Botanicals and dietary supplements in diabetic peripheral neuropathy

The Influence of Dietary Supplementations on Neuropathic Pain

Neuropathic pain is defined as pain caused by a lesion or disease of the somatosensory nervous system and affects 7–10% of the worldwide population. Neuropathic pain can be induced by the use of drugs, including taxanes, thus triggering chemotherapy-induced neuropathic pain or as consequence of metabolic disorders such as diabetes. Neuropathic pain is most often a chronic condition, and can be associated with anxiety and depression; thus, it negatively impacts quality of life. Several pharmacologic approaches exist; however, they can lead numerous adverse effects. From this perspective, the use of nutraceuticals and diet supplements can be helpful in relieve neuropathic pain and related symptoms. In this review, we discuss how diet can radically affect peripheral neuropathy, and we focus on the potential approaches to ameliorate this condition, such as the use of numerous nutritional supplements or probiotics.

Edible Bird's Nest as a Potential Cognitive Enhancer

Cognitive enhancement is defined as the augmentation of the mind's core capabilities through the improvement of internal or external information processing systems. Recently, the focus has shifted to the potential therapeutic effects of natural products in improving cognitive function. Edible bird's nest (EBN) is a natural food substance derived from the saliva of swiftlets. Until today, EBN is regarded as a high-priced nutritious food with therapeutic effects. The effectiveness of dietary EBN supplementation to enhance brain development in mammals has been documented. Although the neuroprotection of EBN has been previously reported, however, the impact of EBN on learning and memory control and its potential as a cognitive enhancer drug remains unknown. Thus, this article aims to address the neuroprotective benefits of EBN and its potential effect as a cognitive enhancer. Notably, the current challenges and the future study direction in EBN have been demonstrated.

Nutritional Supplements for the Treatment of Neuropathic Pain

Neuropathic pain affects 7-10% of the population and is often ineffectively and incompletely treated. Although the gold standard for treatment of neuropathic pain includes tricyclic antidepressants (TCAs), serotonin-noradrenaline reuptake inhibitors, and anticonvulsants, patients suffering from neuropathic pain are increasingly turning to nonpharmacologic treatments, including nutritional supplements for analgesia. So-called "nutraceuticals" have garnered significant interest among patients seeking to self-treat their neuropathic pain with readily available supplements. The supplements most often used by patients include vitamins such as vitamin B and vitamin D, trace minerals zinc and magnesium, and herbal remedies such as curcumin and St. John's Wort. However, evidence surrounding the efficacy and mechanisms of these supplements in neuropathic pain is limited, and the scientific literature consists primarily of preclinical animal models, case studies, and small randomized controlled trials (RCTs). Further exploration into large randomized controlled trials is needed to fully inform patients and physicians on the utility of these supplements in neuropathic pain. In this review, we explore the basis behind using several nutritional supplements commonly used by patients with neuropathic pain seen in rheumatology clinics.

Peripheral Neuropathy under Oncologic Therapies: A Literature Review on Pathogenetic Mechanisms

Peripheral neurologic complications are frequent adverse events during oncologic treatments and often lead to dose reduction, administration delays with time elongation of the therapeutic plan and, not least, worsening of patients’ quality of life. Experience skills are required to recognize symptoms and clinical evidences and the collaboration between different health professionals, in particular oncologists and hospital pharmacists, grants a correct management of this undesirable occurrence. Some classes of drugs (platinates, vinca alkaloids, taxanes) typically develop this kind of side effect, but the genesis of chemotherapy-induced peripheral neuropathy is not linked to a single mechanism. This paper aims from one side at summarizing and explaining all the scattering mechanisms of chemotherapy-induced peripheral neuropathy through a detailed literature revision, on the other side at finding new approaches to possible treatments, in order to facilitate the collaboration between oncologists, hematologists and hospital pharmacists.

Effectiveness of acupuncture combined mecobalamin in the treatment of elderly diabetic peripheral neuropathy: A protocol of systematic review and meta-analysis

BACKGROUND

Although previous studies have reported the effectiveness of acupuncture combined mecobalamin (AM) in the treatment of elderly diabetic peripheral neuropathy (EDPN), no systematic study has assessed its effectiveness and safety. Thus, this study will evaluate the effectiveness and safety of AM for the treatment of patients with EDPN.

METHODS

Bibliographic electronic databases will be searched as follows: Cochrane Library, PUBMED, EMBASE, CINAHL, PsycINFO, WANGFANG, and China National Knowledge Infrastructure. All of them will be searched from each database initial to March 1, 2020 without language restrictions. All study selection, information extracted, and study quality evaluation will be performed by 2 independent authors. Any disagreements between 2 authors will be resolved by a third author via discussion. RevMan 5.3 software will be used for data pooling and meta-analysis performance if it is possible.

RESULTS

This study will provide synthesis of current evidence of AM for patients with EDPN through primary outcome of glycemic profile, and secondary of neuropathic pain intensity, plantar tactile sensitivity, sensory nerve conduction velocity and motor nerve conduction velocity, health-related quality of life, and adverse events.

CONCLUSION

This study will provide helpful reference for the efficacy and safety of AM for the treatment of patients with EDPN to the clinicians and further studies.Study registration number: INPLASY202040094.

Chinese herbal medicine TangBi Formula treatment of patients with type 2 diabetic distal symmetric polyneuropathy disease: study protocol for a randomized controlled trial

BACKGROUND

Diabetic distal symmetric polyneuropathy (DSPN) is one of the most common microvascular complications of diabetes mellitus, and it has become a major public health problem worldwide because of its high and increasing prevalence, morbidity, and disability rate. The current medications for DSPN are not entirely satisfactory. Preliminary studies indicated that the Chinese herbal TangBi Formula may alleviate signs and symptoms and improve the velocity of nerve conduction in patients with DSPN. This study was designed to determine if Chinese herbal medicine used in combination with conventional treatment is more effective than conventional treatment alone.

METHODS/DESIGN

We are conducting a multicenter, placebo-controlled, double-blind, randomized, controlled clinical trial as a means of assessing the therapeutic effects of traditional Chinese medicine (TCM) treatment. A total of 188 patients will be randomized in a 1:1 ratio to a treatment group (TangBi Formula plus mecobalamin) and a control group (placebo plus mecobalamin). The test period lasts 6 months, during which all of the patients will be given standard medical care as recommended by established guidelines. The primary outcome will be development of differences in changes in clinical symptoms and signs in patients and changes in Michigan Diabetic Neuropathy Score (MDNS) between the two groups before and after treatment. The secondary outcome will be changes in nerve conduction velocity and in single clinical signs and symptoms. Safety assessments and adverse events will also be evaluated.

DISCUSSION

We postulate that patients with DSPN will benefit from therapy that includes TCM. If successful, this work will provide an evidence-based complementary therapeutic approach for treatment of DSPN.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03010241 . Registered on 2 January 2017.

Combination therapy using evening primrose oil and electrical stimulation to improve nerve function following a crush injury of sciatic nerve in male rats

Peripheral nerve injuries with a poor prognosis are common. Evening primrose oil (EPO) has beneficial biological effects and immunomodulatory properties. Since electrical activity plays a major role in neural regeneration, the present study investigated the effects of electrical stimulation (ES), combined with evening primrose oil (EPO), on sciatic nerve function after a crush injury in rats. In anesthetized rats, the sciatic nerve was crushed using small haemostatic forceps followed by ES and/or EPO treatment for 4 weeks. Functional recovery of the sciatic nerve was assessed using the sciatic functional index. Histopathological changes of gastrocnemius muscle atrophy were investigated by light microscopy. Electrophysiological changes were assessed by the nerve conduction velocity of sciatic nerves. Immunohistochemistry was used to determine the remyelination of the sciatic nerve following the interventions. EPO + ES, EPO, and ES obviously improved sciatic nerve function assessed by the sciatic functional index and nerve conduction velocity of the sciatic nerve at 28 days after operation. Expression of the peripheral nerve remyelination marker, protein zero (P0), was increased in the treatment groups at 28 days after operation. Muscle atrophy severity was decreased significantly while the nerve conduction velocity was increased significantly in rats with sciatic nerve injury in the injury + EPO + ES group than in the EPO or ES group. Totally speaking, the combined use of EPO and ES may produce an improving effect on the function of sciatic nerves injured by a crush. The increased expression of P0 may have contributed to improving the functional effects of combination therapy with EPO and ES as well as the electrophysiological and histopathological features of the injured peripheral nerve.

Practical Management of Patients With Painful Diabetic Neuropathy

Purpose

Painful diabetic neuropathy (PDN) has a significant impact on patients’ quality of life, affecting sleep, mood, mobility, ability to work, interpersonal relationships, overall self-worth, and independence. The purpose of this article is to provide diabetes educators with current and essential tools for PDN assessment and management.

Methods

Medline and CINAHL database searches identified publications on the assessment and treatment of PDN. Identified research was evaluated, and information pertinent to diabetes educators was summarized.

Results

Recent advancements in assessment of neuropathic pain include identifying characteristics that distinguish between neuropathic and nonneuropathic pain. In the absence of treatment, research demonstrates that nerve damage may progress while pain diminishes. Many disease-modifying and symptom-management treatment options are available.

Conclusion

Good glycemic control is the first priority for both prevention and management of PDN. However, even with good glycemic control, up to 20% of patients will develop PDN. PDN recognition and assessment are critical to optimize management. Although several treatment modalities are available, few patients obtain complete pain relief. Recent advances in understanding the mechanisms underlying neuropathic pain should lead to better treatment and patient outcomes. Combination therapy, including nonpharmacologic modalities, may be required. Research evaluating the efficacy of combination therapy is needed.

Therapy-related peripheral neuropathy in multiple myeloma patients

This review discusses the most common issues concerning multiple myeloma (MM)-related peripheral neuropathy (PN). This is an important MM complication, observed in up to 54% of newly diagnosed patients, caused by the disease itself or its treatment. Although its aetiology is largely unknown, a number of mechanisms are suspected. It is important to know the neurological status of a patient, as many new antimyeloma medicines can trigger or exacerbate any pre-existing neuropathy. Examples include thalidomide-induced and bortezomib-induced PN (TiPN and BiTN, respectively), which are key MM treatment options. TiPN is usually sensory and sensorimotor, whereas BiPN is typically sensory. The mechanisms of chemotherapy-induced neurotoxicity in MM are well known; thalidomide seems to induce PN through its antiangiogenic properties, whereas bortezomib neurotoxicity is connected with disrupted calcium homeostasis. TiPN incidence ranges from 25% to 75%, and its prevalence and severity appears to be dose-dependent. BiPN incidence is almost 40% and is dose-related as well. Poor (25%) reversibility of TiPN prompted the recommendations for dose and exposure reduction, whereas BiPN cases are mostly reversible (64%). Peripheral sensory neuropathy is very rare in patients receiving bendamustine monotherapy. Because of this favourable toxicity profile, bendamustine may be considered a promising option for combination therapies in pre-existing PN in myeloma patients. Considering the lack of curative therapy for treatment-emergent PN, prevention is a key management strategy in MM patients. All patients should be evaluated for PN before the administration of a neurotoxic drug, and those under treatment should be closely monitored by a neurologist.

Use of natural compounds in the management of diabetic peripheral neuropathy

Nephropathy, retinopathy cardiomyopathy and peripheral neuropathy are all recognized as important complications in about 50% of diabetes mellitus (DM) patients, mostly related to a poor glycemic control or to an improper management of this pathology. In any case, amongst others, diabetic peripheral neuropathy (DPN) seems the leading and most painful complication usually affecting many DM patients. For this reason, this work was conceived to review the large variety of strategies adopted for management of DPN, starting from the most conventional therapies to arrive at alternative approaches. From this perspective, both the most popular pharmacological treatments used to respond to the poorly effect of common analgesics—non-steroidal anti-inflammatory drugs (NSAIDS) and opioids—understood as gabapentin vs. pregabalin clinical use, and the guidelines provided by Oriental Medicine as well as by a long list of natural compounds that many authors identify as possible therapeutic or alternative agents to replace or to combine with the existing therapies will be included. Moreover, in the effort to provide the widest panel of remedies, the most antique techniques of acupuncture and electrostimulation will be considered as alternative, which are useful approaches to take into account in any non-pharmacological strategy for DPN management.

Chinese herbal medicine for diabetic peripheral neuropathy

BACKGROUND

Chinese herbal medicine is frequently used for treating diabetic peripheral neuropathy in China. Many controlled trials have been undertaken to investigate its efficacy.This is an update of a Cochrane review that was first published in the year 2011.

OBJECTIVES

To assess the beneficial effects and harms of Chinese herbal medicine for people with diabetic peripheral neuropathy.

SEARCH METHODS

On 14 May 2012, we searched the Cochrane Neuromuscular Disease Group Specialized Register CENTRAL (2012, Issue 4 in The Cochrane Library), MEDLINE (January 1966 to May 2012), EMBASE (January 1980 to May 2012), AMED (January 1985 to May 2012) and in October 2012, the Chinese Biomedical Database (CBM) (1979 to October 2012), Chinese National Knowledge Infrastructure Database (CNKI) (1979 to October 2012), and VIP Chinese Science and Technique Journals Database (1989 to October 2012). We searched for unpublished literature in the Chinese Conference Papers Database, and Chinese Dissertation Database (from inception to October 2012). There were no language or publication restrictions.

SELECTION CRITERIA

We included randomised controlled trials of Chinese herbal medicine (with a minimum of four weeks treatment duration) for people with diabetic peripheral neuropathy compared with placebo, no intervention, or conventional interventions. Trials of herbal medicine plus a conventional drug versus the drug alone were also included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and evaluated trial quality. We contacted study authors for additional information.

MAIN RESULTS

Forty-nine randomised trials involving 3639 participants were included. All trials were conducted and published in China. Thirty-eight different herbal medicines were tested in these trials, including four single herbs (extracts from a single herb), eight traditional Chinese patent medicines, and 26 self concocted Chinese herbal compound prescriptions. The trials reported on global symptom improvement (including improvement in numbness or pain) and changes in nerve conduction velocity. The positive results described from the 49 studies of low quality are of questionable significance. There was inadequate reporting on adverse events in the included trials. Eighteen trials found no adverse events. Two trials reported adverse events: adverse events occurred in the control group in one trial, and in the other it was unclear in which group the adverse events occurred. 29 trials did not mention whether they monitored adverse events. Conclusions cannot be drawn from this review about the safety of herbal medicines, due to inadequate reporting. Most of the trials were of very low methodological quality and therefore the interpretation of any positive findings for the efficacy of the included Chinese herbal medicines for treating diabetic peripheral neuropathy should be made with caution.

AUTHORS' CONCLUSIONS

Based on this systematic review, there is no evidence to support the objective effectiveness and safety of Chinese herbal medicines for diabetic peripheral neuropathy. No well-designed, randomised, placebo controlled trial with objective outcome measures has been conducted.

Chinese herbal medicine in treatment of diabetic peripheral neuropathy: a systematic review and meta-analysis

AIM OF STUDY

There are multimodal and multidisciplinary approaches to treat diabetic peripheral neuropathy (DPN). However, the intractable adverse effects limited their widespread use. Chinese herbal medicine (CHM) is increasingly used for the treatment of DPN. The aim of this study was to review existing evidence on the effectiveness of CHM for the treatment of DPN.

MATERIALS AND METHODS

Searches were performed with Medline, Embase, Cochrane Central Register of Controlled Trials, CNKI, CBM and Wangfan databases. Controlled trials comparing CHM with other medicine for the treatment of DPN were analyzed.

RESULTS

Eighteen trials met the inclusion criteria. All trials used vitamin B12 and/or B1 as control. Clinical therapeutic effect, divided by three grades including marked effective, effective and ineffective according to the improved degree of subjective symptom, tendon reflex, and nerve conduction velocity, was the only end point reported in all trials, and thus evaluated. The results showed CHM treatment was associated with a superiority in marked effective (odds ratio [OR], 2.40; 95% confidence interval [CI]: 0.94 to 2.97; p<0.001), and effective (OR, 1.39; 95% CI: 1.16 to 1.67; p<0.001). Patients who received CHM treatment was associated with a less likely to report ineffective (OR, 0.26; 95% CI: 0.21 to 0.33, p<0.001). No adverse events were reported in any of the included trials.

CONCLUSIONS

According to the pooled results of our study and the poor quality of the included trials, it might be uncertainty that there was a superiority of CHM for treating DPN. More rigorous controlled trials are required to substantiate or refute these early findings.

Chinese herbal medicine for diabetic peripheral neuropathy

BACKGROUND

Chinese herbal medicine is frequently used for treating diabetic peripheral neuropathy in China. Many controlled trials have been undertaken to investigate its efficacy.

OBJECTIVES

To assess the beneficial effects and harms of Chinese herbal medicine for people with diabetic peripheral neuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Specialized Register (15 June 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 2, 2010 in The Cochrane Library), MEDLINE (January 1966 to June 2010), EMBASE (January 1980 to June 2010), AMED (January 1985 to June 2010), Chinese Biomedical Database (CBM) (1979 to June 2010), Chinese National Knowledge Infrastructure Database (CNKI) (1979 to June 2010), and VIP Chinese Science and Technique Journals Database (1989 to June 2010). We searched for unpublished literature in the Chinese Conference Papers Database and Chinese Dissertation Database (from inception to March 2010). No language or publication restrictions were used.

SELECTION CRITERIA

We included randomized controlled trials of Chinese herbal medicine (with a minimum of four weeks treatment duration) for people with diabetic peripheral neuropathy compared with placebo, no intervention, or conventional interventions. Trials of herbal medicine plus a conventional drug versus the drug alone were also included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and evaluated trial quality. We contacted study authors for additional information. The data analyses were carried out using Review Manager 5.1 (Cochrane software).

MAIN RESULTS

Thirty-nine randomized trials involving 2890 participants were included. All trials were conducted and published in China. Thirty different herbal medicines were tested in these trials, including four single herbs (extracts from a single herb), eight traditional Chinese patent medicines, and 18 self-concocted Chinese herbal compound prescriptions. The trials reported on global symptom improvement (including improvement in numbness or pain) and changes in nerve conduction velocity. There was inadequate reporting on adverse events in the included trials. Most of the trials did not mention whether they monitored adverse effects at all. Only two trials reported adverse events: one occurred in the control group in one trial and in which group was unclear in the other trial . Conclusions cannot be drawn from this review about the safety of herbal medicines due to inadequate reporting. Most of the trials were of low methodological quality and therefore the interpretation of any positive findings for the efficacy of the included Chinese herbal medicines for treating diabetic peripheral neuropathy should be made with caution.

AUTHORS' CONCLUSIONS

Based on this systematic review, there is no evidence to support the objective effectiveness and safety of Chinese herbal medicines for diabetic peripheral neuropathy. No well designed, randomized placebo controlled trial with objective outcome measures has been conducted.

Dealing with neuropathy in plasma-cell dyscrasias

Peripheral neuropathy (PN) is a frequent complication of plasma-cell dyscrasias such as monoclonal gammopathy of undetermined significance, multiple myeloma, Waldenström's disease, POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome, Castleman's disease, and light-chain amyloidosis. PN can be associated with the underlying disease or it can related to the treatment. The novel immunomodulatory drugs thalidomide and lenalidomide and the proteasome inhibitor bortezomib have changed the standard treatment of multiple myeloma. Treatment-related PN induced by thalidomide (TiPN) or bortezomib (BiPN) has become the most frequent cause of symptomatic polyneuropathy in multiple myeloma and related diseases. Dealing with PN has become a major challenge in current clinical practice for multiple myeloma patients. This review deals with practical issues such as etiology, incidence, symptoms, and clinical management of treatment-emergent PN. The major focus of the hematologist should be on the prevention of PN, primarily by frequent monitoring of the patient and by timely and adequate dose reduction of thalidomide and bortezomib. Thalidomide should not be given for periods longer than 18 months, and if it is, then patients should be carefully monitored with a low threshold for discontinuation in the face of any emergent neuropathy. In the case of BiPN, the dose of bortezomib should be reduced and/or the administration interval should be prolonged from biweekly to weekly. Adequate pain management and supportive care require a multidisciplinary approach involving the treating physician, expert nursing staff, and a neurologist as clinically indicated.

Therapy of chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is still a common and disabling side effect of many chemotherapy agents in use today. Unfortunately, neither prophylactic strategies nor symptomatic treatments have proven useful yet. This review will discuss the diagnosis and evaluation of neuropathy in cancer patients, as well as reviewing the various prophylactic and symptomatic treatments that have been proposed or tried. However, sufficient evidence is lacking to recommend any of these treatments to patients suffering with CIPN. Therefore, the best approach is to treat symptomatically, and to start with broad-spectrum analgesic medications such as non-steroidal anti-inflammatory drugs (NSAIDs). If NSAIDs fail, a reasonable second-line agent in properly selected patients may be an opioid. Unfortunately, even when effective in other types of neuropathic pain, anti-depressants and anticonvulsants have not yet proven effective for treating the symptoms of CIPN.

Management of painful diabetic neuropathy

The commonest cause of peripheral neuropathy is diabetes and pain occurs in approximately 30% of diabetic patients with neuropathy. It is extremely distressing for the patient and poses significant difficulties in management, as no treatment to date provides total relief and the side effects of therapy limit dose titration. Understanding the pathogenesis of diabetic neuropathy may lead to the development of new treatments for preventing nerve damage. Furthermore, a better understanding of the mechanisms that modulate pain may lead to more effective relief of painful symptoms. This review provides an update on the assessment and treatment of painful diabetic neuropathy.

Diabetic neuropathy: mechanisms to management

Neuropathy is the most common and debilitating complication of diabetes and results in pain, decreased motility, and amputation. Diabetic neuropathy encompasses a variety of forms whose impact ranges from discomfort to death. Hyperglycemia induces oxidative stress in diabetic neurons and results in activation of multiple biochemical pathways. These activated pathways are a major source of damage and are potential therapeutic targets in diabetic neuropathy. Though therapies are available to alleviate the symptoms of diabetic neuropathy, few options are available to eliminate the root causes. The immense physical, psychological, and economic cost of diabetic neuropathy underscore the need for causally targeted therapies. This review covers the pathology, epidemiology, biochemical pathways, and prevention of diabetic neuropathy, as well as discusses current symptomatic and causal therapies and novel approaches to identify therapeutic targets.

Novel biological properties of Oenothera paradoxa defatted seed extracts: effects on metallopeptidase activity

In this study, for the first time, we used the in vitro metallopeptidase model for the identification of a potential novel activity of defatted evening primrose seed extracts. Prepared extracts of different polarity (aqueous, 60% ethanolic, isopropanolic, and 30% isopropanolic) at concentrations of 1.5-100 microg/mL exhibited a significant and dose dependent inhibition of three tested enzymes. The 50% inhibition of enzymes activity showed that aminopeptidase N (APN) was the enzyme affected to the greatest extent with IC50 at the level of 2.8 microg/mL and 2.9 microg/mL for aqueous and 30% isopropanolic extracts, respectively. The activity of neutral endopeptidase (NEP) was quite strongly inhibited by the extracts as well. The HPLC-DAD analysis and bioguided fractionation led to the identification of four active compounds: (-)-epicatechin gallate, proanthocyanidin B3, oenothein B, and penta-O-galloyl-beta-D-glucose (PGG). Oenothein B has been shown previously to inhibit metallopeptidases. The three other compounds are known to inhibit angiotensin-converting enzyme (ACE), but they have not been previously reported to inhibit the NEP and APN activity. PGG and procyanidins with different degrees of polymerization, as the dominating compounds in O. paradoxa seeds, seemed to play a role in the crude extract activity.

Vitamin B for treating peripheral neuropathy

BACKGROUND

Vitamin B is frequently used for treating peripheral neuropathy but its efficacy is not clear.

OBJECTIVES

The objective of this review was to assess the effects of vitamin B for treating generalised peripheral neuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (searched August 2005), MEDLINE (January 1966 to September 2005), EMBASE (January 1980 to September 2005), Philippine databases (searched September 2005) and reference lists of articles. We also contacted manufacturers and researchers in the field.

SELECTION CRITERIA

Randomised and quasi-randomised trials where vitamin B was compared with placebo or another treatment in generalised peripheral neuropathy.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information.

MAIN RESULTS

Thirteen studies involving 741 participants with alcoholic or diabetic neuropathy were included. In the comparison of vitamin B with placebo, two small trials showed no significant short-term benefit in pain intensity while one of the trials showed a small significant benefit in vibration detection from oral benfotiamine, a derivative of thiamine. In the larger of two trials comparing different doses of vitamin B complex, there was some evidence that higher doses resulted in a significant short-term reduction in pain and improvement in paraesthesiae, in a composite outcome combining pain, temperature and vibration, and in a composite outcome combining pain, numbness and paraesthesiae. There was some evidence that vitamin B is less efficacious than alpha-lipoic acid, cilostazol or cytidine triphosphate in the short-term improvement of clinical and nerve conduction study outcomes but the trials were small. There were few minor adverse effects reported.

AUTHORS' CONCLUSIONS

There are only limited data in randomised trials testing the efficacy of vitamin B for treating peripheral neuropathy and the evidence is insufficient to determine whether vitamin B is beneficial or harmful. One small trial in alcoholic peripheral neuropathy reported slightly greater improvement in vibration perception threshold with oral benfotiamine for eight weeks than placebo. In another small study, a higher dose of oral vitamin B complex for four weeks was more efficacious than a lower dose in reducing symptoms and signs. Vitamin B administered by various routes for two to eight weeks was less efficacious than alpha-lipoic acid, cilostazol or cytidine triphosphate in short-term improvement of clinical and nerve conduction study outcomes. Vitamin B is generally well-tolerated.

Efficacy and safety of alpha-lipoic acid supplementation in the treatment of symptomatic diabetic neuropathy

PURPOSE

The purpose of this article is to review current evidence available for alpha-lipoic acid (ALA) and its ability to improve symptoms of peripheral diabetic neuropathy (PDN).

METHODS

This article searched MEDLINE from 1966 to November 2005 to identify clinical trials that supplemented ALA to individuals with type 1 or type 2 diabetes and positive sensory symptoms of PDN. Clinical trials to be included in this review met specific criteria of randomization, double masking, and placebo-controlled design.

RESULTS

The search results produced 5 clinical trials that met the prerequisites for this review. ALA appears to improve neuropathic symptoms and deficits when administered via parenteral supplementation over a 3-week period. Oral treatment with ALA appears to have more conflicting data whether it improves sensory symptoms or just neuropathic deficits alone. An oral regimen of ALA and optimal length of treatment remains unclear. Both parenteral and up to a 2-year time period of oral supplementation of ALA appears to be safe without affecting glycemic control.

CONCLUSIONS

Based on these results, ALA should be considered as a treatment option for patients with PDN. When discussing supplementation with patients, it is important to discuss potential side effects; vitamin, mineral, and drug interactions; and current evidence available regarding efficacy.

Food-drug interactions via human cytochrome P450 3A (CYP3A)

Food-drug interactions have been reported to occur in various systems in the body. The causes of these interactions are mainly divided into pharmacodynamic and pharmacokinetic processes. Among these processes, drug metabolism plays a crucial role in drug interactions. Metabolic food-drug interactions occur when a certain food alters the activity of a drug-metabolizing enzyme, leading to a modulation of the pharmacokinetics of drugs metabolized by the enzyme. A variety of interactions have been documented so far. Foods consisting of complex chemical mixtures, such as fruits, alcoholic beverages, teas, and herbs, possess the ability to inhibit or induce the activity of drug-metabolizing enzymes. According to results obtained thus far, cytochrome P450 3A4 (CYP3A4) appears to be a key enzyme in food-drug interactions. For example, interactions of grapefruit juice with felodipine and cyclosporine, red wine with cyclosporine, and St John's wort with various medicines including cyclosporine, have been demonstrated. The results indicate the requirement of dosage adjustment to maintain drug concentrations within their therapeutic windows. The CYP3A4-related interaction by food components may be related to the high level of expression of CYP3A4 in the small intestine, as well as its broad substrate specificity, as CYP3A4 is responsible for the metabolism of more than 50% of clinical pharmaceuticals. This review article summarizes the findings obtained to date concerning food-drug interactions and their clinical implications. It seems likely that more information regarding such interactions will accumulate in the future, and awareness is necessary for achieving optimal drug therapy.

Oxidative stress in the pathogenesis of diabetic neuropathy

Oxidative stress results from a cell or tissue failing to detoxify the free radicals that are produced during metabolic activity. Diabetes is characterized by chronic hyperglycemia that produces dysregulation of cellular metabolism. This review explores the concept that diabetes overloads glucose metabolic pathways, resulting in excess free radical production and oxidative stress. Evidence is presented to support the idea that both chronic and acute hyperglycemia cause oxidative stress in the peripheral nervous system that can promote the development of diabetic neuropathy. Proteins that are damaged by oxidative stress have decreased biological activity leading to loss of energy metabolism, cell signaling, transport, and, ultimately, to cell death. Examination of the data from animal and cell culture models of diabetes, as well as clinical trials of antioxidants, strongly implicates hyperglycemia-induced oxidative stress in diabetic neuropathy. We conclude that striving for superior antioxidative therapies remains essential for the prevention of neuropathy in diabetic patients.

Herbal remedies in the United States: potential adverse interactions with anticancer agents

PURPOSE

Interest in the use of herbal products has grown dramatically in the Western world. Recent estimates suggest an overall prevalence for herbal preparation use of 13% to 63% among cancer patients. With the narrow therapeutic range associated with most anticancer drugs, there is an increasing need for understanding possible adverse drug interactions in medical oncology.

METHODS

In this article, a literature overview is provided of known or suspected interactions of the 15 best-selling herbs in the United States with conventional allopathic therapies for cancer.

RESULTS

Herbs with the potential to significantly modulate the activity of drug-metabolizing enzymes (notably cytochrome p450 isozymes) and/or the drug transporter P-glycoprotein include garlic (Allium sativum), ginkgo (Ginkgo biloba), echinacea (Echinacea purpurea), ginseng (Panax ginseng), St John' s wort (Hypericum perforatum), and kava (Piper methysticum). All of these products participate in potential pharmacokinetic interactions with anticancer drugs.

CONCLUSION

It is suggested that health care professionals and consumers should be aware of the potential for adverse interactions with these herbs, question their patients on their use of them, especially among patients whose disease is not responding to treatments as expected, and urge patients to avoid herbs that could confound their cancer care.

The use of complementary and alternative medicines by patients with peripheral neuropathy

Complementary and alternative medicine (CAM) therapies have become increasingly popular and are used regularly by patients with chronic neurological disorders. The prevalence and characteristics of CAM use by patients with peripheral neuropathy is unknown. We performed a prospective, questionnaire-based study to determine the prevalence and patterns of use of CAM therapies in 180 consecutive outpatients with peripheral neuropathy. The use of CAM was reported by 77 patients (43%) with neuropathy. The most frequent were megavitamins (35%), magnets (30%), acupuncture (30%), herbal remedies (22%), and chiropractic manipulation (21%); 37 (48%) tried more than one form of alternative treatment. Seventeen respondents (27%) thought their neuropathy symptoms improved with these approaches. Those who used CAM were slightly younger (mean age 62 vs. 65 years, p = 0.05) and more often college educated (39% vs. 24%, p = 0.03) compared to CAM nonusers. They also more often reported burning neuropathic pain (62% vs. 44%, p = 0.01). Patients with diabetic neuropathy used CAM more frequently than others (p = 0.03). The most common reason for using CAM was inadequate pain control (32%). Almost half of patients did not consult a physician before starting CAM. We conclude that there is a high prevalence of CAM use in our patients with neuropathy, and one-quarter reported that their symptoms improved. CAM users were better educated than nonusers, but most did not discuss CAM treatments with their physician. Neuropathic pain was substantially more common in CAM users, and lack of pain control was the most common reason for CAM use.

Nutritional Approaches to Late Toxicities of Adjuvant Chemotherapy in Breast Cancer Survivors

Adjuvant chemotherapy of breast cancer reduces recurrence rates and prolongs survival at the cost of both acute and chronic toxicities. Breast cancer survivors who have received adjuvant chemotherapy may suffer from late effects of chemotherapy including congestive heart failure, neuropathy, premature menopause, and osteoporosis. Nutritional approaches to these problems are distinct in their orientation and success. Study of free radical scavengers for anthracycline-induced cardiomyopathy was born from known pathogenetic mechanisms of cardiotoxicity but has been universally disappointing thus far in clinical trials. Application of agents used for diabetic neuropathy suggests that evening primrose oil, alpha-lipoic acid, and capsaicin may all play a role in the empiric options available to patients with chemotherapy-induced neuropathy. Plant-derived preparations including black cohosh (Actaea racemosa), dong quai (Angelica sinensis), evening primrose (Oenothera biennis), and red clover (Trifolium pretense) are used by patients experiencing hot flashes due to premature menopause despite a paucity of clinical trial data demonstrating either safety or efficacy. Calcium and vitamin D are widely accepted as an effective means to retard bone loss leading to osteoporosis. Nutritional approaches to late effects of breast cancer chemotherapy offer the prospect of preventing or ameliorating these sequelae of treatment. However, except for vitamin D and calcium for prevention of bone loss, current clinical evidence supporting use of nutritional agents remains sparse.