thirty-nine patients completed the trial. There was a transient improvement in the fatigue levels on day 2, but no significant difference in fatigue (P=0.267) or quality of life (P=0.579) by the end of the study. Statistical modeling did not reveal any significant predictors of response to dexamphetamine. These results suggest that dexamphetamine 20mg daily, although well tolerated, does not significantly improve fatigue or quality of life in patients with advanced cancer, as measured by the selected instruments.

Khat chewing from the pharmacological point of view: an update

Khat chewing is deeply rooted in the every day life of people living in the Horn of Africa and in South Arabia, where Catha edulis is endemic. Considered little more than an exotic habit producing just mild pharmacological effects, systematic investigations on its active principles have instead lead to the isolation and chemical characterization of cathinone, a compound structurally related to amphetamine. Three decades of intense experimental and clinical research on khat have depicted a consistently clear picture of its pharmacological and toxicological effects.

DNA based customized nutraceutical "gene therapy" utilizing a genoscore: a hypothesized paradigm shift of a novel approach to the diagnosis, stratification, prognosis and treatment of inflammatory processes in the human

We hypothesize that using a multi-variant nutrigenomic index for the purposes of customizing or adjusting the formulation of nutritional supplements will result in an improved and novel approach to the diagnosis, stratification, prognosis, and treatment of inflammatory processes in the human. This multi-variant genetic index, or Genoscore, is derived by analyzing genotype and/or phenotype through measuring multiple genetic mutations of single nucleotide polymorphisms, gene expression, or other forms of genetic and phenotypic measurements. We also propose that manipulation of neurochemical reward circuitry in the mesolimbic brain region providing dopamine release at the nucleus accumbens (NAc), will have both pain and stress relief benefists, which are a cornerstone to the human inflammatory process. This hypothesis, applies to all genes currently discovered or which will be discovered and any nutritional or dietary supplement ingredient currently available or which will become available. For example, if a DNA test was measuring two genes through single nucleotide polymorphisms (Gene A and Gene B), the index scores (Genoscore) that would be reported to the clinician and patient would be based upon the number of mutations. An index score of 0 would mean no mutation. An index score of 1 may mean a mutation in Gene A. An Index Score of 2 may mean a mutation in Gene B. An Index Score of 3 may mean a mutation in Gene A and Gene B, resulting in a simple report, easily understandable to both the clinician and patient that provides insights into disease diagnosis, stratification, prognosis, as well as the metabolism, efficacy and/or toxicity associated with specific vitamins, minerals, herbal supplements, homeopathic ingredients and other ingredients in the nutritional and/or dietary supplement regimen. Furthermore, we have provided support that evidence shows the importance of the dopaminergic connection as an anti-pain and anti-stress molecule, working at the mesocorticolimbic region of the brain, specifically at the NAc. Additionally, we have provided support that clinical evidence demonstrates the effectiveness and safety of natural substances for joint health, such as glucosamine sulfate , chondroitin sulfate, and Ganoderma lucidum.

Douleur chronique et altération cognitive, une association méconnue

Chronic pain can induce changes in cognitive processes. The neurophysiological mechanisms involved are unclear, but the data suggest a mechanism independent of pain intensity and etiology but related to the type of pain and the time it has been chronic. Patients suffer from the cognitive changes, or at least attentional and concentration problems, as well as from the consequent handicap and life changes due to the pain, which limits or modifies their capacity to react appropriately to the pain and the challenges of daily life. The possible existence of significantly impaired cognitive processing should be taken into account during the assessment of chronic pain and in initiating therapeutic strategies.

Analgesic and behavioral effects of amphetamine enantiomers, p-methoxyamphetamine and n-alkyl-p-methoxyamphetamine derivatives

The analgesic effects of (+)- and (-)-amphetamine (AMPH), (+/-)-p-methoxyamphetamine (MA), (+/-)-N-methyl-p-methoxyamphetamine (MMA) and (+/-)-N-ethyl-p-methoxyamphetamine (EMA) were compared using two different algesimetric tests in rats. In the formalin test, (+)-AMPH elicited significant antinociception at doses of 0.2, 2 and 8 mg/kg (i.p.); (-)-AMPH was active at 2 and 8 mg/kg, but not at 0.2 mg/kg; MA elicited very potent and long-lasting antinociception; MMA was less active than MA; EMA showed significant effects only at doses of 2 and 8 mg/kg. In the C-fiber evoked nociceptive reflex assay, i.v. (+)- and (-)-AMPH were ineffective, but the methoxy derivatives showed a similar pattern of action combining inhibitory and excitatory actions. To clarify apparent discrepancies between both algesimetric tests, some behavioral motor performance tests were carried out. These tests confirm the motor stimulatory properties of (+)-AMPH, not shared by the methoxylated amphetamine derivatives. The three methoxy derivatives elicited some stereotypies related to dopaminergic activation such as grooming behavior. (+)-AMPH was also the only drug to increase the acquisition of CARs while MA and EMA were without effect. Avoidance conditioning was seriously impaired in rats injected with MMA. This conditioned behavior can be related to the significant decrease of spontaneous motor activity observed with this drug. In conclusion, the introduction of a para-methoxy group strongly increases the analgesic effects of amphetamine without its stimulatory behavioral effects. The introduction of N-alkyl substituents decreases the analgesic potency of MA.

Adjuvant Analgesics in Cancer Pain Management

Adjuvant analgesics are defined as drugs with a primary indication other than pain that have analgesic properties in some painful conditions. The group includes numerous drugs in diverse classes. Although the widespread use of these drugs as first-line agents in chronic nonmalignant pain syndromes suggests that the term "adjuvant" is a misnomer, they usually are combined with a less-than-satisfactory opioid regimen when administered for cancer pain. Some adjuvant analgesics are useful in several painful conditions and are described as multipurpose adjuvant analgesics (antidepressants, corticosteroids, alpha(2)-adrenergic agonists, neuroleptics), whereas others are specific for neuropathic pain (anticonvulsants, local anesthetics, N-methyl-D-aspartate receptor antagonists), bone pain (calcitonin, bisphosphonates, radiopharmaceuticals), musculoskeletal pain (muscle relaxants), or pain from bowel obstruction (octreotide, anticholinergics). This article reviews the evidence supporting the use of each class of adjuvant analgesic for the treatment of pain in cancer patients and provides a comprehensive outline of dosing recommendations, side effects, and drug interactions.

The effect of donepezil on sedation and other symptoms in patients receiving opioids for cancer pain: a pilot study

Opioid-induced sedation is a major complication in patients with cancer pain. This study assessed the effectiveness of donepezil in opioid-induced sedation and related symptoms in patients with cancer pain. Twenty-seven patients who were receiving strong opioids for pain and reported sedation were enrolled. Donepezil 5 mg was given every morning for 7 days. Changes between baseline and Day 7 in sedation, pain, fatigue and other symptoms were evaluated using the Edmonton Symptom Assessment Scale. Fatigue was also measured using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue). Overall usefulness of donepezil was measured by the patient at the end of the study. In 20 evaluable patients, sedation, fatigue, anxiety, well-being, depression, anorexia and problems with sleep were significantly improved. Side effects included nausea, vomiting, diarrhea, muscle and abdominal cramps, and anorexia. Overall, however, the treatment was well tolerated. Donepezil appears to improve sedation and fatigue in patients receiving opioids for cancer pain. Randomized controlled trials of this agent are justified.

Opioids: a review

Recent discoveries in opioid pharmacology help explain the enormous variability in clinical responses to these powerful analgesics. Although there is only one m opioid receptor gene, splice variants of that gene's expression result in a panoply of different functioning receptors. Other sources of variable response include polymorphisms in the m opioid receptor regulatory region, and pharmacokinetic differences because of cytochrome P-450 mono-oxygenase heterogeneity. Analgesic tolerance is likely the key phenomenon limiting the benefit of opioids. A plethora of intracellular pathways affects this. Among them are the N-methyl-D-aspartate receptor, protein kinase C gamma activity, nitric oxide synthase, and GM1 ganglioside content of the neuronal membrane. Clinical studies undercut the routine use of meperidine in most settings. Other studies have shown better ways to diminish opioid side effects.

Palliative care of the chronically critically ill patient

Evidence is accumulating that distressing physical and emotional symptoms are prevalent among patients with critical illness, including those requiring prolonged mechanical ventilation, and that suffering is underestimated and undertreated by caregivers. Although patients and their families rank communication as a preeminent concern, it remains deficient in process and content, even when the illness requires weeks of critical care. Strategies are available to improve symptom management and communication about appropriate goals of care. For the CCI, whose risks of death, disability, and suffering are so high, it is essential that excellent palliative care be provided along with restorative treatment in an integrated way.

Symptom assessment and management

This article reviews how to assess and manage several symptoms commonly encountered by neurologists who care for patients with advanced illness. Scientifically validated guidelines are reviewed and practical advice is offered on how to manage pain, nausea and vomiting, dyspnea, and respiratory secretions at the end of life. The role of the neurologist as a provider of end of life care is discussed including suggestions for communicating with patients and families. This article concludes with a review of when sedation may be offered within the purview of good palliative care to patients who are imminently dying.

Definition of and mechanism for opioid-induced sedation

Although sedation is acknowledged to be one of the most common side effects of opioid analgesics, the mechanisms and characteristics of this phenomenon remain elusive, and research in this area is extremely limited. This report integrates research findings on the mechanism of action of opioids with research findings on the phenomenon of consciousness to develop a model of how opioids may act in the central nervous system to produce sedation. Based on this integration, a definition of opioid-induced sedation is proposed to encourage dialogue and research on this perplexing and clinically significant phenomenon.

Depression with psychomotor retardation: diagnostic challenges and the use of psychostimulants

A patient with advanced pancreatic cancer is presented to demonstrate the clinical challenge of diagnosing depression in palliative care. The conundrum related to the relative roles of somatic and psychological symptoms in screening or diagnosing depression in these patients is illustrated and discussed. There is no clear consensus on how to apply diagnostic criteria for diagnosing depression in these patients. Although an approach that focuses on the psychological symptoms is often suggested, it appears that somatic criteria cannot be entirely excluded. The case also highlights the use of methylphenidate to treat palliative care patients. As compared to traditional antidepressants that may take as long as 6-8 weeks to have a full effect, they offer the advantage of onset of action within a few days. This is especially helpful in patients with limited life expectancies. They appear to be particularly advantageous where psychomotor retardation is a main feature of the depression. The patient discussed demonstrated an observed and self-reported improvement of mood and psychomotor retardation following the initiation of psychostimulant treatment. Larger, controlled trials, using specified criteria to diagnose depression, are warranted to elucidate the role of psychostimulants in treating depression in palliative care patients.

Pain assessment and management

Assessment and management of pain is crucial to the success of any program of care for dying patients and their families. With appropriate assessment and management, often using home health or hospice teams, pain can be controlled in more than 90% of patients. This article focuses on the symptomatic care of patients who are dying. The legal and regulatory issues that may inhibit delivery of adequate opioid therapy are also reviewed.

Methylphenidate: its pharmacology and uses

Methylphenidate is a commonly used medication in the United States. This central nervous system stimulant has a mechanism of action distinct from that of amphetamine. The Food and Drug Administration has approved methylphenidate for the treatment of attention-deficit/hyperactivity disorder and narcolepsy. Treatment with methylphenidate has been advocated in patients with traumatic brain injury and stroke, cancer patients, and those with human immunodeficiency virus infection. Placebo-controlled trials have documented its efficacy as an adjunctive agent in the treatment of depression and pain. This article reviews the current understanding of the mechanism of action and efficacy of methylphenidate in various clinical conditions.

The management of pain in sickle cell disease

The pain of vaso-occlusive crisis in patients with sickle cell disease is excruciating, incapacitating, and sometimes refractory to even the most advanced analgesic treatments. A comprehensive, multimodal approach to therapy that includes education, cognitive therapies, anti-inflammatory drugs, opioids, and psychostimulant adjuvant drugs has been presented. Until a cure for the underlying disease is found, these are the best approaches available. The authors hope that future research will find even better modalities of analgesic care.

Advances in pain management for older adult patients

Management of pain is crucial to the success of any program of care and support for dying patients and their families. Pain can be controlled in more than 90% of older adults. Components of an effective program include comprehensive, repeated pain assessment; detection and treatment of complicating medical and psychological disorders (e.g., delirium); spiritual concerns; and the judicious use of nonpharmacologic and pharmacologic therapies, radiation, and radiopharmaceuticals. Strategies that enable clinicians to prevent and treat the expected complications of nonsteroidal anti-inflammatory and opioid therapies are reviewed. Strategies to change opioid agents or routes to minimize opioid-induced side effects and to provide effective pain relief as death nears are presented.

The role of dopamine in the nucleus accumbens in analgesia

Opioid and psychostimulant drugs have long been used for the relief of chronic pain in the clinical situation. Animal studies confirm that these drugs alleviate persistent or tonic pain. Little is known, however, about the neural systems underlying the suppression of tonic pain except that they are different from those mediating the suppression of phasic (i.e., sharp and short-lasting) pain. Although spinal and brainstem-descending pain suppression mechanisms play a role in mediating the inhibition of tonic pain, it appears that this response is additionally mediated by the activation of mechanisms lying rostral to the brainstem. Recent studies suggest that the activation of mesolimbic dopamine (DA) neurons, arising from the cell bodies of the ventral tegmental area (VTA) and projecting to the nucleus accumbens (NAcc), plays an important role in mediating the suppression of tonic pain. Other studies suggest that this pain-suppression system involving the activation of mesolimbic DA neurons is naturally triggered by exposure to stress, through the endogenous release of opioids and substance P (SP) in the midbrain.

Management of pain and spinal cord compression in patients with advanced cancer. ACP-ASIM End-of-life Care Consensus Panel. American College of Physicians-American Society of Internal Medicine

General internists often care for patients with advanced cancer. These patients have substantial morbidity caused by moderate to severe pain and by spinal cord compression. With appropriate multidisciplinary care, pain can be controlled in 90% of patients who have advanced malignant conditions, and 90% of ambulatory patients with spinal cord compression can remain ambulatory. Guidelines have been developed for assessing and managing patients with these problems, but implementing the guidelines can be problematic for physicians who infrequently need to use them. This paper traces the last year of life of Mr. Simmons, a hypothetical patient who is dying of refractory prostate cancer. Mr. Simmons and his family interact with professionals from various disciplines during this year. Advance care planning is completed and activated. Practical suggestions are offered for assessment and treatment of all aspects of his pain, including its physical, psychological, social, and spiritual dimensions. The methods of pain relief used or discussed include nonpharmacologic techniques, nonopioid analgesics, opioids, adjuvant medications, radiation therapy, and radiopharmaceutical agents. Overcoming resistance to taking opioids; initiating, titrating, and changing opioid routes and agents; and preventing or relieving the side effects they induce are also covered. Data on assessment and treatment of spinal cord compression are reviewed. Physicians can use the techniques described to more readily implement existing guidelines and provide comfort and optimize quality of life for patients with advanced cancer.

Psychostimulant drugs potentiate morphine analgesia in the formalin test

Recent research has shown that the psychostimulant drug dextroamphetamine can increase the analgesia produced by opioids. Despite the strong, positive results in human clinical subjects and in animals, this combination is rarely used in clinical practice. The purpose of this paper is to investigate whether the psychostimulant drug methylphenidate (MP) can potentiate morphine analgesia in the rat formalin test, and to compare its effectiveness to that of dextroamphetamine (AMP). The formalin test was used because its long-lasting pain of moderate intensity resembles human clinical pain. Two different drug administration times were used to observe whether the early phase of the formalin response would be differentially affected by the drugs. At Drug Administration Time 1, rats received morphine 30 min prior to the formalin injection (-30 min) and MP or AMP 20 min prior to the formalin injection (-20 min). At Drug Administration Time 2, rats received morphine 10 min prior to the formalin injection (-10 min) and MP or AMP immediately prior to the formalin injection (0 min). All drugs were given subcutaneously. The results indicate that low doses of MP or AMP potentiate the analgesic effects of morphine. The clinical value of these drug combinations merits further investigation in animals and in humans.