Interference-free determination of carbamazepine in human serum using high performance liquid chromatography: a comprehensive research with three-way calibration methods

In the present study, a comprehensive and systematic strategy was described to evaluate the performance of several three-way calibration methods on a bio-analytical problem. Parallel factor analysis [PARAFAC], alternating trilinear decomposition [ATLD], self-weighted alternating trilinear decomposition [SWATLD], alternating penalty trilinear decomposition [APTLD], and unfolded partial least squares combined with the residual bilinearization procedure [U-PLS/RBL] were applied on high performance liquid chromatography with photodiode-array detection [HPLC-DAD] data to quantify carbamazepine [CBZ] in different serum samples. Using the proposed approach, successfully quantification of CBZ in human plasma, even in the presence of diverse uncalibrated serious interfering components was achieved. Moreover, the accuracy and precision of each algorithm for analyzing CBZ in serum samples were compared using root mean square error of prediction [RMSEP], the recovery values and figures of merits and reproducibility of the analysis. Satisfying recovery values for the analyte of interest were obtained by HPLC-DAD on a Bonus-RP column using an isocratic mode of elution with acetonitrile/K2HPO4 [pH = 7.5] buffer solution [45:55] coupled with second-order calibrations. Decreas of the analysis time and less solvent consumption are some of the pluses of this method. The analysis of real samples showed that the modeling of complex chromatographic profiles containing CBZ as the target drug using any of the mentioned algorithms can be potentially benefit drug monitoring in therapeutic research

Minocycline effects on IL-6 concentration in macrophage and microglial cells in a rat model of neuropathic pain

Background: Evidence indicates that neuropathic pain pathogenesis is not confined to changes in the activity of neuronal systems but involves interactions between neurons, inflammatory immune and immune-like glial cells. Substances released from immune cells during inflammation play an important role in development and maintenance of neuropathic pain. It has been found that minocycline suppresses the development of neuropathic pain. Here, we evaluated the analgesic effect of minocycline in a chronic constriction injury [CCI] model of neuropathic pain in rat and assessed IL-6 concentration from cultured macrophage and microglia cells

Methods: Male Wistar rat [n=6, 150-200 g] were divided into three different groups: 1] CCI+vehicle, 2] sham+vehicle, and 3] CCI+drug. Minocycline [10, 20, and 40 mg/kg] was injected one hour before surgery and continued daily to day 14 post ligation. Von Frey filaments and acetone, as pain behavioral tests, were used for mechanical allodynia and cold allodynia, respectively. Experiments were performed on day 0 [before surgery] and days 1, 3, 5, 7, 10, and 14 post -injury. At day 14, rats were killed and monocyte-derived macrophage from right ventricle and microglia from lumbar part of the spinal cord were isolated and cultured in RPMI and Leibovitz's media, respectively. IL-6 concentration was evaluated in cell culture supernatant after 24 h

Results: Minocycline [10, 20, and 40 mg/kg] attenuated pain behavior, and a decrease in IL-6 concentration was observed in immune cells compared to CCI vehicle-treated animals

Conclusion: Minocycline reduced pain behavior and decreased IL-6 concentration in macrophage and microglial cells

Paroxetine attenuates the development and existing pain in a rat model of neurophatic pain

P2X4 receptor [P2X4R], a purinoceptor expressed in activated spinal microglia, plays a key role in the pathogenesis of neuropathic pain. Spinal nerve injury induces up-regulation of P2X4R on activated microglia in the spinal cord, and blockade of this receptor can reduce neuropathic pain. The present study was undertaken to determine whether paroxetine, an inhibitor of P2X4R, could attenuate allodynia and hyperalgesia in chronic constriction injury [CCI] model of neuropathic pain when used preemptively or after the sciatic nerve injury. Male Wistar rats [150-200 g, n = 6] were divided into 3 different groups: 1- CCI vehicle-treated group, 2- Sham group, and 3- CCI paroxetine-treated group. Paroxetine [10 mg/kg, i.p.] was administered 1 h before surgery and continued daily until day 14. In other part of the study, paroxetine [10 mg/kg, i.p.] was administered at day 7 post injury and continued daily until day 14. von Frey filaments for mechanical allodynia and analgesia meter for thermal hyperalgesia were used to assay pain behavior. In a preventive paradigm, paroxetine significantly attenuated both mechanical allodynia and thermal hyperalgesia [P<0.001]. A significant decrease in pain behavior was seen with paroxetine on existing allodynia [P<0.001] and hyperalgesia [P<0.01] when initiated at day 7 post injury. It seems that paroxetine can attenuate pain behavior when administered before and also after sciatic nerve injury in CCI model of neuropathic pain

The Attenuation of Pain Behavior and Serum COX-2 Concentration by Curcumin in a Rat Model of Neuropathic Pain

BACKGROUND: Neuropathic pain is generally defined as a chronic pain state resulting from peripheral and/or central nerve injury. There is a lack of effective treatment for neuropathic pain, which may possibly be related to poor understanding of pathological mechanisms at the molecular level. Curcumin, a therapeutic herbal extract, has shown to be effectively capable of reducing chronic pain induced by peripheral administration of inflammatory agents such as formalin. In this study, we aimed to show the effect of curcumin on pain behavior and serum COX-2 level in a Chronic Constriction Injury (CCI) model of neuropathic pain. METHODS: Wistar male rats (150-200 g, n = 8) were divided into three groups: CCI vehicle-treated, sham-operated, and CCI drug-treated group. Curcumin (12.5, 25, 50 mg/kg, IP) was injected 24 h before surgery and continued daily for 7 days post-surgery. Behavioral tests were performed once before and following the days 1, 3, 5, 7 after surgery. The serum COX-2 level was measured on day 7 after the surgery. RESULTS: Curcumin (50 mg/kg) decreased mechanical and cold allodynia (P < 0.001) and produced a decline in serum COX-2 level (P < 0.001). CONCLUSIONS: A considerable decline in pain behavior and serum COX-2 levels was seen in rat following administration of curcumin in CCI model of neuropathic pain. High concentration of Curcumin was able to reduce the chronic neuropathic pain induced by CCI model and the serum level of COX-2.

Enhancement of Antinociception by Co-administrations of Nefopam, Morphine, and Nimesulide in a Rat Model of Neuropathic Pain

BACKGROUND: Neuropathic pain is a chronic pain due to disorder in the peripheral or central nervous system with different pathophysiological mechanisms. Current treatments are not effective. Analgesic drugs combined can reduce pain intensity and side effects. Here, we studied the analgesic effect of nimesulide, nefopam, and morphine with different mechanisms of action alone and in combination with other drugs in chronic constriction injury (CCI) model of neuropathic pain. METHODS: Male Wistar rats (n = 8) weighing 150-200 g were divided into 3 different groups: 1- Saline-treated CCI group, 2- Saline-treated sham group, and 3- Drug-treated CCI groups. Nimesulide (1.25, 2.5, and 5 mg/kg), nefopam (10, 20, and 30 mg/kg), and morphine (1, 3, and 5 mg/kg) were injected 30 minutes before surgery and continued daily to day 14 post-ligation. In the combination strategy, a nonanalgesic dose of drugs was used in combination such as nefopam + morphine, nefopam + nimesulide, and nimesulide + morphine. Von Frey filaments for mechanical allodynia and acetone test for cold allodynia were, respectively, used as pain behavioral tests. Experiments were performed on day 0 (before surgery) and days 1, 3, 5, 7, 10, and 14 post injury. RESULTS: Nefopam (30 mg/kg) and nimesulide (5 mg/kg) blocked mechanical and thermal allodynia; the analgesic effects of morphine (5 mg/kg) lasted for 7 days. Allodynia was completely inhibited in combination with nonanalgesic doses of nefopam (10 mg/kg), nimesulide (1.25 mg/kg), and morphine (3 mg/kg). CONCLUSIONS: It seems that analgesic drugs used in combination, could effectively reduce pain behavior with reduced adverse effects.

Study of the intraplantar injection of lidocaine and morphine on pain perception and the influence of morphine dependence and withdrawal on lidocaine-induced analgesia in rats

Morphine and lidocaine are known to influence the perception of pain. The present study sought to determine the influence of local administration of morphine on lidocaine-induced analgesia in morphine non-dependent [MND], morphine dependent [MD] and morphine withdrawal [MW] animals. Adult male Wistar rats were divided into four groups: Control, MND, MD and MW rats. Lidocaine [0.5, 1 and 2%] and morphine [200, 400 and 800 micro g] were injected in the plantar surface of the right paw. MD animals received chronic oral morphine [0.1, 0.2, 0.3 and 0.4 mg/ml in their drinking water] for 20 days. Twenty four hours before experiment, the animals in the MW group were deprived of morphine in their drinking water [physical dependence was observed by precipitating an abstinence syndrome with naloxone 2 mg/kg i.p.]. Analgesia was assessed using hot-plate apparatus. Morphine [400 micro g] and lidocaine [2%] produce local analgesia in MND group. In MND rats, non-analgesic doses of each drug [200 micro g morphine and 1% lidocaine] were used in combination and produced analgesia. In MD animals, all doses of lidocaine produced analgesia, while in MW animals, it failed to produce analgesia. In this situation, local administration of morphine could eventually influence the analgesic effect of lidocaine. Opioid withdrawal is one of the most common problems in clinic. This study determined the analgesic effect of lidocaine in MW animals in which lidocaine had no analgesic effect. In this regard, local administration of morphine with combination of lidocaine could probably produce an effective analgesia