Oxcarbazepine, topiramate, zonisamide, and levetiracetam: potential use in neuropathic pain

A review about the role of additives in nerve tissue engineering: growth factors, vitamins, and drugs

Notably the integration of additives such as growth factors, vitamins, and drugs with scaffolds promoted nerve tissue engineering. This study tried to provide a concise review of all these additives that facilitates nerve regeneration. An attempt was first made to provide information on the main principle of nerve tissue engineering, and then to shed light on the effectiveness of these additives on nerve tissue engineering. Our research has shown that growth factors accelerate cell proliferation and survival, while vitamins play an effective role in cell signalling, differentiation, and tissue growth. They can also act as hormones, antioxidants, and mediators. Drugs also have an excellent and necessary effect on this process by reducing inflammation and immune responses. This review shows that growth factors were more effective than vitamins and drugs in nerve tissue engineering. Nevertheless, vitamins were the most commonly used additive in the production of nerve tissue.

Zonisamide-induced distal renal tubular acidosis and critical hypokalaemia

A woman in her 20s presented with rapidly progressive muscle weakness and a 1-month preceding history of fatigability, nausea and vomiting. She was found to have critical hypokalaemia (K+ 1.8 mmol/L), a prolonged corrected QT interval (581 ms) and a normal anion gap metabolic acidosis (pH 7.15) due to zonisamide-induced distal (type 1) renal tubular acidosis. She was admitted to the intensive care unit for potassium replacement and alkali therapy. Clinical and biochemical improvement ensued, and she was discharged after a 27-day inpatient stay.

Bilateral acute angle closure glaucoma associated with hydrochlorothiazide-induced hyponatraemia

We report a case of a 67-year-old woman presenting with bilateral acute angle closure. On investigation, she was found to have bilateral ciliary effusions and profound hyponatraemia. Her effusions resolved with the cessation of hydrochlorothiazide and normalisation of her blood sodium levels by fluid restriction. This case displays a novel association of hyponatraemia as a possible mechanism for the development of bilateral acute angle closure.

Treatment considerations in neuropathic pain

Neuropathy is a relatively common source of acute and chronic pain. Emerging evidence suggests several pathophysiological mechanisms underlying the neuropathic pain associated with various disorders. Antidepressants and anticonvulsants have largely been the mainstay of treatment. Pharmacologic treatment of neuropathy frequently requires use of multiple medications. Ideally, the selection of which medications to use should be based on targeting the multiple pathophysiologic mechanisms contributing to neuropathic pain transmission. Psychological variables may play a role in predisposing patients to chronic neuropathy after acute illness. In addition, comorbid conditions, especially depression, can complicate the presentation, clinical course, and response to treatment of patients with chronic pain. Treatment of depression may be essential to fully enlist the chronic neuropathic pain patient in comprehensive pain management and rehabilitative approaches.

Comparison of antinociceptive effect of the antiepileptic drug gabapentin to that of various dosage combinations of gabapentin with lamotrigine and topiramate in mice and rats

INTRODUCTION

Newer anticonvulsants have a neuromodulatory effect on pain perception mechanisms in a hyperexcitable and damaged nervous system.

AIM

This study was designed to study the analgesic effects of gabapentin alone and in combination with lamotrigine and topiramate in experimental pain models.

MATERIALS AND METHODS

Adult albino mice (n=490) weighing 20-30 g and rats (n=130) weighing 100-200 g were injected intraperitoneally with gabapentin, lamotrigine, and topiramate alone and in different dose combinations. The hot-plate method, tail-flick method, capsaicin-induced mechanical hyperalgesia, and formalin assay were used to assess the antinociceptive effects.

RESULTS

Of the three antiepileptic drugs, when given separately, gabapentin was more efficacious than either topiramate or lamotrigine in all the pain models. Combination of 25 mg/kg gabapentin with 25 mg/kg topiramate was more efficacious (P<.05) than 50 mg/kg gabapentin alone in the capsaicin-induced mechanical hyperalgesia test. Similarly, 50 mg/kg gabapentin with 50 mg/kg topiramate or 5 mg/kg lamotrigine was more efficacious (P<.05) than 50 or 100 mg/kg gabapentin alone in late-phase formalin-induced behaviors.

CONCLUSIONS

Combination of gabapentin with either lamotrigine or topiramate produced better results than gabapentin alone in capsaicin-induced mechanical hyperalgesia test and in late-phase formalin-induced behaviors.

Painful and involuntary multiple sclerosis

INTRODUCTION

Pain, dysphagia, respiratory problems, sexual and cardiovascular dysfunctions may occur in patients with MS.

AREAS COVERED

In the present review, we attempt to summarize the current knowledge on the impact pain, dysphagia, respiratory problems, sexual and cardiovascular dysfunctions have in patients with MS.

EXPERT OPINION

To effectively manage MS, it is essential that these symptoms are recognized as early as possible and treated by a rehabilitative multidisciplinary approach, based on proven scientific evidence.

Acute and chronic pain following craniotomy

PURPOSE OF REVIEW

The purpose of the review is to describe what is currently known about the mechanisms, incidence and risk factors for acute and chronic postcraniotomy pain. The review will also summarize the evidence supporting the prevention and management of acute and chronic postcraniotomy pain.

RECENT FINDINGS

Current studies suggest acute and chronic pain is common in patients after craniotomy. Surgical and patient factors may influence the incidence and severity of pain and a multimodal approach to acute postcraniotomy pain is recommended. Although codeine and tramadol are frequently used in the postoperative period, research suggests morphine provides superior efficacy with a good safety profile. Local anesthesia with nerve blocks has not been shown to consistently reduce acute postoperative pain, though it has recently been demonstrated to dramatically reduce the incidence of chronic pain. Despite this, little is known about the mechanisms, prevention and treatment of chronic postcraniotomy pain.

SUMMARY

Acute and chronic pain following craniotomy is frequent and underrecognized. Several surgical and patient risk factors predispose patients to pain following neurosurgery. Further research is needed to determine the mechanisms, predictors, prevention and optimal treatment of acute and chronic pain following craniotomy.

A review of the use of zonisamide in Parkinson's disease

Although zonisamide was previously only used to treat epilepsy, recently more applications have been forthcoming. Due to a good side effect profile, a lower frequency of interactions and a more comfortable posology, there are several studies regarding its uses in other pathologies such as migraine, neuropathic pain, essential tremor and various psychiatric diseases. A multicentered, randomized, double-blind, placebo-controlled study conducted in Japan suggested that zonisamide, as an add-on treatment, has efficacy in treating motor symptoms in patients with Parkinson's disease. In addition, other studies support the utility of zonisamide in other symptoms of this disease. The therapeutic doses of zonisamide for the treatment of Parkinson's disease are considerably lower than those for the treatment of epilepsy. This antiepileptic drug has been used in Japan for more than 15 years and so it is expected that it will be safe and well tolerated in patients with Parkinson's disease. However, the pharmacological mechanisms of the antiparkinsonian actions of zonisamide remain unclear and more basic investigation is warranted. The aim of this paper is to review the structure, mechanisms of action, pharmacokinetics and antiparkinsonian action of zonisamide.

Levetiracetam for managing neurologic and psychiatric disorders

PURPOSE

The role of levetiracetam in different epileptic, nonepileptic, neurologic, and psychiatric disorders is discussed.

SUMMARY

Levetiracetam, an antiepileptic drug (AED), was first approved as an adjunctive therapy for the treatment of partial epilepsy in adults. It is currently being used in the treatment of multiple seizure disorders, including generalized tonic-clonic; absence; myoclonic, especially juvenile myoclonic; Lennox-Gastaut syndrome; and refractory epilepsy in children and adults. Data are emerging on possible uses of levetiracetam outside the realm of epilepsy because of its unique mechanisms of action. There is preliminary evidence about the efficacy of levetiracetam in the treatment of different psychiatric disorders, including anxiety, panic, stress, mood and bipolar, autism, and Tourette's syndrome. The most serious adverse effects associated with levetiracetam use are behavioral in nature and might be more common in patients with a history of psychiatric and neurobehavioral problems.

CONCLUSION

Levetiracetam is an effective AED with potential benefits in other neurologic and psychiatric disorders. The benefit-risk ratio in an individual patient with a specific condition should be used to determine its optimal use. Levetiracetam's use in nonepileptic conditions is not recommended until more data become available from larger trials.

Antinociceptive effect of topiramate in models of acute pain and diabetic neuropathy in rodents

This study assesses the antinociceptive effect induced by different dosages of topiramate (TP), an anticonvulsant drug that is orally administered in models of neuropathic pain and acute pain in rats and mice, respectively. Orally administered TP (80 mg/Kg) in mice causes antinociception in the first and second phases of a formalin test, while in doses of 20 and 40 mg/Kg it was only effective in the second phase. TP (80 mg/Kg, p.o) also exhibited antinociceptive action in the hot plate test, however, it did not have an effect in the capsaicin test in mice, nor in the model of neuropathic pain in diabetic rats. The antinociceptive effect caused by TP (80 mg/Kg, p.o) in the formalin test was reversed by prior treatment with naloxone (opioid antagonist), but not with glibenclamide (antagonist of the potassium channel), ondansetron (antagonist of the serotonin 5HT3 receptor) or cyproheptadine (antagonist of the serotonin 5HT2A receptor).The data show that TP has an important antinociceptive effect in the models of nociception induced by chemical (formalin) or thermal (hot plate) stimuli, and that the opioid system plays a part in the antinociceptive effect, as shown by formalin.

Orofacial pain and neurosensory disorders and dysfunction in cancer patients

Orofacial pain and altered nerve sensation may be the initial sign of oropharyngeal or nasopharyngeal cancer. This article focuses on the most common orofacial pain conditions and neurosensory alterations that affect cancer patients, such as neuropathic pain, muscle spasm or contractures, mucositis, and increased or decreased sensory discrimination in the affected area. The various pharmacotherapeutic modalities for cancer pain management ranging from non steroidal anti-inflammatory drugs (NSAIDs) for mild pain to opioids for severe pain are discussed in detail.

Levetiracetam for the treatment of hot flashes: a phase II study

GOALS OF WORK

The objectives of this pilot trial were to assess the potential efficacy and safety of levetiracetam for the treatment of hot flashes, a major cause of morbidity among breast cancer survivors.

PATIENTS AND METHODS

Women, aged 18 years or more, with a history of breast cancer or those who wished to avoid estrogen because of a perceived increased risk of breast cancer, who were experiencing bothersome hot flashes (more than or equal to 14 times per week, for more than or equal to 1 month before study entry), were included. During the baseline week, general demographic characteristics, hot flash information, and quality of life data were obtained. At the beginning of week 2, patients were started on levetiracetam for a total of 4 weeks. Information about hot flashes, quality of life, and toxicity were collected during these 4 weeks and compared with the baseline week.

MAIN RESULTS

After treatment with levetiracetam for 4 weeks (N = 19), mean hot flash scores (frequency times mean severity) were reduced by 57%, and mean hot flash frequencies were reduced by 53%, compared to the baseline week; both these reductions were greater than what would be expected with a placebo (20-25% reduction). There were significant improvements in abnormal sweating (p = 0.004), hot flash distress (p = 0.0002), and satisfaction of hot flash control (p = 0.0001), when comparing data from the fourth week of treatment to the baseline week. Twenty-nine percent of the subjects did not complete the study because of treatment-related adverse events, with the most frequently reported side effects being somnolence, fatigue, and dizziness, usually with mild to moderate intensity.

CONCLUSION

The results of this pilot trial suggest that levetiracetam might be an effective therapy for the treatment of hot flashes. Further data are needed to test this hypothesis, evaluating the efficacy and toxicity of this agent.

Intravenous mononuclear marrow cells reverse neuropathic pain from experimental mononeuropathy

BACKGROUND

Stem cells mediate neuroprotection in a variety of nervous system injury models. In this study, we evaluated a potential role for stem cells in pain therapies. Marrow mononuclear cells containing mixed stem cell populations were used because of wide experience with these cells in experimental and clinical transplantation.

METHODS

After sciatic nerve chronic constriction injury (CCI), adult male Sprague Dawley rats were treated with freshly isolated marrow mononuclear cells (10(7) cells in 0.5 mL IV) from the same strain, or with carrier. The major end points of analysis were thermal and mechanical hypersensitivity using paw withdrawal latency (PWL) to a calibrated heat source and paw withdrawal response to von Frey filaments, evaluated by a blinded investigator.

RESULTS

Marrow transplantation did not prevent pain, and 5 days after CCI all animals were equivalently lesioned. However, 10 days after CCI, rats that received marrow transplants demonstrated paw withdrawal response and PWL patterns indicating recovery from pain, whereas untreated rats continued to have significant pain behavior patterns. For example, PWL values for marrow-treated animals were similar to baseline pre-CCI values (P = 0.54) but significantly shorter latency to withdrawal indicative of continuing pain was seen in untreated rats compared with pre-CCI values (P < 0.001).

CONCLUSIONS

These studies suggest that stem or progenitor cell-mediated therapies may be useful for the treatment of pain after nerve injury, and deserve further study to elucidate the mechanisms of analgesia.

Management of painful neuropathies

Inadequately assessed and poorly managed pain contributes both to high general medical cost and to increasing numbers of societal problems. A large determining factor of inadequate pain care is the lack of understanding about the complex nature of pain and of a rational approach to its assessment and treatment. The less than adequate assessment of neuropathic pain and its relatively poor response to typical analgesic medications are major determinants to the undertreatment of pain. Other than the important management concept of treating the underlying cause, current approaches to the treatment of pain in general, and neuropathic pain in particular, have shifted away from treatment of individual syndromes toward the identification and management of common symptoms and the mechanisms upon which such symptoms are presumed to be based. This article summarizes the features of neuropathic pain that commonly appear in most peripheral neuropathies, regardless of the mechanism of injury, and provides an approach for the selection of treatment.

Zonisamide or levetiracetam for adults with cyclic vomiting syndrome: a case series

BACKGROUND & AIMS

Management of cyclic vomiting syndrome in adults is limited by the small number of effective medications for maintenance therapy. The clinical response to treatment with 2 newer antiepileptic drugs was evaluated retrospectively to see whether they might have a prophylactic role in this syndrome.

METHODS

Outpatient records from 20 adult patients with cyclic vomiting syndrome attending a university-based practice were reviewed. Each had received zonisamide (median dose, 400 mg/d) or levetiracetam (median dose, 1000 mg/d) because tricyclic antidepressants alone were unsatisfactory as maintenance medications. Outcome was graded from chart review and directed interview; characteristics of the vomiting episodes were compared before and after initiation of antiepileptic drug therapy.

RESULTS

At least moderate clinical response was described by 15 (75.0%) subjects, and 4 of these (20.0% of the total) reported symptomatic remission during 9.5 +/- 1.8 months of follow-up. Rate of vomiting episodes decreased from 1.3 +/- 0.3 to 0.5 +/- 0.2 per month (P = .01). Tricyclic antidepressants were discontinued in 11 (61.1%) of the 18 subjects who were still taking the medications when antiepileptic drug therapy was initiated. Moderate or severe side effects were reported by 45.0%, but by switching drugs, intolerance to antiepileptic drug therapy occurred in only 1 subject.

CONCLUSIONS

Newer antiepileptic drugs, specifically zonisamide and levetiracetam, appeared beneficial as maintenance medications for nearly three fourths of adults with cyclic vomiting syndrome in this uncontrolled clinical experience. Although side effects occur in a large proportion of subjects, newer antiepileptic drugs might offer an alternative for patients who fail conventional treatment.

Nonepileptic uses of antiepileptic drugs in children and adolescents

Antiepileptic drugs are often prescribed for nonepileptic neurologic and psychiatric conditions. The United States Food and Drug Administration has approved several antiepileptic drugs for the treatment of neuropathic pain, migraine, and mania in adults. For pediatric patients, use of antiepileptic drugs for non-seizure-related purposes is supported mainly by adult studies, open-label trials, and case reports. Summarized here is the published literature for or against the use of antiepileptic drugs for neuropathic pain, migraine, movement disorders, bipolar disorder, aggressive behavior, and pervasive developmental disorders in children and adolescents. Using the American Academy of Neurology's four-tiered classification scheme for a therapeutic article and translation to a recommendation rating, there are no nonepileptic disorders for which antiepileptic drugs have been established as effective for pediatric patients. Valproate and carbamazepine are "possibly effective" in the treatment of Sydenham chorea, and valproate is "probably effective" in decreasing aggressive behavior. Carbamazepine is "probably ineffective" in the treatment of aggression, and lamotrigine is "possibly ineffective" in improving the core symptom of pervasive developmental disorders. Despite the frequent use of antiepileptic drugs in the treatment of juvenile bipolar disorder, migraine, and neuropathic pain, the data are insufficient to make recommendations regarding the efficacy of antiepileptics in these conditions in children and adolescents.

New Anticonvulsants—New Adverse Effects

Ongoing refinements in pharmacology continue to provide new medications for the treatment of seizure disorders and other neurologic conditions. The authors present the cases of two children who developed relatively uncommon adverse effects to new anticonvulsant medications, including metabolic acidosis with topiramate and hyponatremia with oxcarbazepine. In one of our two patients, intraoperative acidosis related to topiramate was noted. Appropriate investigation with documentation of normal serum lactate resulted in the exclusion of other potentially serious causes of acidosis and in the identification of topiramate as the causative agent. In our second patient, hyponatremia and status epilepticus resulted from therapy with oxcarbazepine. Prompt recognition of hyponatremia, fluid restriction, and cessation of oxcarbazepine therapy resulted in prompt correction of the hyponatremia. We review previous reports of these adverse effects with topiramate and oxcarbazepine, describe the pathophysiology of these metabolic alterations, provide treatment strategies, and make suggestions for monitoring patients during therapy with these anticonvulsant medications.

Adjunctive pharmacological management of persistent, nonmalignant pain in older individuals

Chronic or persistent pain is a common comorbidity of aging, primarily due to the relatively high frequency of pain-associated disorders in this population (e.g., inflammatory and noninflammatory musculoskeletal disease, zoster infection, diabetes, stroke, and peripheral and central neurological diseases). Acetaminophen, nonsteroidal anti-inflammatory drugs and opioids are important long-term analgesics in this age group. However, adjunctive agents are also important in the management of persistent pain in the elderly, especially neuropathic pain. Oral antiepileptic drugs, mexiletine, baclofen, tricyclic antidepressants, selective serotonin–norepinephrine dual reuptake inhibitors and intranasal/injectable calcitonin are the subjects of this review of the management of persistent, nonmalignant pain in the elderly. While some of these agents are considered narrow-spectrum analgesics (e.g., baclofen in trigeminal neuralgia and calcitonin in bone pain), most are broad-spectrum analgesics, useful in neuropathic pain syndromes of multiple etiologies. Within the antiepileptic drug class, gabapentin and carbamazepine can be considered first-line agents, followed by lamotrigine and pregabalin as second-line agents, and the other most recently approved drugs as third-line or ‘salvage’ agents. The tricyclic antidepressants have numerous precautions/contraindications and tolerability issues in this population, thus reducing their utility. Duloxetine and venlafaxine are the only useful analgesics among the modern antidepressants. Challenges for the future include not only the search for more effective and less toxic adjunctive analgesics for the elderly, but also translating our knowledge of current and future analgesics into effective therapies in the ‘real world’ community and institutional settings where elderly people live. There is no justification in our society today for anyone to live with untreated or undertreated persistent pain.

The pharmacotherapy of chronic pain: a review

The past two decades have contributed a large body of preclinical work that has assisted in our understanding of the underlying pathophysiological mechanisms that cause chronic pain. In this context, it has been recognized that effective treatment of pain is a priority and that treatment often involves the use of one or a combination of agents with analgesic action. The current review presents an evidence-based approach to the pharmacotherapy of chronic pain. Medline searches were done for all agents used as conventional treatment in chronic pain. Published papers up to June 2005 were included. The search strategy included randomized, controlled trials, and where available, systematic reviews and meta-analyses. Further references were found in reference sections of papers located using the above search strategy. Agents for which there were no controlled trials supporting efficacy in treatment of chronic pain were not included in the present review, except in cases where preclinical science was compelling, or where initial human work has been positive and where it was thought the reader would be interested in the scientific evidence to date.

Zonisamide at clinically relevant concentrations inhibits field EPSP but not presynaptic fiber volley in rat frontal cortex

We investigated the effect of Zonisamide (ZNS), a newer anti-epileptic drug, on field potentials and neuropropagation in rat frontal cortex, with the aid of the 64-channel multi-electrode dish (MED64) system. The amplitude and propagation of field potentials were expressed dimensionally in the MED64 system. ZNS (3-100 microM) inhibited the amplitude and propagation of field excitatory postsynaptic potentials (fEPSP) in a concentration dependent manner. In contrast, ZNS could not suppress the amplitude and propagation of the presynaptic fiber volley (PrV) at clinically relevant concentrations (10-30 microM). Stimulating dependency with reduction fEPSP was seen in the presence of ZNS at clinically relevant concentrations, but not with PrV. The reduction of fEPSP amplitude was not accompanied by a change in paired-pulse facilitation. These data suggest that at clinically relevant concentrations of ZNS, the suppression of neuronal propagation is at least partially due to the postsynaptic mechanism, probably through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors.

Chronic pain: physiological, diagnostic, and management considerations

Neuropathic pain is a neuropsychiatric condition in which pain is initiated or caused by a primary lesion or dysfunction in the nervous system. Understanding the complexity of neuropathic pain becomes the cornerstone for appropriate diagnosis and management. Diagnosis must take into account comorbid conditions. Successful management depends on realistic patient and physician expectations and an individualized, multidisciplinary approach.