The Effects of OP-1206 α-CD on Walking Dysfunction in the Rat Neuropathic Intermittent Claudication Model

Effect of epidural polydeoxyribonucleotide in a rat model of lumbar foraminal stenosis

Background

We aimed to investigate the effect of epidural polydeoxyribonucleotide (PDRN) on mechanical allodynia and motor dysfunction in a rat model of lumbar foraminal stenosis (LFS).

Methods

This study was conducted in two stages, using male Sprague-Dawley rats. The rats were randomly divided into eight groups. In the first stage, the groups were as follows vehicle (V), sham (S), and epidural PDRN at 5 (P5), 8 (P8), and 10 (P10) mg/kg; and in the second stage, they were as follows intraperitoneal PDRN 8 mg/kg, epidural 3,7-dimethyl-1-propargilxanthine (DMPX) (0.1 mg/kg), and DMPX (0.1 mg/kg). The LFS model was established, except for the S group. After an epidural injection of the test solutions, von Frey and treadmill tests were conducted for 3 weeks. Subsequently, histopathologic examinations were conducted in the V, S, P5, and P10 groups.

Results

A total of 65 rats were included. The P8 and P10 groups showed significant recovery from mechanical allodynia and motor dysfunction at all time points after drug administration compared to the V group. These effects were abolished by concomitant administration of DMPX. On histopathological examination, no epineurial inflammation or fibrosis was observed in the epidural PDRN groups.

Conclusions

Epidural injection of PDRN significantly improves mechanical allodynia and motor dysfunction in a rat model of LFS, which is mediated by the spinal adenosine A_2A receptor. The present data support the need for further research to determine the role of epidural PDRN in spinal stenosis treatment.

Optimal treatment for lumbar spinal stenosis: an update

PURPOSE OF REVIEW

Our review of current literature within the past 12-24 months for the treatment of lumbar spinals stenosis (LSS) serves to update providers on recent advances and comparisons regarding therapy spanning lifestyle modification, pharmacologic therapy, minimally invasive interventions, and surgical interventions.

RECENT FINDINGS

Current literature supporting the inclusion of physical therapy and gabapentin/pregabalin within an initial treatment regimen have been positive. A recent randomized, double-blinded clinical trial of adding calcitonin to epidural steroid injections have shown improvement in pain and function up to 1 year. The minimally invasive lumbar decompression (mild) procedure is showing ongoing beneficial results in pain and function. Spinal cord stimulation (SCS) may have a role for select patients with lumbar spinal stenosis. Finally, the benefits of surgical treatment versus nonsurgical treatment is ultimately inconclusive because of the nature of data collection, inconsistencies with the clinical definition of LSS, and a lack of standardized treatment guidelines.

SUMMARY

Our review of current research demonstrates there is a positive role for the current conservative therapies, with favorable results for interventions such as minimally invasive decompression and SCS. Pharmacologic interventions such as systemic prostaglandin analogues and epidural agents such as calcitonin demonstrate early promise, but need to undergo additional safety testing and confirmatory trials. Further long-term research with validated, objective measurements for the aforementioned treatments are needed to draw any definitive conclusions for clinical practice.

Comparative study of the efficacy of limaprost and pregabalin as single agents and in combination for the treatment of lumbar spinal stenosis: a prospective, double-blind, randomized controlled non-inferiority trial

BACKGROUND CONTEXT

Although the simultaneous management of neuronal ischemia-related pain and compression-demyelination-related neuropathic pain is considered optimal in treating lumbar spinal stenosis (LSS), the effect of combination therapy with pregabalin and limaprost has not been elucidated.

PURPOSE

This study aimed to compare the effects of limaprost and pregabalin individually and in combination for the treatment of LSS.

STUDY DESIGN

This is a prospective, double-blind, double-dummy, randomized controlled trial.

PATIENT SAMPLE

The sample consists of patients with LSS.

OUTCOME MEASURES

The baseline-adjusted Oswestry Disability Index (ODI) score, visual analog scale (VAS) scores for leg pain, the European Quality of Life-5 dimensions (EQ-5D), and initial claudication distance (ICD).

METHODS

The present study (ClinicalTrials.gov, number NCT01888536) was a prospective, double-blind, double-dummy, randomized controlled trial designed to determine the efficacy of limaprost in alleviating leg pain, improving disability, and increasing walking distance in persons with degenerative LSS in three different treatment groups: limaprost alone, pregabalin alone, and combined limaprost and pregabalin through 1:1:1 allocation. The primary outcome was the baseline-adjusted ODI score at 8 weeks after treatment. The non-inferior margin of the ODI was set at δ=10 points.

RESULTS

The baseline-adjusted ODI score (primary outcome) at 8 weeks after treatment in the limaprost group was not inferior to those in the pregabalin and limaprost+pregabalin groups. The overall changes of the baseline-adjusted ODI scores, VAS scores for leg pain, the EQ-5D, and ICD during the follow-up assessments over an 8-week period (secondary end point) were not different among the three groups. The baseline-adjusted ODI scores and VAS scores for leg pain decreasedsignificantly over time after treatment in all three groups. The baseline-adjusted EQ-5D score and ICD also increased significantly over time after treatment in all three groups.

CONCLUSIONS

The efficacy of limaprost for lumbar spinal stenosis was not inferior compared with that of pregabalin or the combination of limaprost and pregabalin in terms of disability. Therefore, combined treatment with limaprost and pregabalin does not provide additional relief in symptoms in patients with LSS compared with monotherapy with limaprost or pregabalin.

Prostaglandin E1 Treatment for Lumbar Spinal Canal Stenosis: Review of the Literature

BACKGROUND

The important pathophysiologic factor of neurogenic intermittent claudication (NIC) in lumbar spinal canal stenosis (LSCS) has been reported to be the reduction in intraneural blood flow and a state of relative ischemia in nerve tissues. Prostaglandin E1 (PGE1) presumably improves symptoms in patients with LSCS by improving the blood flow in the cauda equina and nerve roots through its vasodilation and antiplatelet aggregation effects. The purpose of the study was to summarize the results of previous studies regarding PGE1 treatment for LSCS and to describe the details of PGE1 treatment to all physicians who take care of patients with LSCS.

METHODS

Review of the literature.

RESULTS

There are 3 PGE1-related products that have been used clinically for the treatment of LSCS: PGE1, lipo-PGE1, and limaprost (PGE1 derivative). Experimental studies have been performed to verify the efficacy of PGE1 treatment for LSCS. Many studies have reported clinical outcomes of PGE1 treatment in patients with LSCS. Overall, previous studies examining PGE1 treatment for LSCS demonstrate improvement in several clinical outcome measures such as the visual analog scale, Japanese Orthopaedic Association score, and NIC distance, although most of the studies have only short-term follow-up.

CONCLUSIONS

Based on the results of previous studies, PGE1 treatment may be an option as a conservative treatment for LSCS. However, future studies with high-quality and long-term follow-up are necessary. Future studies also should include refinement of indications, administration period, as well as comparisons between PGE1 treatment and other conservative treatments such as epidural injection.

Effects of goshajinkigan, hachimijiogan, and rokumigan on mechanical allodynia induced by Paclitaxel in mice

Peripheral neuropathy is a major dose-limiting side effect of the chemotherapeutic agent paclitaxel. This study examined whether the three related traditional herbal formulations, goshajinkigan (GJG; 牛車腎氣丸 Niú Chē Shèn Qì Wán), hachimijiogan (HJG; 八味地黃丸 Bā Wèi Dì Huáng Wán), and rokumigan (RMG; 六味丸 Liù Wèi Wán), would relieve paclitaxel-induced mechanical allodynia in mice. A single intraperitoneal injection of paclitaxel (5 mg/kg) induced mechanical allodynia, which peaked on day 14 after injection. On day 14 after paclitaxel injection, oral administration of GJG (0.1-1.0 g/kg) produced a significant inhibition of established allodynia, but HJG and RMG did not affect the allodynia. Repeated oral administration of GJG (0.1-1.0 g/kg) starting from the day after paclitaxel injection did not affect allodynia development, but significantly inhibited allodynia exacerbation. Repeated oral administration of HJG produced a slight inhibition of allodynia exacerbation, but that of RMG did not. These results suggest that prophylactic administration of GJG is effective in preventing the exacerbation of paclitaxel-induced allodynia. The herbal medicines Plantaginis Semen (車前子 Chē Qián Zǐ) and Achyranthis Radix (牛膝 Niú Xī), which are present in GJG but not in HJG, may contribute to the inhibitory action of GJG on the exacerbation of paclitaxel-induced allodynia.

The effect of a prostaglandin E1 derivative on the symptoms and quality of life of patients with lumbar spinal stenosis

BACKGROUND

Quality of life (QOL) is a concern for patients with lumbar spinal stenosis (LSS). In this study, QOL was examined using the 5-item EuroQol (EQ-5D).

METHODS

QOL and activities of daily living (ADL) were surveyed for 91 patients who visited 18 medical institutions in our prefecture and were diagnosed with LSS-associated intermittent claudication. A second survey was performed after ≥6 weeks for 79 of the subjects to evaluate therapy with limaprost (an oral prostaglandin E1 derivative) or etodolac (an NSAID). Symptoms, maximum walking time, QOL, ADL items, and relationships among these variables were investigated for all 91 patients. Leg pain, leg numbness, and low back pain while walking were surveyed by use of VAS scores (0-100).

RESULTS

Leg pain, leg numbness, and low back pain while walking (VAS ≥25) were present in 83.5, 62.6, and 54.9 % of the patients in the first survey, and approximately half of the patients had a maximum walking time <15 min. The mean EQ-5D utility value for QOL was 0.59 ± 0.12. This value was significantly associated with maximum walking time (p = 0.030) based on classification of patients into groups with walking times <7.5, 7.5-15, 15-30, and >30 min, showing that maximum walking time affected health-related QOL. Of the 79 patients who completed the second survey, 56 had taken limaprost and 23 (control group) had received etodolac. Limaprost improved possible walking time, reduced ADL interference, and significantly increased the EQ-5D utility score, whereas no significant changes occurred in the control group. Maximum walking time was prolonged by ≥10 min and the EQ-5D utility value was improved by ≥0.1 points in significantly more patients in the limaprost group than in the control group.

CONCLUSION

According to the findings of this survey, at an average of 8 weeks after administration limaprost improved symptoms, QOL, and ADL in LSS patients whereas treatment with an NSAID reduced pain but did not have any other effects.

Blood flow analysis of compressed nerve root after intravenous injection of lipo-prostaglandin E1

Prostaglandin E(1) (PGE(1)) is a potent vasodilator as well as an inhibitor of platelet aggregation and has therefore attracted interest as a therapeutic drug for lumbar canal stenosis. However, investigations in the clinical setting have shown that PGE(1) is effective in some patients but not in others, although the reason for this is unclear. The aim of the present study was to measure changes in intraradicular blood flow after intravenous injection of lipo-PGE(1) (0.15 microg/kg) using a laser Doppler flow meter in control model and nerve root compression model. Then, the nerve root in which blood flow was measured was removed and examined histologically. Intravenous injection of lipo-PGE(1) also resulted in marked increase of blood flow in the uncompressed nerve roots of the control group, but caused minimal enhancement of blood flow at the sites of nerve root compression exhibiting Wallerian degeneration. It is concluded that lipo-PGE(1) has less effect on markedly degenerated nerve roots than it does on those that are normal.

The efficacy of prostaglandin E1 derivative in patients with lumbar spinal stenosis

STUDY DESIGN

Randomized controlled trial.

OBJECTIVE

To examine the effect of limaprost, an oral prostaglandin (PG) E1 derivative, on health-related quality of life (HRQOL) in patients with symptomatic lumbar spinal stenosis (LSS), compared to etodolac, a NSAID.

SUMMARY OF BACKGROUND DATA

Limaprost, an oral PGE1 derivative, was developed in Japan to treat numerous ischemic symptoms of thromboangiitis obliterans (TAO) and LSS. Previous studies have demonstrated the effectiveness of limaprost in the symptoms in patients with LSS. However, the evidence for effect on patient-reported outcomes, such as patient's HRQOL or satisfaction, is limited.

METHODS

This study was conducted at 4 study sites in Japan. Briefly, inclusion criteria were: age between 50 and 85 years; presence of both neurogenic intermittent claudication (NIC) and cauda equina symptoms (at least presence of bilateral numbness in the lower limbs); and MRI-confirmed central stenosis with acquired degenerative LSS. Limaprost (15 microg/d) or etodolac (400 mg/d) was administered for 8 weeks. The primary outcome was Short Form (SF)-36, and the secondary outcomes were the verbal rating scale of low back pain and leg numbness, walking distance, subjective improvement, and satisfaction.

RESULTS

A total of 79 participants were randomized (limaprost:etodolac = 39:40). Thirteen participants withdrew from the study (limaprost:etodolac = 5:8) and 66 completed the study (limaprost:etodolac = 34:32). Comparisons showed that limaprost resulted in significantly greater improvements in the SF-36 subscales of physical functioning, role physical, bodily pain, vitality, and mental health. Limaprost was also significantly better than etodolac for leg numbness, NIC distance, and subjective improvement and satisfaction. In the subgroup analysis stratified by symptom severity, limaprost seemed more effective for milder symptoms. No serious adverse effects were reported in either treatment group.

CONCLUSION

In this study, limaprost was found to be efficacious on most outcome measures, such as HRQOL, symptoms and subjective satisfaction, in LSS patents with cauda equina symptoms.

The effects of cilostazol on nerve conduction velocity and blood flow: acute and chronic cauda equina compression in a canine model

STUDY DESIGN

Analyses of improvements in nerve conduction velocity (NCV) and blood flow after administering cilostazol in a dog model of experimental acute and chronic cauda equina compression.

OBJECTIVE

To determine whether cilostazol improves NCV and blood flow, and cilostazol inhibits blood clots in capillaries of nerve roots after cauda equina compression.

SUMMARY AND BACKGROUND DATA

Reduction in blood flow is an important factor in neurogenic intermittent claudication for lumbar spinal stenosis. Prostaglandin E1 (PGE1) and calcitonin have been reported to improve blood flow and neurogenic intermittent claudication in clinical and experimental studies. Cilostazol affects vasodilator and antiplatelet activity, and protects endothelial cells in blood vessels.

METHODS

Experimental groups in the acute compression study (n = 40) were divided into 4 treatment groups. Low-dose (3 microg/kg/min), medium-dose (10 microg/kg/min), or high-dose (30 microg/kg/min) cilostazol or a control vehicle were administered intravenously after cauda equina compression. NCV and blood flow were measured during the observation period (n = 20 measurements for each). Another 12 animals were used to evaluate chronic compression. Cilostazol was administered for 6 days orally 1 day after compression treatment group (n = 6); the nontreatment group (n = 6) did not receive any drug. NCV was measured immediately after and 7 days after compression. Blood flow was measured 7 days after compression.

RESULTS

In the acute compression study, NCV in the medium-dose group was significantly higher than that in the other groups during the compression period (P < 0.05). During the recovery period, there was no significant difference in NCV among groups. In the chronic compression study, NCV and blood flow in the cilostazol group were significantly higher than those in the control group (P < 0.05).

CONCLUSION

Cilostazol improved NCV and blood flow to the cauda equina in this dog model. Cilostazol might be a potential agent to improve symptoms due to compression of cauda equina and/or cauda equina dysfunction.

Activation of extracellular signal-regulated protein kinase in dorsal horn neurons in the rat neuropathic intermittent claudication model

Extracellular signal-regulated protein kinase (ERK) is a mitogen-activated protein kinase (MAPK) that mediates several cellular responses to mitogenic and differentiation signals, and activation of ERK in dorsal horn neurons by noxious stimulation is known to contribute to pain hypersensitivity. In order to elucidate the pathophysiological mechanisms of the cauda equina syndrome, secondary to spinal canal stenosis, we evaluated walking dysfunction triggered by forced exercise and activation of ERK in the dorsal horn using a rat model of neuropathic intermittent claudication. Rats in the lumbar canal stenosis (LCS) group showed a shorter running distance from 1 to 14 days after surgery. Two minutes after running on the treadmill apparatus, phosphorylation of ERK was induced in neurons in the superficial laminae in the LCS group but not in the sham group, whereas there was no change in the deeper laminae. Intrathecal administration of the MAPK kinase inhibitor, U0126, 30 min before running, clearly increased the running distance, whereas there was no significant change in the vehicle control group 3 days after surgery. In addition, a prostaglandin E1 analog, OP-1206 alpha-CD, administered orally, improved the walking dysfunction, and further, inhibited activation of ERK following running 7 days after surgery. These findings suggest that intermittent claudication triggered by forced walking might affect the phosphorylation of ERK in the superficial laminae, possibly via transient (partial) ischemia of the spinal cord. ERK activation in the dorsal horn neurons may be involved in the transient pain in the neuropathic intermittent claudication model.

Effects of OP-1206 alpha-CD on walking dysfunction in the rat neuropathic intermittent claudication model: comparison with nifedipine, ticlopidine and cilostazol

The systemic treatment effects of OP-1206 alpha-CD (17S-20-dimethyl-trans-delta 2-PGE1 alpha-cyclodextrin clathrate), a prostaglandin E1 (PGE1) analogue, on walking dysfunction, spinal cord blood flow (SCBF) and skin blood flow (SKBF) were assessed in the rat neuropathic intermittent claudication (IC) model in comparison with nifedipine (dimethyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylate), ticlopidine (5-[(2-chlorophenyl)methyl]-4,5,6,7-tetrahydrothieno[3,2-C]pyridine hydrochloride) and cilostazol (6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)-butoxy]-3,4-dihydro-2(1H)-quinolinone). Two pieces of silicone rubber strips were placed in the lumbar (L4 and L6) epidural space in rats. After surgery, walking function was measured using a treadmill apparatus. SCBF and SKBF were measured using a laser-Doppler flow meter. Drugs were administered orally twice a day for 11 days from day 3 post-surgery. Treatment with OP-1206 alpha-CD significantly improved walking dysfunction on days 5, 7 and 14, and improved SCBF on day 14 post-surgery. SKBF remained unaffected. Treatment with nifedipine, ticlopidine or cilostazol had no significant effects on any of the parameters measured in this model. These data suggest that the therapeutic effect of OP-1206 alpha-CD is primarily mediated by the improved local SCBF at the territory of spinal stenosis and not due to improvement of peripheral perfusion and/or antiplatelet activity.

Effects of orally administered OP-1206 alpha-CD with loxoprofen-Na on walking dysfunction in the rat neuropathic intermittent claudication model

An orally active prostaglandin E1 analogue, OP-1206 alpha-CD improves walking dysfunction in the rat spinal stenosis model. Loxoprofen-Na, a non-steroidal anti-inflammatory drug, is used to relieve chronic pain in patients with lumbar spinal canal stenosis. To determine whether the OP-1206 alpha-CD in combination with loxoprofen-Na could induce a greater therapeutical effect on walking dysfunction and spinal cord blood flow (SCBF) than OP-1206 alpha-CD treatment alone after chronic spinal stenosis in the rat. Spinal stenosis was induced by placing two pieces of silicon rubber strips in the lumbar (L4 and L6) epidural space of rats. After surgery, walking function was measured using a treadmill apparatus and SCBF was measured using a laser-Doppler flow meter. Drugs were administered orally twice a day for 11 days from the day 3 post-surgery. OP-1206 alpha-CD elicited a significant improvement of walking dysfunction on days 7 and 14 post-surgery and significantly increased spinal cord blood flow on day 15, whereas walking dysfunction and SCBF of rats treated with loxoprofen-Na alone remained unchanged. Combined treatment of OP-1206 alpha-CD with loxoprofen-Na did not provide additive therapeutical effect. These results suggest that a significant improvement seen after OP-1206 alpha-CD treatment is primarily mediated by improvement of the local spinal cord blood flow. This effect is not ameliorated or potentiated by a combined treatment with loxoprofen-Na.