Characterization of the potentiation of the antinociceptive effect of diclofenac by vitamin B complex in the rat

Mechanisms of action of vitamin B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) in pain: a narrative review

Pain is a complex sensory and emotional experience with nociceptive, nociplastic, and neuropathic components. An involvement of neurotropic B vitamins (B1 - thiamine, B6 - pyridoxine, and B12 - cyanocobalamin) as modulators of inflammation and pain has been long discussed. New evidence suggests their therapeutic potential in different pain conditions. In this review, we discuss the main role of neurotropic B vitamins on different nociceptive pathways in the nervous system and to describe their analgesic action mechanisms. The performed literature review showed that, through different mechanisms, these vitamins regulate several inflammatory and neural mediators in nociceptive and neuropathic pain. Some of these processes include aiming the activation of the descending pain modulatory system and in specific intracellular pathways, anti-inflammatory, antioxidative and nerve regenerative effects. Moreover, recent data shows the antinociceptive, antiallodynic, and anti-hyperalgesic effects of the combination of these vitamins, as well as their synergistic effects with known analgesics. Understanding how vitamins B1, B6, and B12 affect several nociceptive mechanisms can therefore be of significance in the treatment of various pain conditions.

Food for Special Medical Purposes and Nutraceuticals for Pain: A Narrative Review

Introduction

The present paper focuses on the possible contribution of food compounds to alleviate symptomatic pains. Chronic pain can more easily be linked to anticipatory signals such as thirst and hunger than it is to sensory perceptions as its chronicity makes it fall under the behavioural category rather than it does senses. In fact, pain often negatively affects one’s normal feeding behavioural patterns, both directly and indirectly, as it is associated with pain or because of its prostrating effects.

Nutritional Compounds for Pain

Several nutraceuticals and Foods for Special Medical Purposes (FSMPs) are reported to have significant pain relief efficacy with multiple antioxidant and anti-inflammatory properties. Apart from the aforementioned properties, amino acids, fatty acids, trace elements and vitamins may have a role in the modulation of pain signals to and within the nervous system.

Conclusion

In our opinion, this review could be of great interest to clinicians, as it offers a complementary perspective in the management of pain. Trials with well-defined patient and symptoms selection and a robust pharmacological design are pivotal points to let these promising compounds become better accepted by the medical community.

Synergistic interaction between B vitamins and statins to counter nociception in rats

Evidence suggests that the antinociceptive activity of various drugs can be increased when administered in combination with B vitamins (BVs). The aim of this study was to examine the potential interaction between statins and BVs to counter nociception, the latter measured by the formalin test. Rats were orally administered atorvastatin (1, 3, 10 and 30 mg/kg), pravastatin (1, 3, 10 and 30 mg/kg), rosuvastatin (1, 3, 10 and 30 mg/kg), BVs (31, 56, 100 and 180 mg/kg) or calculated combinations of BVs with each drug. The effective dose 30 (ED₃₀ ) was calculated for each statin and BVs and subjected to isobolographic analysis, thus finding the ED₃₀ of the combinations. The antinociceptive experimental ED₃₀ values for BVs administered with atorvastatin, pravastatin or rosuvastatin were 1.53 ± 0.38, 6.74 ± 0.04 and 4.26 ± 0.39, respectively, being lower (p < .05) than the corresponding theoretical ED₃₀ : 28.02 ± 2.20, 28.17 ± 2.20 and 29.86 ± 2.21. Since BVs likely boost the antinociceptive effect of statins, these combinations could possibly be advantageous in pain management.

Effect of Photobiomodulation (Diode 810 nm) on Long-Standing Neurosensory Alterations of the Inferior Alveolar Nerve: A Case Series Study

Objective: To evaluate and describe the results of photobiomodulation (PBM) therapy on the treatment of long-standing neurosensory inferior alveolar nerve (IAN) alterations after third molar extraction. Background: The use of PBM is an acceptable alternative method to improve the therapeutic outcomes of neural lesions. Materials and methods: Longitudinal case study research. Patients with >6 months of inferior alveolar neurosensory disturbance after third molar extraction were included. Fifteen laser sessions were done, irradiating intra- and extraoral points along the distribution of this nerve area. A semiconductor Ga,Al,As diode laser (Thor laser^®) was used. Before and after the treatment, variables such as Zuniga-Essick score, British Medical Research Council (BRC) scale, visual analog scale (VAS), and mapping of the affected area were described. Gender, age, and duration of the lesion were analyzed. Descriptive statistical study was carried out with SPSS 19.0. Results: Eleven patients with a mean age of 38.5 years [standard deviation (SD) ±15.22]. Average duration of the lesion was 13.2 (SD ±4) months. The results obtained with the Zuniga-Essick scale before treatment showed mild alteration in 36.3% (4), moderate in 18.2% (2), and severe in 45.4% (5). After treatment, the percentage score improved, obtaining normality in 54.5% (6) of the patients and mild degree in 27.2% (3). In the BRC score, before the treatment, 45.4% (5) of grade S2+ and 27% (3) of S3 and S3+ were obtained. The final percentage after treatment reached an improvement of S4 in a total of 36% (4) of cases and a recovery of S3+ in 54.5% (6). Reduction of the mapped altered area and an upturn of VAS were noted. Conclusions: The laser parameters and application protocol used result in subjective and objective improvement in mechanical sensory perception in long-standing neurosensory deficit in the IAN.

Therapy for acute nonspecific back pain: new additional opportunities

Information about a favorable prognosis for a patient, recommendations for activities, and optimal pharmacotherapy are a mainstay in the effective treatment of acute nonspecific low back pain (NLBP). Standard pharmacotherapy for acute NLBP includes nonsteroidal anti-inflammatory drugs (NSAIDs). However, the longer their administration and larger doses, the higher the risk of side effects are. NSAIDs are contraindicated in some cases. In this connection, it has become necessary to search for new opportunities for the pharmacotherapy of acute NLBP. The results of experimental studies have demonstrated the analgesic and anti-inflammatory effects of high-dose B vitamins. Clinical trials have confirmed the efficacy of vitamin B complex (thiamine, pyridoxine, and cyanocobalamin) in the treatment of acute NLBP. The paper considers the practical significance of concomitant administration of B vitamins and NSAIDs in NLBP and notes the efficacy of milgamma used both alone and in combination with NSAIDs in the treatment of acute NLBP.

Long-Term Treatment by Vitamin B1 and Reduction of Serum Proinflammatory Cytokines, Hyperalgesia, and Paw Edema in Adjuvant-Induced Arthritis

INTRODUCTION

Immune system is involved in the etiology and pathophysiology of inflammation and vitamins are important sources of substances inducing nonspecific immunomodulatory effects. Given the proinflammatory role of cytokines in the inflammation and pain induction, this study aimed to assess the effects of long-term administration of vitamin B₁ on the proinflammatory cytokines, edema, and hyperalgesia during the acute and chronic phases of adjuvant-induced arthritis.

METHODS

On the first day of study, inflammation was induced by intraplantar injection of complete Freund's adjuvant (CFA) in the hindpaws of rats. Vitamin B₁ at doses of 100, 150, and 200 mg/kg was administrated intraperitoneally during 21 days of the study. Antinociceptive and anti-inflammatory effects of vitamin B₁ were also compared to indomethacin (5 mg/kg). Inflammatory symptoms such as thermal hyperalgesia and paw edema were measured by radiant heat and plethysmometer, respectively. Serum TNF-α and IL-1β levels were checked by rat standard enzyme-linked immune sorbent assay (ELISA) specific kits.

RESULTS

The results indicated that vitamin B₁(150 and 200 mg/kg) attenuated the paw edema, thermal hyperalgesia, and serum levels of TNF-α and IL-1β during both phases of CFA-induced inflammation in a dose-dependent manner. Effective dose of vitamin B₁(150 mg/kg) reduced inflammatory symptoms and serum levels of TNF-α and IL-1β compare to indomethacin during the chronic phase of inflammation.

CONCLUSION

Anti-inflammatory and antihyperalgesic effects of vitamin B1 during CFA-induced arthritis, more specifically after chronic vitamin B₁ administration, suggest its therapeutic property for inflammation.

Comparative effectiveness of B and e vitamins with diclofenac in reducing pain due to osteoarthritis of the knee

Background:

Knee osteoarthritis is one of the most prevalent chronic disorders. Several pharmacological and non pharmacological approaches are used to treat this disease. Today, the effect of B and E vitamins on rheumatology diseases is being discussed. In this study, the efficacy of B and E vitamins accompanied with diclofenac on pain relief in patients with knee osteoarthritis was investigated and compared.

Methods:

In this double-blinded clinical trial, 120 patients with knee osteoarthritis referring training Rheumatology and Orthopedics Clinic of Shahrekord University of Medical sciences were investigated. Of these patients, 12 were excluded throughout the study. The patients underwent treatment in three groups (oral diclofenac + oral B vitamin, oral diclofenac + oral vitamin E, and oral diclofenac + placebo). Pain relief was assessed by visual analogue scale (VAS) questionnaire and morning stiffness and physical function were assessed by WOMAC standard questionnaire at three times; the first examination, two weeks, and three weeks after referring.

Results:

The mean score of WOMAC questionnaire at VASs of knee pain, total pain severity, knee joint stiffness, and function of the last 48 hours decreased significantly in all three groups (diclofenac, E and B vitamins) from the first to third examination (P<0.001). Decrease in VAS of knee pain and function of the last 48 hours was higher in B vitamin group than the diclofenac and E vitamin group (P=0.008) and decrease in total pain severity was reported higher in B vitamin group than E vitamin and diclofenac group (P=0.019). Decrease in knee joint stiffness underwent a similar trend in the three groups.

Conclusion:

In view similar analgesic and anti-inflammatory properties, as well as very few, non prevalent complications of B and E vitamins, use of two or more drugs with a different mechanism of effect seems necessary to enhance their effect on osteoarthritis treatment.

A randomized, clinical trial of ketorolac tromethamine vs ketorolac trometamine plus complex B vitamins for cesarean delivery analgesia

Background:

Ketorolac is widely used for postoperative analgesia in patients who undergo cesarean delivery. In countries where the use of opioids is considerably restricted, alternatives to narcotics are required.

Aim:

We hypothesize that the addition of complex B synergize the analgesic effect of ketorolac in postoperative cesarean patients, thus requiring a smaller dose of the anti-inflammatory agent, and therefore decreasing the potential side effects of ketorolac.

Methods:

A randomized clinical trial with 100 patients undergoing a primary elective cesarean delivery enrolled in the study. Pain was assessed in the recovery room and then they were randomized to receive ketorolac 30 mg intramuscular (i.m.) or 15 mg of ketorolac plus complex B vitamin (CBV). The pain score with an analog scale was assessed 1, 2, 6, 12, 18, and 24 h after the baseline. The student's t test was performed to compare the demographic differences between the 2 means.

Results:

100 patients were included in the study, showing no statistical differences in the demographics. The patient's pain score at 1, 2, 6, 12, 18 and 24 hours showed no statistical differences between the control group (ketorolac 30mg) compared to the group of ketorolac 15mg and complex B vitamins. No changes in the coagulation studies were found in both groups.

Conclusion:

The present study demonstrates that ketorolac 30 mg and ketorolac 15 mg plus complex B vitamins can provide acceptable analgesia in many patients with severe pain.

Assessing carrageenan-induced locomotor activity impairment in rats: comparison with evoked endpoint of acute inflammatory pain

BACKGROUND

Most animal models currently used to evaluate antinociceptive efficacy of analgesics rely on the assessment of evoked pain behaviours as primary endpoints.

METHODS

Here, we have developed and characterized the carrageenan-induced locomotor activity impairment (CLAIM) model to objectively assess non-evoked inflammatory pain behaviour in rats. In this model, 100 µL of 1% carrageenan was subcutaneously injected into the plantar aspect of the right hind paw and exploratory behaviour in the novel testing chamber was recorded using an automated locomotor activity system.

RESULTS

Carrageenan-injected animals exhibited an exploratory behavioural deficit 2-7 h following injection compared to saline-injected animals. The severity of impairment was carrageenan dose related, and sensitive to the light intensity in the testing room. The effects of standard analgesics on CLAIM were examined 2 or 3 h following carrageenan injection. Diclofenac and ibuprofen, in a dose range exerting no effect on locomotor activity in naïve rats, exhibited dose-related reversal of CLAIM (ED(50) = 1.5 and 5.0 mg/kg, respectively), with comparable efficacy on carrageenan-induced thermal hyperalgesia (ED(50) = 2.0 and 6.0 mg/kg, respectively). Gabapentin and duloxetine produced no reversal of CLAIM, or attenuation of thermal hyperalgesia. Efficacy discrepancy was noted for morphine on thermal hyperalgesia and CLAIM. Additionally, amphetamine dose dependently reversed CLAIM, and similarly increased locomotor activity in normal animals.

DISCUSSION AND CONCLUSION

The results presented here demonstrate that CLAIM provides an objective assessment of non-evoked pain behaviours for acute inflammatory pain. The pharmacological profile of standard analgesics supports that CLAIM model can be used to identify agents to treat acute inflammatory pain in the clinic.

Diclofenac plus B vitamins versus diclofenac monotherapy in lumbago: the DOLOR study

OBJECTIVES

To assess the influence of vitamins B1, B6 and B12 on the analgesia success achieved by diclofenac in subjects with acute lumbago.

RESEARCH DESIGN AND METHODS

A randomised, double blind controlled clinical study in parallel groups, in which subjects received twice-daily oral administration of either the combination therapy, Group DB (50 mg diclofenac plus 50 mg thiamine, 50 mg pyridoxine and 1 mg cyanocobalamin) or diclofenac monotherapy, Group D (50mg diclofenac). The study period lasted a maximum of 7 days. If sufficient pain reduction was achieved (defined as Visual Analogue Scale <20 mm and patient's satisfaction), subjects could withdraw from the treatment after 3 or 5 days. All subjects gave written informed consent to participate in the study.

MAIN OUTCOME MEASURES

The primary confirmatory study objective was to determine the number of patients with sufficient pain reduction after 3 days of treatment.

RESULTS

Three hundred and seventy-two subjects were allocated at random to either treatment group: Group DB - 187 subjects and Group D - 185 subjects. After 3 days of treatment, a statistically significant higher proportion of subjects in Group DB (n = 87; 46.5%) than in Group D (n = 55; 29%) terminated the study due to treatment success (chi(2): 12.06; p = 0.0005). Furthermore, the combination therapy yielded superior results in pain reduction, improvement of mobility and functionality. Drug safety monitoring profile throughout the trial was within the expected safety profile of diclofenac.

CONCLUSIONS

The combination of diclofenac with B vitamins was superior to diclofenac monotherapy in lumbago relief after 3 days of treatment. As a study drawback, daily VAS measurements were only recorded until subject withdrawal from treatment, whether after 3, 5, or 7 days. There were no differences in safety profile between the two study groups.

Characterization of the antinociceptive and anti-inflammatory activities of riboflavin in different experimental models

Riboflavin, similar to other vitamins of the B complex, presents anti-inflammatory activity but its full characterization has not yet been carried out. Therefore, we aimed to investigate the effect of this vitamin in different models of nociception, edema, fever and formation of fibrovascular tissue. Riboflavin (25, 50 or 100 mg/kg, i.p.) did not alter the motor activity of mice in the rota-rod or the open field models. The second phase of the nociceptive response induced by formalin in mice was inhibited by riboflavin (50 or 100 mg/kg). The first phase of this response and the nociceptive behavior in the hot-plate model were inhibited only by the highest dose of this vitamin. Riboflavin (25, 50 or 100 mg/kg, i.p.), administered immediately and 2 h after the injection of carrageenan, induced antiedema and antinociceptive effects. The antinociceptive effect was not inhibited by the pretreatment with cadmium sulfate (1 mg/kg), an inhibitor of flavokinase. Riboflavin (50 or 100 mg/kg, i.p., 0 and 2 h) also inhibited the fever induced by lipopolysaccharide (LPS) in rats. Moreover, the formation of fibrovascular tissue induced by s.c. implant of a cotton pellet was inhibited by riboflavin (50 or 100 mg/kg, i.p., twice a day for one week). Riboflavin (10 or 25 mg/kg, i.p.) also exacerbated the effect of morphine (2, 4 or 8 mg/kg, i.p.) in the mouse formalin test. In conclusion, the study demonstrates the antinociceptive and anti-inflammatory activities of riboflavin in different experimental models. These results, associated with the fact that riboflavin is a safe drug, is approved for clinical use and exacerbates the antinociceptive effect of morphine, may warrant clinical trials to assess its potential in the treatment of different painful or inflammatory conditions.

Direct determination of diclofenac in pharmaceutical formulations containing B vitamins by using UV spectrophotometry and partial least squares regression

This work proposes a simple and rapid analytical procedure for determination of diclofenac (DCF) in the presence of B vitamins, based on UV measurements and partial least squares (PLS). The interference of thiamine (THI) and pyridoxine (PYR) were modelled using an experimental design constructed in the ranges of 10-50 micromoll(-1) for DCF and THI and 15-75 micromoll(-1) for PYR. The procedure was repeated at five different pH values (between 3 and 6) and the best results were observed at pH 5, presenting a root mean square error of prediction (RMSEP) of 0.80 micromoll(-1) for DCF. The procedure was successfully applied to simultaneous determination of DCF, THI and PYR in synthetic mixtures and in a pharmaceutical formulation that contains a simple excipient (lactose). For determination of a more complex formulation that contains 15 different substances in the excipient, including some UV absorbing ones, the procedure was only able to determine DCF, since the excipient interferences disturbed THI and PYR predictions. Figures of merit, such as selectivity, analytical sensitivity, limit of detection and precision were determined for the DCF prediction model and the determinations were verified by an independent method, HPLC.

Riboflavin reduces hyperalgesia and inflammation but not tactile allodynia in the rat

Vitamin B2 (riboflavin) has been proposed as a prophylactic therapy of migraine. However, so far there are no preclinical studies about the analgesic properties of this vitamin. The current study was designed to investigate the possible antinociceptive, antihyperalgesic and antiallodynic effect of riboflavin in formalin, carrageenan-induced thermal hyperalgesia, and spinal nerve ligation models, respectively. Oral riboflavin produced a dose-related antinociceptive (6.25-50 mg/kg), antihyperalgesic (25-150 mg/kg) and anti-inflammatory (50-150 mg/kg) effect. Gabapentin (100 mg/kg, positive control), but not riboflavin (150-600 mg/kg), reduced tactile allodynia in neuropathic rats. Riboflavin-induced antinociception in the formalin test was reversed by pretreatment with NG-L-nitro-arginine methyl ester and glibenclamide, but not by NG-D-nitro-arginine methyl ester or naloxone. Our results indicate that riboflavin is able to produce antinociception and anti-inflammatory, but not antiallodynic, effect in the rat. The effect of riboflavin could be due to the activation of K+ channels or nitric oxide release, but not activation of opioid mechanisms.

Sildenafil increases diclofenac antinociception in the formalin test

The antinociceptive activity of an inhibitor of phosphodiesterase 5, alone or combined with diclofenac, was assessed in the formalin test. Local administration of diclofenac produced a significant antinociception in both phases of the formalin test in female Wistar rats. In contrast, 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [3,4-d]pyrimidin-5-yl)phenylsulfonyl]-4-methyl piperazine (sildenafil, an inhibitor of phosphodiesterase 5) produced significant antinociception, only during the second phase of the formalin test. Non-effective doses of sildenafil (25-100 microg/paw) significantly increased the antinociceptive effect of an inactive dose of diclofenac (25 microg) in both phases of the test. The antinociception produced by the drugs alone or the combination was due to a local action, as its administration in the contralateral paw was ineffective. Since sildenafil is a potent and selective inhibitor of phosphodiesterase 5, our results suggest that this drug produced its antinociceptive activity, and increased that of diclofenac, probably through the inhibition of cyclic GMP degradation.