Acetyl-L-carnitine in HIV-associated antiretroviral toxic neuropathy

Carnitine Responsive Migraine Headache Syndrome: Case Report and Review of the Literature

PURPOSE OF REVIEW

To review carnitine's role in migraine and headache, present a case of a patient with intractable chronic migraine refractory to medications but exquisitely responsive to mitochondrial cofactors with a particularly prompt response to L-carnitine supplementation with dose response, and suggest scenarios where L-carnitine could be considered for prophylactic treatment in migraine and intractable headache with migraine features.

RECENT FINDINGS

Multiple treatments modalities are used to treat migraine, including nutraceutical therapies. Mitochondrial supplements are often used to treat migraine, based on controlled trials. One of the nutraceutical therapies used in neurological and non-neurological conditions is L-carnitine. A few studies have examined the effect of carnitine in patients with migraine. We present a case of a patient with chronic migraine-like headaches found to have carnitine deficiency whose headaches greatly improved with carnitine supplementation. This case suggests that secondary carnitine deficiency may cause chronic migraine. Energy deficiency states occur with migraine, and replenishment of energy substrates has demonstrated some improvement in migraine. Recent studies suggest that L-carnitine with other mitochondrial cofactors may be migraine preventives. The exact link between carnitine and migraine is unknown. Perhaps carnitine deficiency should be in the differential for refractory migraine. Supplementation with L-carnitine merits exploration as a nutraceutical treatment of chronic migraine. Our case suggests that there may be a dose-dependent response to L-carnitine.

HIV in the cART era and the mitochondrial: immune interface in the CNS

HIV-associated neurocognitive disorders (HAND) persist in the era of effective combined antiretroviral therapy (cART). A large body of literature suggests that mitochondrial dysfunction is a prospective etiology of HAND in the cART era. While viral load is often suppressed and the immune system remains intact in HIV+ patients on cART, evidence suggests that the central nervous system (CNS) acts as a reservoir for virus and low-level expression of viral proteins, which interact with mitochondria. In particular, the HIV proteins glycoprotein 120, transactivator of transcription, viral protein R, and negative factor have each been linked to mitochondrial dysfunction in the brain. Moreover, cART drugs have also been shown to have detrimental effects on mitochondrial function. Here, we review the evidence generated from human studies, animal models, and in vitro models that support a role for HIV proteins and/or cART drugs in altered production of adenosine triphosphate, mitochondrial dynamics, mitophagy, calcium signaling and apoptosis, oxidative stress, mitochondrial biogenesis, and immunometabolism in the CNS. When insightful, evidence of HIV or cART-induced mitochondrial dysfunction in the peripheral nervous system or other cell types is discussed. Lastly, therapeutic approaches to targeting mitochondrial dysfunction have been summarized with the aim of guiding new investigations and providing hope that mitochondrial-based drugs may provide relief for those suffering with HAND.

Nucleoside reverse transcriptase inhibitors induced hepatocellular mitochondrial DNA lesions and compensatory enhancement of mitochondrial function and DNA repair

Nucleoside reverse transcriptase inhibitors (NRTIs) are the backbone of combined antiretroviral therapy (cART) and are widely used in anti-human immunodeficiency virus (HIV) therapy. Long-term administration of NRTIs can result in mitochondrial dysfunction in certain HIV-1-infected patients. However, NRTI-associated liver mitochondrial toxicity is not well known. Herein, the liver autopsy of acquired immune deficiency syndrome (AIDS) patients and the liver tissues of mice with 12 months of NRTI exposure were used to identify NRTI-associated liver toxicity with immunofluorescence, quantitative real-time polymerase chain reaction (qPCR), Amplex red and horseradish peroxidase, and cloning and sequencing. Laser capture microdissection was used to capture hepatocytes from liver tissues. We observed DNA oxidative damage and mitochondrial DNA (mtDNA) loss in the livers of AIDS patients, and cART patients had higher DNA oxidative damage and lower DNA repair function in liver tissues than non-cART patients. We also observed liver oxidative damage, increased DNA repair and mtDNA loss in mice with exposure to four different NRTIs for 12 months, and hepatocytes had no more mtDNA loss than liver tissues. Although NRTIs could induce mitochondrial hydrogen peroxide production, increased mitochondrial oxygen consumption was found with a Clark-type electrode. The captured hepatocytes had greater diversity in their mtDNA D-loop, dehydrogenase subunit1 (ND1) and ND4 than the controls. Long-term NRTI exposure induced single nucleotide variation in hepatocellular mtDNA D-loop, ND1 and ND4. Our findings indicate that NRTIs can induce liver mtDNA lesions, but simultaneously enhance mitochondrial function and mtDNA repair.

Natural products and complementary therapies for chemotherapy-induced peripheral neuropathy: A systematic review

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious dose-limiting side-effect without any FDA-approved treatment option. Prior reviews focus mostly on pharmacological interventions, but nonpharmaceutical interventions have also been evaluated. A Web of Science and PubMed database search to identify relevant RCTs from January 2005 to May 2015 included the terms: CIPN, cancer; and supplements, vitamin E, goshajinkigan, kampo, acetyl-L-carnitine, carnitine, alpha-lipoic acid, omega-3, glutamine, or glutamate; or massage, acupuncture, mind-body practice, yoga, meditation, Tai-Chi, physical activity, or exercise. Of 1465 publications screened, 12 RCTs evaluated natural products and one evaluated electroacupuncture. Vitamin E may help prevent CIPN. L-Glutamine, goshajinkigan, and omega-3 are also promising. Acetyl-L-carnitine may worsen CIPN and alpha-lipoic acid activity is unknown. Electroacupuncture was not superior to placebo. No RCTs were published regarding other complementary therapies, although some studies mention positive incidental findings. Natural products and complementary therapies deserve further investigation, given the lack of effective CIPN interventions.

Mitochondrial DNA D-loop AG/TC transition mutation in cortical neurons of mice after long-term exposure to nucleoside analogues

With the wide application of combined antiretroviral therapy, the prognosis of human immunodeficiency virus (HIV)-1 infected patient has been significantly improved. However, long-term administration of antiretroviral drugs can result in various drug-associated toxicities. Among them, nucleoside analogues were confirmed to inhibit DNA polymerase gamma, resulting in mitochondrial toxicity. Our previous study indicated that long-term exposure of mice to nucleoside analogue could induce mitochondria DNA (mtDNA) loss in cortical neurons. Herein, we further identify mitochondrial toxicity of four nucleoside analogues (zidovudine (AZT), stavudine (D4T), lamivudine (3TC), and didanosine (DDI)) by cloning and sequencing mtDNA D-loop region in mice neurons captured with laser capture microdissection. The results showed that mutation of neuronal mtDNA D-loop sequences increased in mice treated with each of the four nucleoside analogues for 4 months and D4T and DDI induced more severe D-loop lesion than the other two nucleoside analogues. The major type of D-loop point mutations induced by four nucleoside analogues was transition, in particular of "A→G" and "T→C" transition, but the point transition sites were variable. Our findings suggest that long-term exposure to nucleoside analogue can result in mtDNA D-loop region lesion in mouse cortical neurons.

In vitro assessment of antiretroviral drugs demonstrates potential for ototoxicity

Several studies have reported an increased incidence of auditory dysfunction among HIV/AIDS patients. We used auditory HEI-OC1 cells in cell viability, flow cytometry and caspases 3/7-activation studies to investigate the potential ototoxicity of fourteen HIV antiretroviral agents: Abacavir, AZT, Delavirdine, Didenosine, Efavirenz, Emtricitabine, Indinavir, Lamivudine, Nefinavir, Nevirapine, Tenofovir, Ritonavir, Stavudine and Zalcitabine, as well as combinations of these agents as used in the common anti-HIV cocktails Atripla™, Combivir™, Epzicom™, Trizivir™, and Truvada™. Our results suggested that most of the single assayed anti-HIV drugs are toxic for HEI-OC1 auditory cells. The cocktails, on the other hand, decreased auditory cells' viability with high significance, with the following severity gradient: Epzicom ∼ Trizivir >> Atripla ∼ Combivir > Truvada. Interestingly, our results suggest that Trizivir- and Epzicom-induced cell death would be mediated by a caspase-independent mechanism. l-Carnitine, a natural micronutrient known to protect HEI-OC1 cells against some ototoxic drugs as well as to decrease neuropathies associated with anti-HIV treatments, increased viability of cells treated with Lamivudine and Tenofovir as well as with the cocktail Atripla, but had only minor effects on cells treated with other drugs and drug combinations. Altogether, these results suggest that some frequently used anti-HIV agents could have deleterious effects on patients' hearing, and provide arguments in favor of additional studies aimed at elucidating the potential ototoxicity of current as well as future anti-HIV drugs.

Long-term exposure of mice to nucleoside analogues disrupts mitochondrial DNA maintenance in cortical neurons

Nucleoside analogue reverse transcriptase inhibitor (NRTI), an integral component of highly active antiretroviral therapy (HAART), was widely used to inhibit HIV replication. Long-term exposure to NRTIs can result in mitochondrial toxicity which manifests as lipoatrophy, lactic acidosis, cardiomyopathy and myopathy, as well as polyneuropathy. But the cerebral neurotoxicity of NRTIs is still not well known partly due to the restriction of blood-brain barrier (BBB) and the complex microenvironment of the central nervous system (CNS). In this study, the Balb/c mice were administered 50 mg/kg stavudine (D4T), 100 mg/kg zidovudine (AZT), 50 mg/kg lamivudine (3TC) or 50 mg/kg didanosine (DDI) per day by intraperitoneal injection, five days per week for one or four months, and primary cortical neurons were cultured and exposed to 25 µM D4T, 50 µM AZT, 25 µM 3TC or 25 µM DDI for seven days. Then, single neuron was captured from mouse cerebral cortical tissues by laser capture microdissection. Mitochondrial DNA (mtDNA) levels of the primary cultured cortical neurons, and captured neurons or glial cells, and the tissues of brains and livers and muscles were analyzed by relative quantitative real-time PCR. The data showed that mtDNA did not lose in both NRTIs exposed cultured neurons and one month NRTIs treated mouse brains. In four months NRTIs treated mice, brain mtDNA levels remained unchanged even if the mtDNA levels of liver (except for 3TC) and muscle significantly decreased. However, mtDNA deletion was significantly higher in the captured neurons from mtDNA unchanged brains. These results suggest that long-term exposure to NRTIs can result in mtDNA deletion in mouse cortical neurons.

Impact on L-carnitine Homeostasis of Short-term Treatment with the Pivalate Prodrug Tenofovir Dipivoxil

Pivalate-generating prodrugs have been suggested to cause clinically significant hypocarnitinaemia. Tenofovir dipivoxil, a novel ester prodrug of tenofovir, can be used for treatment for hepatitis B and HIV infection and it was necessary to evaluate the effect of its treatment on carnitine homeostasis. We sought to investigate the effect of Class 1 drug tenofovir dipivoxil on endogenous L-carnitine level during a 72-hr test in healthy Chinese volunteers and to establish a suitable dose of L-carnitine nutritional supplement for patients who were administered short-term tenofovir dipivoxil tablets for treatment for hepatitis B and herpes simplex virus infection. Tenofovir dipivoxil was administered in one of eight dosing regimens (single dose 150, 300 and 600 mg, multiple dose 300, 450, and 600 mg, multiple dose 450 (600) mg tenofovir dipivoxil and 0.5 g L-carnitine) to gender-balanced groups of 84 healthy Chinese volunteers. Plasma concentrations of L-carnitine were quantified before, during and after treatment. Plasma L-carnitine concentrations fell during tenofovir dipivoxil dosing. The nadir in L-carnitine concentration was dependent on the dose of tenofovir dipivoxil and it decreased from 6.1 ± 0.6 to 4.4 ± 0.8 μg/ml, 6.1 ± 1.8 to 3.3 ± 1.2 μg/ml, 6.2 ± 0.6 to 2.5 ± 0.5 μg/ml for single doses of 150, 300, 600 mg tenofovir dipivoxil tablets and from 6.0 ± 1.4 to 2.1 ± 1.5 μg/ml, 6.2 ± 0.4 to 0.9 ± 0.5 μg/ml for multiple doses of 450, 600 mg tenofovir dipivoxil tablets, respectively. Short-term administration of tenofovir dipivoxil results in hypocarnitinaemia and increased losses of carnitine in resulting of minor adverse events of decreased food appetite, nausea, abdominal distention and muscle weakness.

Diagnosis and management of pediatric peripheral neuropathies in resource-poor settings

The diagnosis of a peripheral neuropathy in a child who resides in the majority of resource-poor settings is based on the history taken and the clinical examination. The majority of children, unless they demonstrate additional clinical markers, will lack a more definitive diagnosis beyond the label ‘peripheral neuropathy’. The treatable, typically acquired conditions, which are prevalent in these settings, are the priority to identify. This would include neuroinfections, neuroinflammation, toxins and vitamin deficiencies. The management of children with peripheral neuropathies in resource-poor settings must be approached in a different manner to that of more ‘resource-equipped’ settings. Secondary or tertiary centers are scarce, often significant distances away from the patient, and this leads to long delays before access is possible. Most children present to primary healthcare settings and are seen by practitioners with little training in the features suggestive of a peripheral neuropathy. As such, basic aids to assist the healthcare worker in the early recognition and interventions of a child with a peripheral neuropathy are important. In addition, there must be recognition of the child with a rapidly progressive neuropathy where a life-threatening condition is present, and urgent referral to a tertiary setting made wherever possible.

L-acetylcarnitine causes rapid antidepressant effects through the epigenetic induction of mGlu2 receptors

Epigenetic mechanisms are involved in the pathophysiology of depressive disorders and are unique potential targets for therapeutic intervention. The acetylating agent L-acetylcarnitine (LAC), a well-tolerated drug, behaves as an antidepressant by the epigenetic regulation of type 2 metabotropic glutamate (mGlu2) receptors. It caused a rapid and long-lasting antidepressant effect in Flinders Sensitive Line rats and in mice exposed to chronic unpredictable stress, which, respectively, model genetic and environmentally induced depression. In both models, LAC increased levels of acetylated H3K27 bound to the Grm2 promoter and also increased acetylation of NF-ĸB-p65 subunit, thereby enhancing the transcription of Grm2 gene encoding for the mGlu2 receptor in hippocampus and prefrontal cortex. Importantly, LAC reduced the immobility time in the forced swim test and increased sucrose preference as early as 3 d of treatment, whereas 14 d of treatment were needed for the antidepressant effect of chlorimipramine. Moreover, there was no tolerance to the action of LAC, and the antidepressant effect was still seen 2 wk after drug withdrawal. Conversely, NF-ĸB inhibition prevented the increase in mGlu2 expression induced by LAC, whereas the use of a histone deacetylase inhibitor supported the epigenetic control of mGlu2 expression. Finally, LAC had no effect on mGlu2 knockout mice exposed to chronic unpredictable stress, and a single injection of the mGlu2/3 receptor antagonist LY341495 partially blocked LAC action. The rapid and long-lasting antidepressant action of LAC strongly suggests a unique approach to examine the epigenetic hypothesis of depressive disorders in humans, paving the way for more efficient antidepressants with faster onset of action.

N-Acetyl-cysteine causes analgesia by reinforcing the endogenous activation of type-2 metabotropic glutamate receptors

Background

Pharmacological activation of type-2 metabotropic glutamate receptors (mGlu2 receptors) causes analgesia in experimental models of inflammatory and neuropathic pain. Presynaptic mGlu2 receptors are activated by the glutamate released from astrocytes by means of the cystine/glutamate antiporter (System x_c^- or Sx_c^-). We examined the analgesic activity of the Sx_c^- activator, N-acetyl-cysteine (NAC), in mice developing inflammatory or neuropathic pain.

Results

A single injection of NAC (100 mg/kg, i.p.) reduced nocifensive behavior in the second phase of the formalin test. NAC-induced analgesia was abrogated by the Sx_c^- inhibitor, sulphasalazine (8 mg/kg, i.p.) or by the mGlu2/3 receptor antagonist, LY341495 (1 mg/kg, i.p.). NAC still caused analgesia in mGlu3^−/− mice, but was inactive in mGlu2^−/− mice. In wild-type mice, NAC retained the analgesic activity in the formalin test when injected daily for 7 days, indicating the lack of tolerance. Both single and repeated injections of NAC also caused analgesia in the complete Freund’s adjuvant (CFA) model of chronic inflammatory pain, and, again, analgesia was abolished by LY341495. Data obtained in mice developing neuropathic pain in response to chronic constriction injury (CCI) of the sciatic nerve were divergent. In this model, a single injection of NAC caused analgesia that was reversed by LY341495, whereas repeated injections of NAC were ineffective. Thus, tolerance to NAC-induced analgesia developed in the CCI model, but not in models of inflammatory pain. The CFA and CCI models differed with respect to the expression levels of xCT (the catalytic subunit of Sx_c^-) and activator of G-protein signaling type-3 (AGS3) in the dorsal portion of the lumbar spinal cord. CFA-treated mice showed no change in either protein, whereas CCI mice showed an ipislateral reduction in xCT levels and a bilateral increase in AGS3 levels in the spinal cord.

Conclusions

These data demonstrate that pharmacological activation of Sx_c^- causes analgesia by reinforcing the endogenous activation of mGlu2 receptors. NAC has an excellent profile of safety and tolerability when clinically used as a mucolytic agent or in the management of acetaminophen overdose. Thus, our data encourage the use of NAC for the experimental treatment of inflammatory pain in humans.

Antiretroviral therapy in Indian setting: when & what to start with, when & what to switch to?

With the rapid scale up of antiretroviral therapy, there is a dramatic decline in HIV related morbidity and mortality in both developed and developing countries. Several new safe antiretroviral, and newer class of drugs and monitoring assays are developed recently. As a result the treatment guideline for the management of HIV disease continue to change. This review focuses on evolving science on Indian policy - antiretroviral therapy initiation, which drugs to start with, when to change the initial regimen and what to change.

Metabolic correction in the management of diabetic peripheral neuropathy: improving clinical results beyond symptom control

Current Clinical Management Guidelines of Diabetic Peripheral Neuropathy (DPN) are based on adequate glucose control and symptomatic pain relief. However, meticulous glycemic control could delay the onset or slow the progression of diabetic neuropathy in patients with DM type 2, but it does not completely prevent the progression of the disease. Complications of DPN as it continues its natural course, produce increasing pain and discomfort, loss of sensation, ulcers, infections, amputations and even death. In addition to the increased suffering, disability and loss of productivity, there is a very significant economic impact related to the treatment of DPN and its complications. In USA alone, it has been estimated that there are more than 5,000,000 patients suffering from DPN and the total annual cost of treating the disease and its complications is over $10,000 million dollars. In order to be able to reduce complications of DPN, it is crucial to improve or correct the metabolic conditions that lead to the pathology present in this condition. Pathophysiologic mechanisms implicated in diabetic neuropathy include: increased polyol pathway with accumulation of sorbitol and reduced Na+/K+-ATPase activity, microvascular damage and hypoxia due to nitric oxide deficit and increased oxygen free radical activity. Moreover, there is a decrease in glutathione and increase in homocysteine. Clinical trials in the last two decades have demonstrated that the use of specific nutrients can correct some of these metabolic derangements, improving symptom control and providing further benefits such as improved sensorium, blood flow and nerve regeneration. We will discuss the evidence on lipoic acid, acetyl-L-carnitine, benfotiamine and the combination of active B vitamins L-methylfolate, methylcobalamin and piridoxal-6-phosphate. In addition, we discuss the role of metformin, an important drug in the management of diabetes, and the presence of specific polymorphic genes, in the risk of developing DPN and how metabolic correction can reduce these risks.

Pharmacological treatment of painful HIV-associated sensory neuropathy: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Significant pain from HIV-associated sensory neuropathy (HIV-SN) affects ∼40% of HIV infected individuals treated with antiretroviral therapy (ART). The prevalence of HIV-SN has increased despite the more widespread use of ART. With the global HIV prevalence estimated at 33 million, and with infected individuals gaining increased access to ART, painful HIV-SN represents a large and expanding world health problem. There is an urgent need to develop effective pain management strategies for this condition.

METHOD AND FINDINGS

OBJECTIVE

To evaluate the clinical effectiveness of analgesics in treating painful HIV-SN.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, Cochrane central register of controlled trials, www.clinicaltrials.gov, www.controlled-trials.com and the reference lists of retrieved articles.

SELECTION CRITERIA

Prospective, double-blinded, randomised controlled trials (RCTs) investigating the pharmacological treatment of painful HIV-SN with sufficient quality assessed using a modified Jadad scoring method.

REVIEW METHODS

Four authors assessed the eligibility of articles for inclusion. Agreement of inclusion was reached by consensus and arbitration. Two authors conducted data extraction and analysis. Dichotomous outcome measures (≥ 30% and ≥ 50% pain reduction) were sought from RCTs reporting interventions with statistically significant efficacies greater than placebo. These data were used to calculate RR and NNT values.

RESULTS

Of 44 studies identified, 19 were RCTs. Of these, 14 fulfilled the inclusion criteria. Interventions demonstrating greater efficacy than placebo were smoked cannabis NNT 3.38 95%CI(1.38 to 4.10), topical capsaicin 8%, and recombinant human nerve growth factor (rhNGF). No superiority over placebo was reported in RCTs that examined amitriptyline (100mg/day), gabapentin (2.4 g/day), pregabalin (1200 mg/day), prosaptide (16 mg/day), peptide-T (6 mg/day), acetyl-L-carnitine (1g/day), mexilitine (600 mg/day), lamotrigine (600 mg/day) and topical capsaicin (0.075% q.d.s.).

CONCLUSIONS

Evidence of efficacy exists only for capsaicin 8%, smoked cannabis and rhNGF. However,rhNGF is clinically unavailable and smoked cannabis cannot be recommended as routine therapy. Evaluation of novel management strategies for painful HIV-SN is urgently needed.

Pharmacology and treatment of neuropathic pains

PURPOSE OF REVIEW

This review briefly discusses the definition and clinical presentation of neuropathic pain and highlights recent advances in the treatment of neuropathic pain.

RECENT FINDINGS

Recent publications have confirmed the efficacy of tricyclic antidepressants, gabapentin, pregabalin, opioids, and tramadol for various neuropathic pain conditions. Selective serotonin noradrenaline reuptake inhibitors have been found to reduce pain in painful neuropathy. The new anticonvulsant lacosamide may have some effect in painful polyneuropathy, whereas levetiracetam has failed to relieve postmastectomy and spinal cord injury pain. The role of the old anticonvulsant phenytoin is still unsettled. A recent trial has found an effect of cannabinoids also in peripheral neuropathic pain. Various topical treatments such as topical lidocaine, topically applied capsaicin in high concentrations (8%), and botulinum toxin have recently been shown to have a pain-relieving effect in various peripheral neuropathic pain conditions. Spinal cord and transcranial magnetic stimulation are stimulation therapies with some evidence for efficacy.

SUMMARY

Treating neuropathic pain remains a great challenge, and the treatment has to be individualized to the single patient, taking into account side effects, pain type, comorbidities, and drug interactions.

Acetyl-l-carnitine and nucleoside reverse transcriptase inhibitor-associated neuropathy in HIV infection

OBJECTIVES

Antiretroviral toxic neuropathy (ATN) is associated with dideoxynucleoside reverse transcriptase inhibitor use in patients infected with HIV, possibly as a result of mitochondrial toxicity. Acetyl-l-carnitine (ALC) has been linked to symptomatic improvement in ATN. We present an open-label single-arm pilot study to evaluate changes in intra-epidermal nerve fibre (IENF) density and mitochondrial DNA (mtDNA) copies/cell among subjects treated with 3000 mg ALC daily.

METHODS

Punch skin biopsies were examined at baseline and after 24 weeks of therapy. Participants reported neuropathic symptoms using the Gracely Pain Intensity Score. Neurological examinations were completed.

RESULTS

Twenty-one subjects completed the study. ALC was generally well tolerated. The IENF density did not change in cases completing 24 weeks of ALC therapy, with median (90% confidence interval) IENF changes of -1.70 (-3.50, infinity) (P=0.98) and 2.15 (-0.10, infinity) (P=0.11) for the distal leg and proximal thigh, respectively. Fat mtDNA copies/cell did not change with therapy. Improvements in neuropathic pain (P<0.01), paresthesias (P=0.01), and symptoms of numbness (P<0.01) were noted. Similarly, improvement was noted on the Gracely Pain Intensity Score.

CONCLUSIONS

ALC therapy coincided with improvements in subjective measures of pain in this open-label single-arm study. However, changes were not observed in objective measures of IENF density or mtDNA levels, providing little objective support for use of ALC in this setting.

Thioctic acid and acetyl-L-carnitine in the treatment of sciatic pain caused by a herniated disc: a randomized, double-blind, comparative study

BACKGROUND AND OBJECTIVE

Sciatica is a painful condition characterized by radiating leg pain that most commonly originates from a herniated disc in the lumbar or sacral spine. Although sciatic pain is typically self-limiting, pharmacological analgesic therapy forms the mainstay of treatment. Acetyl-L-carnitine (levacecarnine; ALC) is a naturally occurring substance that promotes peripheral nerve regeneration and has been shown to have analgesic effects in patients with peripheral neuropathies of diabetic, HIV-related or chemotherapeutic origin. Thioctic acid, a key compound in oxidative metabolism, has antioxidant properties that may help the recovery of nerve functionality and decrease neuropathic pain. This study aimed to compare, for the first time, the efficacy of oral treatment with ALC or thioctic acid in patients with peripheral neuropathic (sciatic) pain associated with a herniated disc.

METHODS

This was a randomized, double-blind trial conducted in a hospital setting. A total of 64 consecutive patients (mean age 61 years; range 29-85) with acute backache and moderate sciatica were recruited. Patients in group 1 (n = 33) received ALC 1180 mg/day; patients in group 2 (n = 31) received thioctic acid 600 mg/day. The study period was 60 days. The primary efficacy endpoint was change in clinical signs and symptoms of sciatica, as measured on the Neuropathy Impairment Score in the Lower Limbs (NIS-LL) questionnaire, the Neuropathy Symptoms and Change in the Lower Limbs (NSC-LL) questionnaire, and the Total Symptom Score (TSS) questionnaire. The secondary efficacy endpoint was improvement in neurological deficit (as measured by electromyography) compared with baseline.

RESULTS

Both treatments produced significant improvements from baseline in neuropathy on electromyography at day 60, and greater mean improvements were observed with thioctic acid (-0.19 +/- 0.29 vs baseline) than with ALC (-0.09 +/- 0.40 vs baseline), although the between-group difference was not statistically significant. Thioctic acid produced significantly greater mean improvements than ALC from baseline for NIS-LL (-2.52 +/- 1.50 vs -1.48 +/- 1.37, respectively), NSC-LL (-2.16 +/- 1.37 vs 1.42 +/- 1.37, respectively) and TSS (-1.90 +/- 1.08 vs 1.18 +/- 1.01, respectively) scores (p < 0.05 for all comparisons). More patients receiving thioctic acid than ALC reported a decreased need for analgesia (71.0% vs 45.5%, respectively; p < 0.05) and neither treatment impacted significantly on sleep quality.

CONCLUSIONS

Thioctic acid 600 mg/day appears to be at least as effective as ALC in the treatment of sciatic pain caused by a herniated disc and may be associated with an improvement in symptom scores and reduced need for analgesia. However, because of the limited number of patients evaluated and the lack of a placebo control in this trial, further studies are warranted in order to provide more definitive results.