A double-blind comparison in general practice of a combination tablet containing orphenadrine citrate and paracetamol ('Norgesic') with paracetamol alone

Pharmacotherapy for Spine-Related Pain in Older Adults

As the population ages, spine-related pain is increasingly common in older adults. While medications play an important role in pain management, their use has limitations in geriatric patients due to reduced liver and renal function, comorbid medical problems, and polypharmacy. This review will assess the evidence basis for medications used for spine-related pain in older adults, with a focus on drug metabolism and adverse drug reactions. A PubMed/OVID search crossing common spine, neck, and back pain terms with key words for older adults and geriatrics was combined with common drug classes and common drug names and limited to clinical trials and age over 65 years. The results were then reviewed with identification of commonly used drugs and drug categories: nonsteroidal anti-inflammatories (NSAIDs), acetaminophen, corticosteroids, gabapentin and pregabalin, antispastic and antispasmodic muscle relaxants, tricyclic antidepressants (TCAs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tramadol, and opioids. Collectively, 138 double-blind, placebo-controlled trials were the focus of the review. The review found a variable contribution of high-quality studies examining the efficacy of medications for spine pain primarily in the geriatric population. There was strong evidence for NSAID use with adjustments for gastrointestinal and renal risk factors. Gabapentin and pregabalin had mixed evidence for neuropathic pain. SNRIs had good evidence for neuropathic pain and a more favorable safety profile than TCAs. Tramadol had some evidence in older patients, but more so in persons aged < 65 years. Rational therapeutic choices based on geriatric spine pain diagnosis are helpful, such as NSAIDs and acetaminophen for arthritic and myofascial-based pain, gabapentinoids or duloxetine for neuropathic and radicular pain, antispastic agents for myofascial-based pain, and combination therapy for mixed etiologies. Tramadol can be well tolerated in older patients, but has risks of cognitive and classic opioid side effects. Otherwise, opioids are typically avoided in the treatment of spine-related pain in older adults due to their morbidity and mortality risk and are reserved for refractory severe pain. Whenever possible, beneficial geriatric spine pain pharmacotherapy should employ the lowest therapeutic doses with consideration of polypharmacy, potentially decreased renal and hepatic metabolism, and co-morbid medical disorders.

Clinical Response of Nuberol Forte® for Pain Management With Musculoskeletal Conditions in Routine Pakistani Practice (NFORTE-EFFECT)

Background

Musculoskeletal pain is the most common complaint presented to the health practitioner. It is well-known that untreated or under-treated pain can have a significant negative impact on an individual’s quality of life (QoL).

Objectives

The current study aimed to assess the clinical response of Nuberol Forte® (paracetamol 650 mg + orphenadrine 50 mg) to musculoskeletal pain in routine Pakistani practice and its impact on improving the patient’s QoL.

Methods

A prospective, observational multicenter study (NFORT-EFFECT: Safety & Efficacy of Nuberol Forte in Pain Management). Three hundred ninety-nine patients with known prescreened musculoskeletal pain were recruited from 10 major healthcare facilities across six (6) major cities of Pakistan, as per the inclusion/exclusion criteria. After the baseline visit (Visit 1), the patients were followed up one to two weeks (Visit 2) after the treatment as per the physician's discretion. Data were collected using the Case Report Form (CRF) designed for the study, and adverse events (AEs) were also monitored to assess drug safety. Pain intensity was assessed through a visual analog scale (VAS), and QoL was assessed using the Muscle and Joint Measure (MJM) scale.

Results

Out of 399 enrolled patients, 49.4% were males and 50.6% were females with a mean age of 47.24 ± 14.20 years. Most patients were presented with knee osteoarthritis (OA), i.e., 148 (38%), followed by backache 70 (18.2%). A significant reduction in the mean pain score was observed after treatment with the combination of paracetamol and orphenadrine (p<0.05). Furthermore, an overall improvement in the patient’s QoL was also observed. During the study, only 10 patients reported mild adverse events (AEs), namely, dryness of the mouth, dizziness, gastric irritation, tachycardia, restlessness, etc.

Conclusion

The combination of paracetamol and orphenadrine (Nuberol Forte) exhibited effective pain management among patients with musculoskeletal conditions and improved their QoL.

Development of a capillary electrophoresis method for the determination of orphenadrine citrate in tablets in the presence of paracetamol

A validated method using capillary electrophoresis was developed, for the determination of orphenadrine citrate in its tablet formulations, in the presence of paracetamol. The method employs a running buffer of 30 mM pentane sulfonate sodium, dissolved in 20 mM MOPS buffer pH 7.7. Samples were injected using hydrodynamic sample injection mode (25 mbar, for 25 s), using positive polarity of 25 kV, at a constant temperature of 30 °C. Samples of orphenadrine citrate alone or in mixture solutions with paracetamol were exposed to various degradation conditions, and were electrophoresed using the recommended condition. The method was found to be specific, linear (r (2) = 0.994), precise, accurate, and robust, with an LOQ of 0.02 mg/mL. The proposed method was successfully applied for measurement of the percentage per label of orphenadrine citrate in commercially available tablets.

Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions: a systematic review

Skeletal muscle relaxants are a heterogeneous group of medications used to treat two different types of underlying conditions: spasticity from upper motor neuron syndromes and muscular pain or spasms from peripheral musculoskeletal conditions. Although widely used for these indications, there appear to be gaps in our understanding of the comparative efficacy and safety of different skeletal muscle relaxants. This systematic review summarizes and assesses the evidence for the comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions. Randomized trials (for comparative efficacy and adverse events) and observational studies (for adverse events only) that included oral medications classified as skeletal muscle relaxants by the FDA were sought using electronic databases, reference lists, and pharmaceutical company submissions. Searches were performed through January 2003. The validity of each included study was assessed using a data abstraction form and predefined criteria. An overall grade was allocated for the body of evidence for each key question. A total of 101 randomized trials were included in this review. No randomized trial was rated good quality, and there was little evidence of rigorous adverse event assessment in included trials or observational studies. There is fair evidence that baclofen, tizanidine, and dantrolene are effective compared to placebo in patients with spasticity (primarily multiple sclerosis). There is fair evidence that baclofen and tizanidine are roughly equivalent for efficacy in patients with spasticity, but insufficient evidence to determine the efficacy of dantrolene compared to baclofen or tizanidine. There is fair evidence that although the overall rate of adverse effects between tizanidine and baclofen is similar, tizanidine is associated with more dry mouth and baclofen with more weakness. There is fair evidence that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions (primarily acute back or neck pain). Cyclobenzaprine has been evaluated in the most clinical trials and has consistently been found to be effective. There is very limited or inconsistent data regarding the effectiveness of metaxalone, methocarbamol, chlorzoxazone, baclofen, or dantrolene compared to placebo in patients with musculoskeletal conditions. There is insufficient evidence to determine the relative efficacy or safety of cyclobenzaprine, carisoprodol, orphenadrine, tizanidine, metaxalone, methocarbamol, and chlorzoxazone. Dantrolene, and to a lesser degree chlorzoxazone, have been associated with rare serious hepatotoxicity.

Muscle relaxants for nonspecific low back pain: a systematic review within the framework of the cochrane collaboration

STUDY DESIGN

A systematic review of randomized and/or double-blinded controlled trials.

SUMMARY OF BACKGROUND DATA

The use of muscle relaxants in the management of nonspecific low back pain is controversial. It is not clear if they are effective, and concerns have been raised about the potential adverse effects involved.

OBJECTIVES

The aim of this review was to determine if muscle relaxants are effective in the treatment of nonspecific low back pain.

METHODS

A computer-assisted search of the Cochrane Library (Issue 2, 2002), MEDLINE (1966 up to October 2001), and EMBASE (1988 up to October 2001) was carried out. These databases were searched using the algorithm recommended by the Cochrane Back Review Group. References cited in the identified articles and other relevant literature were screened. Randomized and/or double-blinded controlled trials, involving patients diagnosed with nonspecific low back pain, treated with muscle relaxants as monotherapy or in combination with other therapeutic methods, were included for review. Two reviewers independently carried out the methodologic quality assessment and data extraction of the trials. The analysis comprised not only a quantitative analysis (statistical pooling) but also a qualitative analysis ("best evidence synthesis"). This involved the appraisal of the strength of evidence for various conclusions using a rating system based on the quality and outcomes of the studies included. Evidence was classified as "strong," "moderate," "limited," "conflicting," or "no" evidence.

RESULTS

Thirty trials met the inclusion criteria. Twenty-three trials (77%) were of high quality; 24 trials (80%) were on acute low back pain. Four trials studied benzodiazepines, 11 nonbenzodiazepines, and 2 antispasticity muscle relaxants in comparison with placebo. Results showed that there is strong evidence that any of these muscle relaxants are more effective than placebo for patients with acute low back pain on short-term pain relief. The pooled relative risk for nonbenzodiazepines versus placebo after 2 to 4 days was 0.80 (95% confidence interval: 0.71 to 0.89) for pain relief and 0.49 (95% confidence interval: 0.25 to 0.95) for global efficacy. Adverse events, however, with a relative risk of 1.50 (95% confidence interval: 1.14 to 1.98) were significantly more prevalent in patients receiving muscle relaxants and especially the central nervous system adverse effects (relative risk 2.04; 95% confidence interval: 1.23 to 3.37). The various muscle relaxants were found to be similar in performance.

CONCLUSIONS

Muscle relaxants are effective in the management of nonspecific low back pain, but the adverse effects require that they be used with caution. Trials are needed that evaluate if muscle relaxants are more effective than analgesics or nonsteroidal anti-inflammatory drugs.

Muscle relaxants for non-specific low back pain

BACKGROUND

The use of muscle relaxants in the management of non-specific low back pain is controversial. It is not clear if they are effective, and concerns have been raised about the potential adverse effects involved.

OBJECTIVES

The aim of this review was to determine if muscle relaxants are effective in the treatment of non-specific low back pain.

SEARCH STRATEGY

A computer-assisted search of the Cochrane Library (Issue 2, 2002), MEDLINE (1966 up to October 2001) and EMBASE (1988 up to October 2001) was carried out. These databases were searched using the algorithm recommended by the Cochrane Back Review Group. References cited in the identified articles and other relevant literature were screened.

SELECTION CRITERIA

Randomised and/or double-blinded controlled trials, involving patients diagnosed with non-specific low back pain, treated with muscle relaxants as monotherapy or in combination with other therapeutic modalities, were included for review.

DATA COLLECTION AND ANALYSIS

Two reviewers independently carried out the methodological quality assessment and data extraction of the trials. The analysis comprised not only a quantitative analysis (statistical pooling) but also a qualitative analysis ("best evidence synthesis"). This involved the appraisal of the strength of evidence for various conclusions using a rating system based on the quality and outcomes of the studies included. Evidence was classified as "strong", "moderate", "limited", "conflicting" or "no" evidence.

MAIN RESULTS

Thirty trials met the inclusion criteria. Twenty-three trials (77%) were of high quality, 24 trials (80%) were on acute low back pain. Four trials studied benzodiazepines, 11 non-benzodiazepines and two antispasticity muscle relaxants in comparison with placebo. Results showed that there is strong evidence that any of these muscle relaxants are more effective than placebo for patients with acute LBP on short-term pain relief. The pooled RR for non-benzodiazepines versus placebo after two to four days was 0.80 [95% CI; 0.71 to 0.89] for pain relief and 0.49 [95% CI; 0.25 to 0.95] for global efficacy. Adverse events, however, with a relative risk of 1.50 [95% CI; 1.14 to 1.98] were significantly more prevalent in patients receiving muscle relaxants and especially the central nervous system adverse effects (RR 2.04; 95% CI; 1.23 to 3.37). The various muscle relaxants were found to be similar in performance.

REVIEWER'S CONCLUSIONS

Muscle relaxants are effective in the management of non-specific low back pain, but the adverse effects require that they be used with caution. Trials are needed that evaluate if muscle relaxants are more effective than analgesics or non-steroidal anti-inflammatory drugs.

The use of analgesics in the management of pain in rheumatic diseases

Pain is the most common complaint of patients who see rheumatologists. In this article, the current treatment options for pain are reviewed; these include acetaminophen, nonsteroidal anti-inflammatory drugs, new specific cyclooxygenase-2 inhibitors, opioid analgesics, centrally acting muscle relaxants, antidepressants, and topical analgesics and counterirritants. The doses of medication and known adverse effects of these medications are highlighted.

Centrally acting skeletal muscle relaxants and associated drugs

A review of available studies supports a role for muscle relaxants in the treatment of painful musculoskeletal disorders. The utility of these drugs is limited by sedation and other side effects, as well as by the potential for abuse and dependency. Other drugs can also be used in the treatment of muscle spasm, specifically diazepam, baclofen, dantrolene sodium, and quinine sulfate. The pharmacology of the muscle relaxants and these other agents is discussed and practical suggestions for use are offered.

Acute low back pain and economics of therapy: the iterative loop approach

We use the measurement iterative loop as a conceptual framework to examine the economics of common therapies for acute non-specific low back pain. The measurement iterative loop systematically assesses the interlocking facets of an illness from the community health perspective, including quantifying burden of illness, etiology, assessment of therapeutic effectiveness, and economic evaluation of therapies. The iterative loop reveals that: (1) burden of illness, although known to be substantial, is so far inaccurately measured, (2) little is known about such factors as provider and patient compliance; and (3) the economics of therapy can guide us in this time of clinical uncertainty when no therapy appears clearly superior. For therapies with at least some support from randomized controlled trials, bedrest appears to be economically superior. Besides burden of illness, compliance, and current therapies, future research should address such "therapeutic" options as early return to work and patient self-management.

Clinical and pharmacological review of the efficacy of orphenadrine and its combination with paracetamol in painful conditions

Orphenadrine citrate, a monomethylated derivative of diphenhydramine, has been used as a muscle relaxant and as an analgesic both alone or as a constituent of combination products. Data on the efficacy of orphenadrine alone and in combination with paracetamol for painful conditions are evaluated in the present review. From the available animal data it is concluded that the antinociceptive effect of orphenadrine has been clearly demonstrated but data have also clearly indicated that it has muscle relaxant properties. Human placebo-controlled studies have shown some support for the view that orphenadrine on its own acts as a mild analgesic in painful conditions associated with muscle spasm. Although only a small number of well-controlled studies have been completed with the combination product of orphenadrine/paracetamol, each supports the view that the combination has superior efficacy over paracetamol alone. There is no doubt that the combination product is more efficacious than placebo.

Orphenadrine citrate increases and prolongs the antinociceptive effects of paracetamol in mice

Orphenadrine, a muscle relaxant with antinociceptive effects, was shown to increase and prolong the antinociceptive effects of paracetamol in mice. Both in the increasing temperature hot plate test and in the formalin test, a combination of the two drugs showed a significantly improved effect compared to either of the drugs alone. The time course of the effects was tested in the increasing temperature hot plate test. The group treated with the drug combination showed a prolonged effect compared to both single drug treated groups, the effect lasting longer than 120 min. for the combination and about 80 min. for the single drugs. Orphenadrine and paracetamol increased antinociception even when orphenadrine was injected 90 min. after paracetamol, which by that time did not exert antinociceptive effects by itself. Thus the combination of orphenadrine and paracetamol enhances the antinociceptive effect of either drug in mice.

Clinical efficacy of antihistaminics as analgesics

This paper reviews the clinical information on antihistaminic agents as analgesics and as analgesic adjuvants. The evidence indicates a direct analgesic effect of various antihistaminics. In clinical studies, diphenhydramine, hydroxyzine, orphenadrine and pyrilamine have been shown to produce analgesia as simple entities but chlorpheniramine has not and results with phenyltoloxamine have been equivocal when tested alone. Analgesic adjuvant effects of several antihistaminics have been reported. Clinically, orphenadrine and phenyltoloxamine have shown adjuvant effects with acetaminophen and aspirin. The mechanism of action remains speculative. The most recent trends in the classification of histamine receptors and how these receptors may interact with pain modulation are also considered.

Antinociceptive effects of orphenadrine citrate in mice

The antinociceptive effect of orphenadrine citrate, a muscle relaxant, was investigated in mice. Four different pain tests were selected to involve different noxious stimuli. Clear antinociceptive effects were found in the formalin test. The increasing temperature hot-plate test showed a biphasic dose-response relationship with slight hyperalgesia after low doses and hypoalgesia after higher doses. No significant effects of orphenadrine (0-25 mg/kg) were found in the tail flick and constant temperature hot-plate tests. The data suggest that orphenadrine may reduce, enhance or leave unaffected different types of nociceptive transmission. Orphenadrine may also possess analgesic properties in conditions not involving muscle spasm.

Effect of a combination of orphenadrine/paracetamol tablets ('Norgesic') on myalgia: a double-blind comparison with placebo in general practice

The clinical efficacy and tolerability of a combination preparation ('Norgesic') of 35 mg orphenadrine plus 450 mg paracetamol was compared with that of placebo in a controlled double-blind, parallel group, 7-day study comprising 44 patients suffering from pain due to tension of the cervical and upper thoracic musculature. The patients were allocated at random into two homogeneous groups, stratified by sex and initial pain intensity. One group received the combination, the other placebo. The dosage used was 1 tablet 3-times daily. The effect of treatment of pain was assessed daily using a visual analogue scale. Despite the low dosage used, orphenadrine/paracetamol produced statistically significant pain relief from initial levels by and from the second day of the study. Comparison between the groups showed that the analgesic efficacy of the combination was significantly superior to that of placebo from the third day of treatment. These results confirm the efficacy of a combination of orphenadrine/paracetamol in patients suffering from myalgia nuchae.