Management of chronic pain. Part I

Tramadol Extended-Release for the Management of Pain due to Osteoarthritis

Current knowledge on pathogenesis of osteoarticular pain, as well as the consequent several, especially on the gastrointestinal, renal, and cardiovascular systems, side effects of NSAIDs, makes it difficult to perform an optimal management of this mixed typology of pain. This is especially observable in elderly patients, the most frequently affected by osteoarthritis (OA). Tramadol is an analgesic drug, the action of which has a twofold action. It has a weak affinity to mu opioid receptors and, at the same time, can result in inhibition of the reuptake of noradrenaline and serotonin in nociceptorial descending inhibitory control system. These two mechanisms, "opioidergic" and "nonopioidergic," are the grounds for contrasting certain types of pain that are generally less responsive to opioids, such as neuropathic pain or mixed OA pain. The extended-release formulation of tramadol has good efficacy and tolerability and acts through a dosing schedule that allows a high level of patients compliance to therapies with a good recovery outcome for the patients' functional status.

The role of venlafaxine and duloxetine in the treatment of depression with decremental changes in somatic symptoms of pain, chronic pain, and the pharmacokinetics and clinical considerations of duloxetine pharmacotherapy

Chronic pain is among the most common conditions to initiate medical care; 40% of patients victimized by chronic pain are not under the supervision of a physician, and about 70% of patients with severe pain are receiving pain medical care. About dollar 100 billion is an annual estimated cost representing loss of productivity, increased medical costs, and income loss. Major depressive disorder is not infrequently encountered in daily clinical practice often presenting with somatic complaints that include varieties of pain, and these may be so prominent as to direct the treatment to the somatic complaint evaluation to the exclusion of underlying psychopathology. Anxiety disorders and other psychiatric disorders may also present with such a somatization evaluation focus. Serotonin noradrenergic reuptake inhibitors (SNRIs), ie, venlafaxine and duloxetine, offer benefits over tricyclic antidepressants and serotonin reuptake inhibitors. Years of experience with venlafaxine representing a first-line pharmacotherapy for depression and anxiety have benefited patients presenting with somatic symptoms with a robust onset. A more rapid achievement by venlafaxine of remission and a high-quality pharmacokinetic and pharmacodynamic profile lead to patient compliance and facilitate both fewer relapses and recurrences. Duloxetine is broadly discussed, revealing pharmacokinetic, pharmacodynamic, adverse/side effects, cautions with requisite patient-specific selection, and laboratory monitoring. The management of somatic pain complaints of physical and psychiatric origin is discussed.

A Clinical and Pharmacologic Review of Skeletal Muscle Relaxants for Musculoskeletal Conditions

Muscle strains and other musculoskeletal disorders (MSDs) are a leading cause of work absenteeism. Muscle pain, spasm, swelling, and inflammation are symptomatic of strains. The precise relationship between musculoskeletal pain and spasm is not well understood. The dictum that pain induces spasm, which causes more pain, is not substantiated by critical analysis. The painful muscle may not show EMG activity, and when there is, the timing and intensity often do not correlate with the pain. Clinical and physiologic studies show that pain tends to inhibit rather than facilitate reflex contractile activity. The decision to treat and choice of therapy are largely dictated by the duration, severity of symptoms, and degree of dysfunction. Trigger point injections are sometimes used with excellent results in the treatment of muscle spasm in myofacial pain and low-back pain. NSAIDs are used with much greater frequency than oral skeletal muscle relaxants (SMRs) or opioids in the treatment of acute MSDs. Unfortunately, remarkably little sound science guides the choice of drug for the treatment of acute, uncomplicated MSDs, and the evaluation of efficacy of one agent over another is complicated by numerous factors. Only a limited number of high-quality, randomized, controlled trials (RCTs) provide evidence of the effectiveness of NSAIDs or SMRs in the treatment of acute, uncomplicated MSDs. The quality of design, execution, and reporting of trials for the treatment of MSDs needs to be improved. The combination of an SMR and an NSAID or COX-2 inhibitor or the combination of SMR and tramadol/acetaminophen is superior to single agents alone.

Focus on the COX-1 and COX-2 agents: renal events of nonsteroidal and anti-inflammatory drugs-NSAIDs

This article will focus upon some of the cautions used in the process of prescribing NSAIDs with a focus upon renal events, pharmacokinetics of COX-2 agents, and phytopharmaceuticals that present co-prescribing hematologic challenges. Prescribing any pharmacotherapeutic agent presents the clinician with the cognitive challenge between providing a therapeutic balance weighing potential benefits to be achieved through prescribing against the potential liabilities of pharmacokinetic and pharmacodynamic iatrogenic events, and drug interactions. The following information is presented as a brief overview of the familiar arachidonic acid cascade followed by the renal events reported with non-COX-2-specific NSAIDs. The pharmacokinetics of the three currently available COX-2 NSAIDs are presented. Patient-specific risk assessments for renal function/dysfunction should be considered prior to or concurrent with initiation of any NSAID therapy coupled with periodic renal monitoring during treatment of those with patient risk factors. Phytopharmaceuticals, supplements, and over-the-counter agents should be discussed with the patient following patient disclosure of use and not omitted by the patient during presentation of their medication consumption with utilization history to their respective healthcare professionals.

Efficacy of venlafaxine for the long term treatment of chronic pain with associated major depressive disorder

BACKGROUND

This was an open-label, single-center study of the long-term efficacy and effectiveness of venlafaxine extended release (XR) in the treatment of chronic pain and depression in outpatients. All patients have been diagnosed with major depressive disorder (MDD) of various types, with or without chronic pain, and had previously failed treatment with either tricyclic antidepressants (TCAs) or selective serotonin reuptake inhibitors (SSRIs).

METHODS

Efficacy of treatment was determined using the 21-item Hamilton Rating Scale for Depression (HAMD-21), the Visual Analogue Scale (VAS) for the evaluation of pain, and a 12-item quality of life scale (QOL). Patients were treated in an unblended open trial for 1 year with 150 mg or more of venlafaxine XR once daily.

RESULTS

After 1 year of treatment, 21-item Hamilton Rating Scale for Depression, Visual Analogue Scale, and quality of life scores were significantly improved from permanent baseline scores.

CONCLUSION

These data show long-term efficacy and effectiveness of venlafaxine XR, a serotonin (5-HT) and norepinephrine (NE) and dopamine (DA) reuptake inhibitor antidepressant agent, having analgesic properties.

Identifying physician-recognized depression from administrative data: consequences for quality measurement

BACKGROUND

Multiple factors limit identification of patients with depression from administrative data. However, administrative data drives many quality measurement systems, including the Health Plan Employer Data and Information Set (HEDIS).

METHODS

We investigated two algorithms for identification of physician-recognized depression. The study sample was drawn from primary care physician member panels of a large managed care organization. All members were continuously enrolled between January 1 and December 31, 1997. Algorithm 1 required at least two criteria in any combination: (1) an outpatient diagnosis of depression or (2) a pharmacy claim for an antidepressant Algorithm 2 included the same criteria as algorithm 1, but required a diagnosis of depression for all patients. With algorithm 1, we identified the medical records of a stratified, random subset of patients with and without depression (n = 465). We also identified patients of primary care physicians with a minimum of 10 depressed members by algorithm 1 (n = 32,819) and algorithm 2 (n = 6,837).

RESULTS

The sensitivity, specificity, and positive predictive values were: Algorithm 1: 95 percent, 65 percent, 49 percent; Algorithm 2: 52 percent, 88 percent, 60 percent. Compared to algorithm 1, profiles from algorithm 2 revealed higher rates of follow-up visits (43 percent, 55 percent) and appropriate antidepressant dosage acutely (82 percent, 90 percent) and chronically (83 percent, 91 percent) (p < 0.05 for all).

CONCLUSIONS

Both algorithms had high false positive rates. Denominator construction (algorithm 1 versus 2) contributed significantly to variability in measured quality. Our findings raise concern about interpreting depression quality reports based upon administrative data.

Tender points as predictors of distress and the pharmacologic management of fibromyalgia syndrome

The object of this study was to determine the association between tender point pain ratings, tender point counts and distress in people with fibromyalgia and to review the pharmacotherapy of fibromyalgia. Demographic, psychosocial, and health status information was collected from 316 health maintenance organization members with fibromyalgia. A manual tender point exam was conducted. Tender point counts predicted 3.0%, and tender point severity ratings predicted 8.3%, of the variance in distress. Little difference was found between the variance predicted for physical versus psychologic distress. A principal components analysis of all measures produced four distinct factors: global-physical functioning, tender points, psychologic, and physical. Tender point pain ratings and counts predicted a small but significant amount of variance in distress. In addition, FMS involves at least four rather distinct factors, one of which is related to tender points. Pharmacotherapeutic management is provided on a patient-specific basis including pharmacokinetics, pharmacodynamic, pathophysiologic, and psychosocial needs designed and modulated for each individual patient.

Benefit-Risk Assessment of Transdermal Fentanyl for the Treatment of Chronic Pain

Transdermal fentanyl is effective and well tolerated for the treatment of chronic pain caused by malignancy and non-malignant conditions when administered according to the manufacturer's recommendations. Compared with oral opioids, the advantages of transdermal fentanyl include a lower incidence and impact of adverse effects (constipation, nausea and vomiting, and daytime drowsiness), a higher degree of patient satisfaction, improved quality of life, improved convenience and compliance resulting from administration every 72 hours, and decreased use of rescue medication. Transdermal fentanyl is a useful analgesic for cancer patients who are unable to swallow or have gastrointestinal problems. Transdermal fentanyl forms a depot within the upper skin layers before entering the microcirculation. Therapeutic blood levels are attained 12-16 hours after patch application and decrease slowly with a half-life of 16-22 hours following removal. Patients with chronic pain should be titrated to adequate relief with short-acting oral or parenteral opioids prior to the initiation of transdermal fentanyl in order to prevent exacerbations of pain or opioid-related adverse effects. Transdermal fentanyl can then be initiated based on the 24-hour opioid requirement once adequate analgesia has been achieved. The prolonged elimination of transdermal fentanyl can become problematic if patients develop opioid-related adverse effects, especially hypoventilation. Adverse effects do not improve immediately after patch removal and may take many hours to resolve. Patients who experience opioid-related toxicity associated with respiratory depression should be treated immediately with an opioid antagonist such as naloxone and closely monitored for at least 24 hours. Because of the short half-life of naloxone, sequential doses or a continuous infusion of the opioid antagonist may be necessary. Transdermal fentanyl should be administered cautiously to patients with pre-existing conditions such as emphysema that may predispose them to the development of hypoventilation. Transdermal fentanyl is indicated only for patients who require continuous opioid administration for the treatment of chronic pain that cannot be managed with other medications. It is contraindicated in the management of acute and postoperative pain, as pain may decrease more rapidly in these circumstances than fentanyl blood levels can be adjusted, leading to the development of life-threatening hypoventilation. Cognitive and physical impairments such as confusion and abnormal co-ordination can occur with transdermal fentanyl. Therefore, patients should be instructed to refrain from driving or operating machinery immediately following the initiation of transdermal fentanyl, or after any dosage increase. Patients may resume such activities once the absence of these potential adverse effects is documented.

Interdisciplinary treatment of chronic pain

Interdisciplinary treatment care must address more than the physical pathology. Chronic pain comprises a range of interdependent variables including biologic, cognitive, affective, behavioral, and social factors. This article discusses these psychosocial issues, as well as the four levels of pain management programs, and the characteristics and goals of interdisciplinary treatment. Finally, recent clinical studies demonstrating the efficacy and cost benefits of interdisciplinary pain management programs are reviewed.

Long-acting opioids for chronic pain: pharmacotherapeutic opportunities to enhance compliance, quality of life, and analgesia

Effective management of chronic pain has become an increasingly critical issue in health care. Opioid agonists are among the most effective analgesics available for reducing pain perception; however, their chronic use is controversial. This is primarily due to regulatory barriers, misunderstandings about pain management among primary caregivers, fear of adverse side effects, and misconceptions about the potential risks of addiction. Short-acting opioids provide effective analgesia for acute pain but should be avoided as primary analgesics for chronic pain management. Long-acting opioids have greater utility than short-acting opioids in treating chronic pain in patients with consistent pain levels. Results of studies show that improved quality of life is directly related to the use of long-acting opioids in patients with chronic pain of both cancer and noncancer etiology. Short-acting opioids may be used during the initial dose titration period of long-acting formulations and as rescue medication for episodes of breakthrough pain. Clinical experience reveals that selection of an effective pain regimen for the patient with chronic pain, combined with aggressive management of side effects, leads to improved overall functioning and quality of life.

The use of mirtazapine in a patient with chronic pain

Antidepressant drugs that act on serotonin and noradrenergic systems may be analgesic. The newer antidepressant mirtazapine (Remeron) has activity on noradrenergic and serotonergic transmission and is approved for the treatment of a Major Depressive Disorder. This paper describes a case that suggests that mirtazapine may also be useful in the treatment of chronic pain.

Review of the results from clinical studies on the efficacy, safety and tolerability of mirtazapine for the treatment of patients with major depression

Mirtazapine is a presynaptic alpha-2 antagonist that has dual action by increasing noradrenergic and serotonergic neurotransmission. The enhancement of serotonergic neurotransmission is specifically mediated via 5-HT1 receptors because mirtazapine is a postsynaptic serotonergic 5-HT2 and 5-HT3 antagonist. In addition, mirtazapine has only a weak affinity for 5-HT1 receptors and has very weak muscarinic anticholinergic and histamine (H1) antagonist properties. As a consequence of its unique pharmacodynamic properties, mirtazapine is an effective, safe and well-tolerated addition to the antidepressant armamentarium. Mirtazapine is well absorbed from the gastrointestinal tract following oral administration, and it is extensively metabolized in the liver to four metabolites via demethylation and hydroxylation, followed by glucuronide conjugation. The unconjugated desmethyl metabolite is pharmacologically less active than the parent compound. Mirtazapine lacks auto-induction of hepatic isoenzymes. Although mirtazapine is a substrate of P450 isoenzymes 1A2, 2D6 and 3A4, in vitro studies show that it is not a potent inhibitor or inducer of any of these enzymes. Mirtazapine has been evaluated in a worldwide clinical development program involving approximately 4500 patients. Controlled clinical trials involving almost 2800 mirtazapine-treated patients have demonstrated the compound to be effective for the treatment of moderate-to-serve major depression. Mirtazapine was consistently superior to placebo, and equivalent in efficacy to the tricyclic antidepressants amitriptyline, doxepin and clomipramine, but with an improved tolerability profile. Mirtazapine has shown a rapid onset of action in patients with predominantly severe depressive illness in a comparative study against fluoxetine. Mirtazapine has a unique tolerability profile, since the specific postsynaptic 5-HT2 and 5-HT3 receptor blockade of mirtazapine provides early antidepressant effects without causing unwanted serotonin-related side-effects. Transient somnolence, hyperphagia and weight gain are the most commonly reported adverse events, which may be attributed to the antihistaminic (H1) activity of mirtazapine at low doses. Somnolence, the most commonly reported side-effect, appears to be less frequent at higher dosages. Mirtazapine also demonstrates important anxiolytic and sleep-improving effects, which may be related to its pharmacodynamic properties. In addition, mirtazapine does not appear to be associated with sexual dysfunction. Mirtazapine has shown no significant cardiovascular adverse effects at multiples of 7 to 22 times the maximum recommended dose. Mirtazapine is a unique addition to the antidepressant armamentarium as first-line therapy in patients with major depression and symptoms of anxiety/agitation or anxiety/somatization or complaints of insomnia and as a useful alternative in depressed patients who do not adequately respond to or are intolerant of tricyclic antidepressants or serotonin-specific reuptake inhibitors.