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Background: The aim of this experiment was to investigate a long-lasting local anesthetic bupivacaine combined with serotonin at inducing cutaneous antinociception., Methods: The skin antinociception, characterized by an inhibition of the cutaneous trunci muscle reflex (CTMR) following the pinprick on the dorsal skin of rats, was evaluated. The cutaneous antinociceptive effects of bupivacaine alone, serotonin alone, or bupivacaine co-injected with serotonin in a dose-dependent fashion were constructed, while the drug-drug interactions were evaluated by isobologram., Results: Subcutaneous serotonin, as well as the local anesthetic bupivacaine provoked dose-related cutaneous antinociception. On an equipotent basis (50% effective dose [ED 50 ]), the relative potency was bupivacaine (0.43 [0.37-0.50] μmol)>serotonin (1.27 [1.15-1.40] μmol) (p<0.01). At the equi-anesthetic doses (ED 75 , ED 50 and ED 25 ), the duration of bupivacaine was similar to that of serotonin at producing cutaneous antinociceptive effects. Co-administration of bupivacaine and serotonin displayed a synergistic antinociception., Conclusions: The preclinical data demonstrated that serotonin is less potent in eliciting cutaneous antinociceptive effects but has the similar duration of action, compared with bupivacaine. We also found a more significant depth of the sensory block with bupivacaine+serotonin than bupivacaine alone., (Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Macrolide antibiotics and azole fungicides are detected widely in the aquatic environment as a result of their increased use in humans and animal livestock disease and their incomplete removal by wastewater treatment plants. In most cases, ecotoxicological tests are performed by using individual chemical substances, but because of the coexistence of a number of chemicals in the environment, organisms are exposed to many chemicals simultaneously. Therefore, it is important to evaluate effects of chemical interactions, adding to potential hazards of individual chemical. Here, we investigated the synergetic effects of combined chemicals (the azole fungicide ketoconazole and either of two macrolide antibiotics, erythromycin and clarithromycin) in growth inhibition testing using Pseudokirchneriella subcapitata according to OECD Test guideline 201. Combination index plots, isobolograms, and curve-shift analyses revealed that the combination of macrolide antibiotic and ketoconazole at various ratios resulted in strong synergism that enhanced growth inhibition of P. subcapitata, suggesting the necessity of investigating potential hazard of combined chemicals for regulatory purposes., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objective: N-butane and n-pentane can both produce general anesthesia. Both compounds potentiate γ-aminobutyric acid type A (GABA A ) receptor function, but only butane inhibits N-methyl-d-aspartate (NMDA) receptors. It was hypothesized that butane and pentane would exhibit anesthetic synergy due to their different actions on ligand-gated ion channels., Study Design: Prospective experimental study., Animals: A total of four Xenopus laevis frogs and 43 Sprague-Dawley rats., Methods: Alkane concentrations for all studies were determined via gas chromatography. Using a Xenopus oocyte expression model, standard two-electrode voltage clamp techniques were used to measure NMDA and GABA A receptor responses in vitro as a function of butane and pentane concentrations relevant to anesthesia. The minimum alveolar concentrations (MAC) of butane and pentane were measured separately in rats, and then pentane MAC was measured during coadministration of 0.25, 0.50 or 0.75 times MAC of butane. An isobole with 95% confidence intervals was constructed using regression analysis. A sum of butane and pentane that was statistically less than the lower-end confidence bound isobole indicated a synergistic interaction., Results: Both butane and pentane dose-dependently potentiated GABA A receptor currents over the study concentration range. Butane dose-dependently inhibited NMDA receptor currents, but pentane did not modulate NMDA receptors. Butane and pentane MAC in rats was 39.4±0.7 and 13.7±0.4 %, respectively. A small but significant (p<0.03) synergistic anesthetic effect with pentane was observed during administration of either 0.50 or 0.75×MAC butane., Conclusions: Butane and pentane show synergistic anesthetic effects in vivo consistent with their different in vitro receptor effects., Clinical Relevance: Findings support the relevance of NMDA receptors in mediating anesthetic actions for some, but not all, inhaled agents., (Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Background: Emergence of chloroquine (CQ) resistance among different strains of Plasmodium falciparum is the worst catastrophe that has ever perplexed the dedicated efforts to eradicate malaria. This urged the scientists to search for new alternatives or sensitizers to augment its antiplasmodium effect., Materials and Method: In this experiment, the potential of embelin, isolated from Embelia ribes, to inhibit the growth and sensitize CQ action was screened using SYBRE-green-I based drug sensitivity and isobologram assays, respectively. Its effect on red blood cells stability was screened to assess its safety. To explore its molecular mechanism, its effect on plasmodial Hemozoin and the in vitro β-hematin formation was screened as well. Furthermore, its anti-oxidant activity was measured using the conventional in vitro tests and its molecular characters were obtained using Molispiration program., Results: The results showed that its anti-plasmodial effect was weaker than CQ but synergism was obtained when they were combined at ratios lower than 5:5 CQ/embelin. Furthermore, β-hematin formation was inhibited by embelin without showing any synergism after mixing with CQ., Conclusion: Overall, embelin is not ideal to be suggested as a conventional antiplasmodium but it has a potential to ameliorate CQ resistance. Furthermore, its action is not related to its impact on hemozoin formation. Further, investigations are recommended to illustrate its detailed mechanism of action. Abbreviation used: CQ-DV-PBS-HEPES: Chloroquine-Digestive vacuole-Phosphate-buffer-saline-4-(2-hydroxyethyl-1-piperazin-ethan-sulphoni-acid), EDTA: Ethylen-diamin-tetra-acetic-acid, g.m.wt: Gram molecular weight, cMCM: Complete-malaria-culture-medium, Hct: Hematocrite, PRBCs: Parasitized-redblood-cells, nRBCs: Normal-red-blood-cells, RT: Room temperature, IC: Inhibitory concentration, FIC: Fractional inhibitory concentration, iCM: Incomplete-culturemedium, BSA: Bovin serum albumin, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, DPPH: 2,2-diphenyl-1- picrylhydrazy, BHT: Butylatedhydroxyl-toleuen, PSA: Polar surface area, ClogP: Log partition coefficient (octanol/water), GPCR: G-protein-coupled-receptors, DMSO: Dimethylsulphoxide, NaOH: Sodium hydroxide., Competing Interests: There are no conflicts of interest.

Inhibition of α-glucosidase activity may suppress postprandial hyperglycemia. The inhibition kinetic analysis showed that apigenin reversibly inhibited α-glucosidase activity with an IC50 value of (10.5 ± 0.05) × 10(-6) mol L(-1), and the inhibition was in a noncompetitive manner through a monophasic kinetic process. The fluorescence quenching and conformational changes determined by fluorescence and circular dichroism were due to the formation of an α-glucosidase-apigenin complex, and the binding was mainly driven by hydrophobic interactions and hydrogen bonding. The molecular simulation showed that apigenin bound to a site close to the active site of α-glucosidase, which may induce the channel closure to prevent the access of substrate, eventually leading to the inhibition of α-glucosidase. Isobolographic analysis of the interaction between myricetin and apigenin or morin showed that both of them exhibited synergistic effects at low concentrations and tended to exhibit additive or antagonistic interaction at high concentrations.

Traditional Chinese medicine (TCM) is an important part of primary health care in Asian countries that has utilized complex herbal formulations (consisting 2 or more medicinal herbs) for treating diseases over thousands of years. There seems to be a general assumption that the synergistic therapeutic effects of Chinese herbal medicine (CHM) derive from the complex interactions between the multiple bioactive components within the herbs and/or herbal formulations. However, evidence to support these synergistic effects remains weak and controversial due to several reasons, including the very complex nature of CHM, misconceptions about synergy and methodological challenges to study design. In this review, we clarify the definition of synergy, identify common errors in synergy research and describe current methodological approaches to test for synergistic interaction. We discuss the strengths and weaknesses of these models in the context of CHM and summarize the current status of synergy research in CHM. Despite the availability of some scientific data to support the synergistic effects of multi-herbal and/or herb-drug combinations, the level of evidence remains low, and the clinical relevancy of most of these findings is undetermined. There remain significant challenges in the development of suitable methods for synergistic studies of complex herbal combinations.

Activation of opioid and cannabinoid receptors expressed in nociceptors induces effective antihyperalgesia. In this study, we examined whether combinations of opioid and cannabinoid receptor agonists directed at the injured site would enhance therapeutic effectiveness. Behavioral pharmacology experiments were performed to compare the effects of DAMGO, a selective agonist for μ-opioid receptor (MOR), ACPA, a specific agonist for CB1, and combinations of DAMGO and ACPA in attenuating complete Freund's adjuvant (CFA)-induced mechanical hyperalgesia in the rat hindpaw. DAMGO (1μg-1mg) or ACPA (1μg-2mg) was administered into the inflamed paw when mechanical hyperalgesia was fully developed. When administered individually, DAMGO and ACPA dose-dependently reversed the mechanical hyperalgesia. DAMGO displayed a lower ED50 value (57.4±2.49μg) than ACPA (111.6±2.18μg), but ACPA produced longer lasting antihyperalgesic effects. Combinations of DAMGO and ACPA also dose-dependently attenuated mechanical hyperalgesia, but the antihyperalgesic effects were partial and transient even at high doses. Using isobolographic analysis, we determined that combined treatment with DAMGO and ACPA produced antagonistic effects with the observed ED50 of 128.4±2.28μg. Our findings showed that MOR and CB1 agonists directed at the inflamed site effectively attenuate mechanical hyperalgesia when administered individually, but exert opposing effects when administered together. The antagonistic interactions between the two classes of drugs at the inflamed site suggest distinct mechanisms unique to peripheral nociceptors or inflamed tissue, and therefore require further studies to investigate whether the therapeutic utility of the combined drug treatments in chronic pain conditions can be optimized., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The main goal of the study was to investigate the interaction between bupivacaine and dopamine on local analgesia. After the blockade of the cutaneous trunci muscle reflex (CTMR) responses, which occurred following the drugs were subcutaneously injected in rats, the cutaneous analgesic effect of dopamine in a dosage-dependent fashion was compared to that of bupivacaine. Drug-drug interactions were evaluated by isobolographic methods. We showed the dose-dependent effects of dopamine on infiltrative cutaneous analgesia. On the 50% effective dose (ED50) basis, the rank of drug potency was bupivacaine (1.99 [1.92-2.09] μmol/kg) greater than dopamine (190 [181-203] μmol/kg) (P<0.01). At the equianalgesic doses (ED25, ED50, and ED75), dopamine elicited a similar duration of cutaneous analgesia compared with bupivacaine. The addition of dopamine to the bupivacaine solution exhibited a synergistic effect. Our pre-clinical data showed that dopamine produced a dose-dependent effect in producing cutaneous analgesia. When compared with bupivacaine, dopamine produced a lesser potency with a similar duration of cutaneous analgesia. Dopamine added to the bupivacaine preparation resulted in a synergistic analgesic effect., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Bendamustine combined with other drugs is clinically efficacious for some adult lymphoid malignancies, but to date there are no reports of the use of such combinatorial approaches in pediatric patients. We investigated the in vitro activity of bendamustine combined with other antimetabolite drugs on B cell precursor acute lymphoblastic leukemia (BCP-ALL) cell lines established from pediatric patients with refractory or relapsed ALL. We also developed a mathematically drown improved isobologram method to assess the data objectively. Three BCP-ALL cell lines; YCUB-2, YCUB-5, and YCUB-6, were simultaneously exposed to various concentrations of bendamustine and cladribine, cytarabine, fludarabine, or clofarabine. Cell growth inhibition was determined using the WST-8 assay. Combinatorial effects were estimated using our improved isobologram method with IC80 (drug concentration corresponding to 80 % of maximum inhibition). Bendamustine alone inhibited ALL cell growth with mean IC80 values of 11.30-18.90 μg/ml. Combinations of bendamustine with other drugs produced the following effects: (1) cladribine; synergistic-to-additive on all cell lines; (2) cytarabine; synergistic-to-additive on YCUB-5 and YCUB-6, and synergistic-to-antagonistic on YCUB-2; (3) fludarabine; additive-to-antagonistic on YCUB-5, and synergistic-to-antagonistic on YCUB-2 and YCUB-6; (4) clofarabine; additive-to-antagonistic on all cell lines. Flow cytometric analysis also showed the combination effects of bendamustine and cladribine. Bendamustine/cladribine or bendamustine/cytarabine may thus represent a promising combination for salvage treatment in childhood ALL.

The purpose of the study was to estimate the ability of L-tyrosine to induce cutaneous analgesia and to investigate the interaction between L-tyrosine and the local anesthetic lidocaine. After subcutaneously injecting the rats with L-tyrosine and lidocaine in a dose-dependent manner, cutaneous analgesia (by blocking the cutaneous trunci muscle reflex-CTMR) was evaluated in response to the local pinprick. The drug-drug interaction was analyzed by using an isobolographic method. We showed that both L-tyrosine and lidocaine produced dose-dependent cutaneous analgesia. On the 50% effective dose (ED50) basis, the rank of drug potency was lidocaine (5.09 [4.88-5.38] μmol)>L-tyrosine (39.1 [36.5-41.8] μmol) (P<0.05). At the equipotent doses (ED25, ED50, and ED75), the duration of cutaneous analgesia caused by L-tyrosine lasted longer than that caused by lidocaine (P<0.01). Lidocaine co-administered with L-tyrosine exhibited an additive effect on infiltrative cutaneous analgesia. Our pre-clinical study demonstrated that L-tyrosine elicits the local/cutaneous analgesia, and the interaction between L-tyrosine and lidocaine is additive. L-tyrosine has a lower potency but much greater duration of cutaneous analgesia than lidocaine. Adding L-tyrosine to lidocaine preparations showed greater duration of cutaneous analgesia compared with lidocaine alone., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Nowadays, scourge of malaria as a fatalistic disease has increased due to emergence of drug resistance and tolerance among different strains of Plasmodium falciparum. Emergence of chloroquine (CQ) resistance has worsened the calamity as CQ is still considered the most efficient, safe and cost effective drug among other antimalarials. This urged the scientists to search for other alternatives or sensitizers that may be able to augment CQ action and reverse its resistance., Method: Three β-carbolin derivatives, namely, harmalin, harmol and harmalol were tested for their anti-plasmodial and CQ resistance reversal effects against P. falciparum 3D7 and K1. SYBRE Green-1 based drug sensitivity assay and isobologram analysis were used to screen the mentioned effects respectively., Results: All of them showed moderate anti-plasmodium effect and harmalin was the most effective as compared to the others in reversing CQ resistance and tolerance., Conclusion: The mentioned phytochemicals are not ideal to be used as conventional antimalarials and only harmalin can be suggested to reverse CQ resistance in P. falciparum K1.

Background: A common practice of managing pain globally is the combination of analgesics and this is aimed at facilitating patient compliance, simplifying prescription, and improving efficacy without increasing adverse effects. Fruit extracts of Xylopia aethiopica are used traditionally in the management of pain disorders and xylopic acid (XA) present in the fruit extract have been shown to possess analgesic properties in animals. There is the likelihood of concomitant use of XA and the commonly used analgesics in traditional settings. This study, therefore, evaluated the pharmacologic interaction between XA/morphine and xylopic/diclofenac combinations., Methods: The formalin test and acetic acid writhing test were used to study the antinociceptive activity of XA, morphine, and diclofenac. The isobolographic analysis was used to study the antinociceptive interactions between XA co-administered with morphine or diclofenac., Results: Results obtained revealed that XA (10-100 mg/kg), morphine (1-10 mg/kg), and diclofenac (1-10 mg/kg) produced dose-related antinociception with different potencies in the formalin and acetic acid writhing tests. Isobolographic analysis of XA/morphine and XA/diclofenac combinations revealed potentiation of their antinociceptive effects. The degree of potentiation calculated as interaction index showed synergism for both combinations in all the nociceptive tests., Conclusion: In conclusion, the present study demonstrated synergism for the co-administration of XA with morphine or diclofenac.

Iron chelators are increasingly combined clinically but the optimal conditions for cellular iron mobilization and mechanisms of interaction are unclear. Speciation plots for iron(III) binding of paired combinations of the licensed iron chelators desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) suggest conditions under which chelators can combine as 'shuttle' and 'sink' molecules but this approach does not consider their relative access and interaction with cellular iron pools. To address this issue, a sensitive ferrozine-based detection system for intracellular iron removal from the human hepatocyte cell line (HuH-7) was developed. Antagonism, synergism or additivity with paired chelator combinations was distinguished using mathematical isobologram analysis over clinically relevant chelator concentrations. All combinations showed synergistic iron mobilization at 8 h with clinically achievable concentrations of sink and shuttle chelators. Greatest synergism was achieved by combining DFP with DFX, where about 60% of mobilized iron was attributable to synergistic interaction. These findings predict that the DFX dose required for a half-maximum effect can be reduced by 3·8-fold when only 1 μmol/l DFP is added. Mechanisms for the synergy are suggested by consideration of the iron-chelate speciation plots together with the size, charge and lipid solubilities for each chelator. Hydroxypyridinones with low lipid solubilities but otherwise similar properties to DFP were used to interrogate the mechanistic interactions of chelator pairs. These studies confirm that synergistic cellular iron mobilization requires one chelator to have the physicochemical properties to enter cells, chelate intracellular iron and subsequently donate iron to a second 'sink' chelator., (© 2015 John Wiley & Sons Ltd.)

The synthetic rodenticide, tetramethylenedisulfotetramine (TMDT), is a persistent and highly lethal GABA-gated Cl(-) channel blocker. TMDT is clandestinely produced, remains popular in mainland China, and causes numerous unintentional and deliberate poisonings worldwide. TMDT is odorless, tasteless, and easy to manufacture, features that make it a potential weapon of terrorism. There is no effective treatment. We previously characterized the effects of TMDT in C57BL/6 mice and surveyed efficacies of GABAergic and glutamatergic anticonvulsant treatments. At 0.4 mg/kg i.p., TMDT produced neurotoxic symptomatology consisting of twitches, clonic and tonic-clonic seizures, often progressing to status epilepticus and death. If administered immediately after the occurrence of the first clonic seizure, the benzodiazepine diazepam (DZP) effectively prevented all subsequent seizure symptoms, whereas the NMDA receptor antagonist dizocilpine (MK-801) primarily prevented tonic-clonic seizures. The latter agent, however, appeared to be more effective at preventing delayed death. The present study further explored these phenomena, and characterized the therapeutic actions of DZP and MK-801 as combinations. Joint treatment with both DZP and MK-801 displayed synergistic protection against tonic-clonic seizures and 24 h lethality as determined by isobolographic analysis. Clonic seizures, however, remained poorly controlled. A modification of the treatment regimen, where DZP was followed 10 min later by MK-801, yielded a reduction in both types of seizures and improved overall outcome. Simultaneous monitoring of subjects via EEG and videography confirmed effectiveness of this sequential regimen. We conclude that TMDT blockage at GABAA receptors involves early activation of NMDA receptors, which contribute to persistent ictogenic activity. Our data predict that a sequential combination treatment with DZP followed by MK-801 will be superior to either individual therapy with, or simultaneous administration of, these two agents in treating TMDT poisoning., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Purpose: Curcumin (diferuloylmethane), a phenolic compound obtained from the rhizome of the herb Curcuma longa, is known to have anti-proliferative and anti-tumor properties. In this study, we evaluated the cytotoxic effect of curcumin alone and in combination with individual drugs like carboplatin, etoposide, or vincristine in a human retinoblastoma (RB) cancer cell line., Materials and Methods: A drug-drug interaction was analyzed using the median effect/isobologram method and combination index values were used to characterize the interaction as synergistic or additive. We also performed the apoptosis and cell-cycle kinetics study with single drugs in combination with curcumin in a human RB cell lines (Y79 and Weri-Rb1)., Results: Curcumin caused concentration-dependent decrease in cell proliferation, cell kinetics, and also induced apoptosis in both the RB cell lines. When combination of curcumin with individual drugs like carboplatin or etoposide or vincristine was treated on to RB cells, both cell viability and cell cycling were reduced and increased apoptosis was noted, in comparison with single drug treatment. These effects were significant in both the cell lines, indicating the ability of curcumin to increase the sensitivity of RB cells to chemotherapy drugs., Conclusion: Our in vitro findings showed that the combination of curcumin with single drug treatment showed marked synergistic inhibitory effect against RB cell lines. These results suggest that curcumin can be used as a modulator which may have a potential therapeutic value for the treatment of RB cancer patients.

This study investigated the cytotoxicity of combined mycotoxins of ochratoxin A (OTA), zearalenone (ZEA), and/or α-zearalenol (α-ZOL). The cytotoxicity of two mycotoxin combinations (two two-toxin combinations and one three-toxin combination) on human Hep G2 cells was evaluated using a tetrazolium salt (MTT) assay and isobologram analysis. Our results demonstrated significant cytotoxic effects of the two-toxin combination and the three-toxin combination on Hep G2 cells in a time- and concentration-dependent manner. The combination indexes (CI) were 2.73-7.67 for the OTA+ZEA combination and 1.23-17.82 for the OTA+α-ZOL combination after 24 h, 48 h, and 72 h of exposure at all inhibit concentration (IC) levels (IC10-IC90), indicating an antagonism. The CIs of the ZEA+α-ZOL combination were 1.29-2.55 after 24 h and 72 h of exposure (IC10-IC90), indicating an antagonism. The CIs of the ZEA+α-ZOL combination were 0.74-1.68 after 48 h of exposure, indicating synergism (IC80-IC90), additive effects (IC50-IC70), or antagonism (IC10-IC40). For the OTA+ZEA+α-ZOL combination, the CIs were 1.41-14.65 after 24 h, 48 h, and 72 h of exposure (IC10-IC90), indicating an antagonism., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Although nisoxetine has been shown to elicit cutaneous (peripheral) anesthesia, spinal (central) anesthesia with nisoxetine was not exposed. The aim of this study was to examine spinal anesthesia of nisoxetine and its influence on the antinociceptive action of mepivacaine. We compared nisoxetine with an established local anesthetic mepivacaine for spinal anesthesia after rats were intrathecally injected with drugs. The drugs were spinally administered alone as well as in combination, and their potencies were compared via dose-response curves and isobolographic analysis. We showed that nisoxetine, as well as mepivacaine elicited spinal anesthesia in dose-dependent manners. On a 50% effective dose (ED₅₀) basis, the spinal block effect of nisoxetine in motor function, proprioception, and nociception [0.99 (0.91-1.10), 0.85 (0.76-0.95), 0.82 (0.74-0.89)] was more potent (P < 0.05) than that of mepivacaine [1.28 (1.21-1.34), 1.14 (1.07-1.22), 0.99 (0.93-1.05)], respectively. Furthermore, the nociceptive/sensory blockade (ED₅₀) was greater than the motor blockade in both nisoxetine and mepivacaine groups (P < 0.05). Saline group (vehicle) produced no spinal anesthesia. Coadministration of nisoxetine with mepivacaine displayed an additive effect. Our data reported nisoxetine produced significant anesthesia at spinal level, and additive interaction with the local anesthetic, mepivacaine. Intrathecal nisoxetine elicited more potent spinal anesthesia than mepivacaine., (© 2012 The Authors Fundamental and Clinical Pharmacology © 2012 Société Française de Pharmacologie et de Thérapeutique.)

Leishmaniasis is a neglected disease that affects poorest population mainly in developing countries, representing one of the major causes of mortality and morbidity. Therefore, efforts to find new chemotherapeutics for leishmaniasis remain a priority. Previous reports demonstrated the in vitro and in vivo antileishmanial activity of nitazoxanide, an antiprotozoan agent used in the treatment of infectious diarrhea. The present work was carried out to determine the effect of nitazoxanide in combination with current antileishmanial drugs. Mouse peritoneal macrophages were infected with Leishmania (Leishmania) infantum amastigotes in order to calculate the 50% and 90% inhibitory concentration values. Drug interactions were assessed with fixed ratio isobologram method and fractional inhibitory concentrations (FIC50 and FIC90); sum of FIC (ΣFIC50 and ΣFIC90) and overall mean ΣFIC (xΣFIC50 and xΣFIC90) were calculated for each combination. The nature of interactions was classified according to the xΣFIC50 and xΣFIC90. The combination between nitazoxanide and amphotericin B, Glucantime(®), miltefosine and sitamaquine showed xΣFIC50 values of 1.13, 0.83, 1.06 and 0.94, respectively, indicating additive interaction. Considering the in vitro activity of nitazoxanide and the obtained results, further in vivo studies may be considered to evaluate possible drug interactions in visceral leishmaniasis., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Diabetes mellitus is the most common metabolic disorder. The major cause of mortality and morbidity here is due to the complications caused by increased glucose concentrations. All the available commercial antidiabetic drugs are associated with side effects. The combination therapy could be a new and highly effective therapeutic strategy to manage hyperglycemia. Combination of commercial drugs with phytochemicals may reduce the side effects caused by these synthetic drugs. Herbal products have been thought to be inherently safe, because of their natural origin and traditional use rather than based on systemic studies. New formulation and cocrystallisation strategies need to be adopted to match the bioavailability of the drug and the phytochemical. This review describes in detail, the observed synergy and mechanism of action between phytochemicals and synthetic drugs in effectively combating. The mode of action of combination differs significantly than that of the drugs alone; hence isolating a single component may lose its importance thereby simplifying the task of pharma industries., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

Background and Purpose: Epilepsy is the most prevalent neurological disease and is characterized by recurrent seizures. Here, we investigate (i) the anticonvulsant profiles of cannabis-derived botanical drug substances (BDSs) rich in cannabidivarin (CBDV) and containing cannabidiol (CBD) in acute in vivo seizure models and (ii) the binding of CBDV BDSs and their components at cannabinoid CB1 receptors., Experimental Approach: The anticonvulsant profiles of two CBDV BDSs (50-422 mg·kg(-1) ) were evaluated in three animal models of acute seizure. Purified CBDV and CBD were also evaluated in an isobolographic study to evaluate potential pharmacological interactions. CBDV BDS effects on motor function were also investigated using static beam and grip strength assays. Binding of CBDV BDSs to cannabinoid CB1 receptors was evaluated using displacement binding assays., Key Results: CBDV BDSs exerted significant anticonvulsant effects in the pentylenetetrazole (≥100 mg·kg(-1) ) and audiogenic seizure models (≥87 mg·kg(-1) ), and suppressed pilocarpine-induced convulsions (≥100 mg·kg(-1) ). The isobolographic study revealed that the anticonvulsant effects of purified CBDV and CBD were linearly additive when co-administered. Some motor effects of CBDV BDSs were observed on static beam performance; no effects on grip strength were found. The Δ(9) -tetrahydrocannabinol and Δ(9) -tetrahydrocannabivarin content of CBDV BDS accounted for its greater affinity for CB1 cannabinoid receptors than purified CBDV., Conclusions and Implications: CBDV BDSs exerted significant anticonvulsant effects in three models of seizure that were not mediated by the CB1 cannabinoid receptor and were of comparable efficacy with purified CBDV. These findings strongly support the further clinical development of CBDV BDSs for the treatment of epilepsy., (© 2013 The British Pharmacological Society.)

The potent and efficacious anti-dysrhythmic agent amiodarone (AM) can cause potentially life-threatening lung damage (amiodarone-induced pulmonary toxicity; AIPT), which is characterized by cell death in the lungs, followed by inflammation and fibrosis. AM's major metabolite, desethylamiodarone (DEA), has a greater toxic potency than AM and it has been suggested that DEA may act synergistically with AM to cause lung toxicity. The objective of this study was to determine the type of cytotoxic interaction between AM and DEA in HPL1A human peripheral lung epithelial cells. Cytotoxicity was measured by lactate dehydrogenase release. AM and DEA caused concentration-dependent cytotoxicity in HPL1A cells. The concentration of drug causing 50% cell death (LC50) and the Hill slope factor, which represents steepness of the concentration-cell death curve, were significantly different between AM and DEA (12.4μM and 1.98; 5.07μM and 5.43, for AM and DEA, respectively) indicating that they may induce cytotoxicity through different mechanisms. A combined concentration of 7.13μM AM plus DEA, equivalent to 41% of each compound's individual LC50 value, resulted in 50% cell death. Isobolographic analysis revealed this effect to be additive, although the combined concentrations were only slightly higher than the concentrations that defined the threshold of synergy (threshold of synergy=4.21±1.98μM AM plus 1.73±1.05μM DEA; experimental data point=5.06±0.47μM AM plus 2.07±0.47μM DEA). The cytotoxic interaction between AM and DEA may be clinically relevant in the development of AIPT., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

β-Lapachone is a phytochemotherapeutic originally isolated from Lapacho tree whose extract has been used medicinally for centuries. It is well known that NAD(P)H:quinone oxidoreductase (NQO1) activity is the principal determinant of β-Lapachone cytotoxicity. As NQO1 is overexpressed in most common carcinomas, recent investigations suggest its potential application against cancer. Photodynamic therapy (PDT) is a clinically approved and rapidly developing cancer treatment. PDT involves the administration of photosensitizer (PS) followed by local illumination with visible light of specific wavelength. In the presence of oxygen molecules, the light illumination of PS can lead to a series of photochemical reactions and consequently the generation of cytotoxic reactive oxygen species (ROS). It has been reported that β-Lapachone synergistically interacts with ionizing radiation, hyperthermia and cisplatin and that the sensitivity of cells to β-Lapachone is closely related to the activity of NQO1. So, the present study aimed to investigate the feasibility of PDT to increase the anticancer effect of β-Lapachone by up-regulating NQO1 expression on breast cancer MCF-7c3 cells. NQO1 expression was evaluated by Western blot analysis at different times after PDT using ME-ALA as PS. The cytotoxicity of the photodynamic treatment and β-Lapachone alone or in combination was determined by MTT assay and the combination index (CI)-isobologram method and the dose reduction index (DRI) analysis were used to assess the effect of drug combinations. Our studies for the first time demonstrated that the expression of NQO1 is induced 24h after photodynamic treatment. The sensitivity of cancer cells to β-Lapachone treatment increased 24h after PDT and a synergistic inhibitory effect on MCF-7c3 cells was showed. Taken together, these results lead us to conclude that the synergistic interaction between β-Lapachone and PDT in killing cells was consistent with the up-regulation of NQO1. The combination of β-Lapachone and PDT is a potentially promising modality for the treatment of cancer., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

Objective: The management of diabetes with insulin and synthetic oral hypoglycemic drugs (OHDs) can produce serious side effects and in addition fails to prevent diabetes-related complications in many patients. A new diabetes management strategy is needed that is more effective and has fewer side effects., Methods: This paper analyzes the dose- and time-dependent effect of three phytochemicals: berberine, arecoline and vanillic acid, and two antidiabetic drugs: 2,4-thiazolidinedione (TZD) and metformin, on the uptake of 2-deoxyglucose (2DG) by 3T3-L1 adipocytes. The interactions of the phytochemicals with the OHDs were analyzed with isobolograms and the combination index., Results: TZD and berberine increased 2DG uptake by 3.3-fold (with respect to control) at 15 μM and 25 μM, respectively. The same concentrations of arecoline and vanillic acid increased 2DG uptake by 3.2-and 2.9-fold, respectively, when compared with the basal level. Berberine and arecoline acted synergistically with both the OHDs, whereas vanillic acid had an additive interaction with TZD and an antagonistic interaction with metformin. Arecoline significantly increased the translocation of GLUT4 via the PPAR(γ) pathway, whereas berberine and vanillic acid did this via the AMPK-dependent pathway., Conclusions: These phytochemicals significantly reduced the expression of the enzymes involved in fatty acid and cholesterol synthesis, indicating that they might help prevent the secondary complications of diabetes. The current study suggests that berberine and arecoline could allow dosage reduction of OHDs, which could also lead to a reduction in the toxicity and side effects caused by OHDs.

Background: Propofol and remifentanil are usually co-administered and have shown synergistic effect for anesthesia. However, the synergistic effect of the two drugs on hypnosis measured by bispectral index (BIS) was controversial in previous studies. The aim of this study was to identify the interaction of propofol and remifentanil on BIS and the optimal dose combinations for hypnosis under 66% N(2)O during surgery., Methods: Patients (age 55-75 and American Society of Anesthesiologists [ASA] 1-2) undergoing gastrectomy were enrolled in this study. Propofol and remifentanil were co-administered incrementally at 1 : 1 potent ratio (the P1R1 group), at 1 : 2 potent ratio (the P1R2 group), or at 2 : 1 potent ratio (the P2R1 group) using effect site target-controlled infusion and BIS was measured. 66% N(2)O was concomitantly administered to all groups. The dose-effect curves, the 90% effective dose (EC(90)) for adequate hypnosis (BIS 40), isobolograms and combination index were obtained by Calcusyn program (Biosoft) to reveal the interaction of propofol and remifentanil., Results: The P2R1 group showed synergistic action on BIS. However, the other groups needed larger amount of each drug than the doses of additive action. The EC(90) of the P2R1 group was propofol, 3.34 µg/ml and remifentanil, 2.41 ng/ml under 66% of N(2)O., Conclusions: Propofol dominant co-administration is needed for dose reduction in BIS guided hypnosis.