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ORIGINAL ARTICLE
Year : 2006  |  Volume : 54  |  Issue : 2  |  Page : 173--177

Effectiveness of oxcarbazepine in symptomatic treatment of painful diabetic neuropathy

A Kemal Erdemoglu, Ayhan Varlibas 
 Department of Neurology, Faculty of Medicine, University of Kirikkale, Kirikkale, Turkey

Correspondence Address:
A Kemal Erdemoglu
Cinnah Cad. Kirkpinar sok. 12/4, Cankaya, Ankara, 06690
Turkey

Abstract

Background: Both basic and clinical research has demonstrated that antiepileptic drugs can be effective in alleviating neuropathic pain. It was hypothesized that oxcarbazepine might be effective in reducing the symptoms of painful diabetic neuropathy. Aims: To investigate the long-term efficacy and safety of oxcarbazepine in symptoms of painful diabetic neuropathy. Materials and Methods: This study included thirty-eight painful diabetic neuropathy patients, which were screened with clinical assessment and electrophysiological studies. The efficacy and safety of oxcarbazepine were evaluated according to the changes in pain intensity and social interference subitems scores of Short-form Brief Pain Inventory besides electrophysiological studies at the end of six months of the treatment. Statistical Analysis: The Students t, Mann-Whitney U and Rank Sum test and Chi-square tests were applied to examine variables differences. The level of statistical significance was chosen to be P <0.05. Results: A significant difference was found in all of subitems of pain intensity and social interference at the end of the study according to the baseline scores. Improvement was observed in 52.7%, 63.1%, 55.3% and 63.2% of patients for worst, least, average and pain right now at the end of six months, respectively. Improvement was observed as 60.6%, 63.2%, 52.6%, 60.5%, 68.4% and 63.2% for general activity, mood, walk, work, people relations, sleep and life enjoyment subitems, respectively. None of these patients had any prominent side effect leading to discontinue the treatment. Conclusion: Long-term oxcarbazepine treatment was found to be effective and safe in the symptoms of painful diabetic neuropathy.



How to cite this article:
Erdemoglu A K, Varlibas A. Effectiveness of oxcarbazepine in symptomatic treatment of painful diabetic neuropathy.Neurol India 2006;54:173-177


How to cite this URL:
Erdemoglu A K, Varlibas A. Effectiveness of oxcarbazepine in symptomatic treatment of painful diabetic neuropathy. Neurol India [serial online] 2006 [cited 2021 Jun 20 ];54:173-177
Available from: https://www.neurologyindia.com/text.asp?2006/54/2/173/25966


Full Text

 Introduction



The complex pathophysiology and difficult-to-treat nature of diabetic neuropathy symptoms remains an important clinical challenge. A large number of drugs with different mechanisms of action on pain symptom of diabetic neuropathy have been tried such as certain anticonvulsants, antidepressant drugs or local anesthetics. [1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12] Because of the limitations of the available treatment modalities, new agents that are effective and safe need to be search for patients with diabetic neuropathy. Oxcarbazepine is one of the new derivatives of anti-epileptic agents. Although its pharmaco-dynamical effects are similar to carbamazepine, the profile of oxcarbazepine has lack of side effects common to carbamazepine. Thus, we aimed to investigate long-term efficacy and safety of oxcarbazepine in painful diabetic neuropathy.

 Materials and Methods



The study was conducted in Department of Neurology, Faculty of Medicine, between December 2003 and December 2004. The Ethics Committee of Medical School approved the study. All patients were required to sign an informed consent before participation in the study.

Patients with type II diabetes mellitus were eligible for the study. All patients were receiving oral anti-diabetic medication during under the care of an endocrinologist. Diabetes mellitus was diagnosed as recommended by American Diabetes Association.[13] Patients with glycosylated hemoglobin less than 6.7% at the initial evaluation and patients with causes of neuropathy other than diabetes mellitus were ineligible.

A detailed medical history was obtained and an electrocardiogram was performed at the screening visit. Clinical laboratory tests (hematology, blood chemistries including electrolytes, glucose, lipid profile, liver, renal and thyroid function tests, total glycosylated hemoglobin and urinalysis) were performed at the beginning of the study and the final visit at the sixth month. Plasma glucose and HbA1C levels also were measured before and at the end of the treatment phase. There was no significant change in HbA[1]c over the treatment period.

Patients were enrolled into the study if they are eligible for the followings:

1. Ages between 18 to 65 years

2. Distal symmetrical polyneuropathy was indicated by medical history, neurological examination and abnormal nerve conduction test results (Michigan Neuropathy Screening Instrument)

3. Pain attributed to diabetic neuropathy had been present for at least 6 months

4. A mean pain intensity of at least four on an 10-point numerical pain scale (VAS 0 to 10 0 means no pain, 10 means the worst imaginable pain) and

5. Patients with serum sodium levels between 134 and 146 m Eq/L at baseline were enrolled.

Patients were excluded from participation for any of the following reasons:

1. Known contraindication to or prior use of any anticonvulsant

2. Peripheral neuropathy attributable to other causes such as alcoholism, connective tissue disease, or toxic exposure

3. Severe depression

4. Estimated creatinin clearance P P P Increasing evidence suggests that oxcarbazepine can provide significant analgesia in several neuropathic pain conditions, including trigeminal neuralgia and PDN and is also may be effective in treating neuropathic pain refractory to other AEDs, such as carbamazepine and gabapentin. Thus, we aimed to investigate long-term efficacy and safety of oxcarbazepine in painful diabetic neuropathy.

Oxcarbazepine, an anti-epileptic, a keto-analog of carbamazepine, was shown to be effective in reducing pain in animal model.[23],[24],[25],[26] It has been reported that oxcarbazepine acts on inhibiting sustained, high frequency voltage-gated sodium channels merged with the high voltage P/Q and N-type calcium channels.[23],[24],[25],[26],[27] The effectiveness of oxcarbazepine in treating neuropathic pain is probably due to its dual mode of action, which differentiates oxcarbazepine from other AEDs.

In our study, we had used BPI-sf comprising pain intensity and social interference (general activity, mood, walk, work, people relations, sleep and life enjoyment) subitems. A significant change in pain intensity and social interference subitems of BPI-sf was observed in diabetic neuropathic patients at the end of 6 months of the treatment ( P et al reported that oxcarbazepine was effective in reducing the mean visual analog scale score about 48% in thirty diabetic neuropathy patients. In Beydoun's study, although seven of the eight health concepts of Medical Outcomes Study Short Form 36 had been improved, only the bodily pain was reported to be improved statistically.[17] Recently, Dogra et al demonstrated in a randomized, multicenter, double-blind, placebo-controlled trial that OXC was effective in the treatment of painful diabetic neuropathy. It was reported that the results of the study showed that OXC significantly reduced pain severity from VAS scores ( P =.01), more rapid onset of pain relief ( P =.02, 22.5 versus 30.7 d), improvement ( P =.0025, 48% versus 22%) and lower proportion of nights with awakening because of pain versus placebo (31% vs 49%, P =.02).[28] The results of our study were similar with these two studies showing that oxcarbazepine had improved the quality of life significantly in patients with painful diabetic neuropathy. The effect on the life style of sufferers can be devastating, with loss of functions, social and workdays, quality of life should be inquired besides pain in order to evaluate the effectiveness of the treatment.

The recommended anticonvulsant dose of oxcarbazepine is 900-1200 mg/day. Therefore, in this study, oxcarbazepine with a dosage of 150 mg/day was initiated and titrated every other day up to 1200 mg. The dosage of and titration of oxcarbazepine was similar with the other study and the side effects were transient and mild. The most frequent side effect was dizziness and nausea. However, both our and Beydoun et al .'s studies had a limited number of patients a significant effect may also be achieved in a larger group of patients. The other side effects of oxcarbazepine are sedation, headache, dizziness, rash, vertigo, ataxia, nausea, diplopia and hyponatremia. The frequency of hyponatremia with oxcarbazepine has been reported to range from 22 to 73%. There is no significant serum Na level change at the end of our study.

Limitations of the study included, no control group was taken and could not study placebo effect on parameters. In Beydoun et al .'s study, it was shown that the effect of oxcarbazepine was almost stable after fifth week, at the end of titration phase.[17] In our study, we did not evaluate the start of effectiveness or the change in week, since our main aim was to evaluate the effectiveness in the long-term use of oxcarbazepine.

To our knowledge, there is not any study for evaluating the long-term effectiveness of oxcarbazepine in diabetic neuropathic patients. In this study, oxcarbazepine was found to be effective and safe in long-term symptomatic treatment of painful diabetic neuropathy.

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