TLR4 inhibitors through inhibiting (MYD88-TRIF) pathway, protect against experimentally-induced intestinal (I/R) injury.

Intestinal ischemia/reperfusion (I/R) injury is a serious condition that causes intestinal dysfunction and can be fatal. Previous research has shown that toll-like receptor 4 (TLR4) inhibitors have a protective effect against this injury. This study aimed to investigate the protective effects of TLR4 inhibitors, specifically cyclobenzaprine, ketotifen, amitriptyline, and naltrexone, in rats with intestinal (I/R) injury. Albino rats were divided into seven groups: vehicle control, sham-operated, I/R injury, I/R-cyclobenzaprine (10 mg/kg body weight), I/R-ketotifen (1 mg/kg body weight), I/R-amitriptyline (10 mg/kg body weight), and I/R-naltrexone (4 mg/kg body weight) groups. Anesthetized rats (urethane 1.8 g/kg) underwent 30 min of intestinal ischemia by occluding the superior mesenteric artery (SMA), followed by 2 h of reperfusion. Intestinal tissue samples were collected to measure various parameters, including malondialdehyde (MDA), nitric oxide synthase (NO), myeloperoxidase (MPO), superoxide dismutase (SOD), TLR4, intercellular adhesion molecule-1 (ICAM-1), nuclear factor kappa bp65 (NF-ĸBP65), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), macrophages CD68, myeloid differentiation factor 88 (MYD88), and toll interleukin receptor-domain-containing adaptor-inducing interferon ß (TRIF). The use of TLR4 inhibitors significantly reduced MDA, MPO, and NO levels, while increasing SOD activity. Furthermore, it significantly decreased TLR4, ICAM-1, TNF-α, MCP-1, MYD88, and TRIF levels. These drugs also showed partial restoration of normal cellular structure with reduced inflammation. Additionally, there was a decrease in NF-ĸBP65 and macrophages CD68 staining compared to rats in the I/R groups. This study focuses on how TLR4 inhibitors enhance intestinal function and protect against intestinal (I/R) injury by influencing macrophages CD86 through (MYD88-TRIF) pathway, as well as their effects on oxidation and inflammation.

Donepezil and quercetin alleviate valproate-induced testicular oxidative stress, inflammation and apoptosis: Imperative roles of AMPK/SIRT1/ PGC-1α and p38-MAPK/NF-κB/ IL-1ß signaling cascades.

The mounting evidence of valproate-induced testicular damage in clinical settings is alarming, especially for men taking valproate (VPA) for long-term or at high doses. Both donepezil (DON) and quercetin (QUE) have promising antioxidant, anti-inflammatory, and anti-apoptotic effects. Therefore, this study aimed to determine whether DON, QUE, and their combination could mitigate VPA-induced testicular toxicity and unravel the mechanisms underlying their protective effect. In this study, male albino rats were randomly categorized into six equal groups: control, VPA (500 mg/kg, I.P., for 14 days), DON (3 and 5 mg/kg), QUE (50 mg/kg), and DON 3 + QUE combination groups. The DON and QUE treatments were administered orally for 7 consecutive days before VPA administration and then concomitantly with VPA for 14 days. VPA administration disrupted testicular function by altering testicular architecture, ultrastructure, reducing sperm count, viability, and serum testosterone levels. Additionally, VPA triggered oxidative damage, inflammatory, and apoptotic processes and suppressed the AMPK/SIRT1/PGC-1α signaling cascade. Pretreatment with DON, QUE, and their combination significantly alleviated histological and ultrastructure damage caused by VPA and increased the serum testosterone level, sperm count, and viability. They also suppressed the oxidative stress by reducing testicular MDA content and elevating SOD activity. In addition, they reduced the inflammatory response by suppressing IL-1ß level, NF-κB, and the p38-MAPK expression as well as inhibiting apoptosis by diminishing caspase-3 and increasing Bcl-2 expression. These novel protective effects were mediated by upregulating AMPK/SIRT1/PGC-1α signaling cascade. In conclusion, these findings suggest that DON, QUE, and their combination possess potent protective effects against VPA-induced testicular toxicity.

The Influence of Strain Rate Behavior on Laminated Glass Interlayer Types for Cured and Uncured Polymers.

Recent explosions and impact events have highlighted the exposure of civil structures, prompting the need for resilient new constructions and retrofitting of existing ones. Laminated glass panels, particularly in glazed facades, are increasingly used to enhance blast resistance. However, the understanding of glass fragments and their interaction with the interlayer is still incomplete. This paper investigates experimentally the quasi-static and dynamic responses of cured and uncured polymers for seven different materials-two different products of polyvinyl butyral (PVB), two ethylene vinyl acetate products (EVA), one product of thermoplastic polyurethane (TPU), and two SentryGlas products (SG)-that were tested between 21 and 32 °C (69.8 and 89.6 °F), which is the recommended room temperature. In these experiments, the responses of PVB, EVA, TPU, and SG were evaluated under a quasi-static strain rate of 0.033 s-1 and compared to the results under a relatively higher strain rate of 2 s-1. Moreover, the high strain rate loading of the materials was accomplished using a drop-weight testing appliance to evaluate the engineering stress-strain response under strain rates between 20 and 50 s-1. The results demonstrated that with strain rates of 20 s-1, PVB behaved like a material with viscoelastic characteristics, but at 45 s-1 strain rates, PVB became a non-elastic material. SG, on the other hand, offered both a high stiffness and a high level of transparency, making it a very good alternative to PVB in structural applications. In contrast, after the maximum stress point, the response to the failure of the seven materials differed significantly. The tests provided ample information for evaluating alternative approaches to modeling these different materials in blast events.

Exposure to bromoxynil octanoate herbicide induces oxidative stress, inflammation, and apoptosis in testicular tissue via modulating NF-кB pathway.

Bromoxynil octanoate (BO) is a herbicide necessary for plant growth and production. However, it may cause damage to environment and humans. This study aimed to investigate the potential testicular toxicity of BO and its possible underlying mechanisms. Male Albino (Sprague Dawley) rats were administered BO in different doses (5, 10, 20, and 40 mg/kg/BW; P.O.) daily for 21 days. Testicular function was evaluated by determining count and viability of epididymal sperm, and testosterone. In addition, the following parameters were assessed; MDA, NO, and H2O2 as oxidative stress markers; SOD, CAT, GPx, GST, and GSH as antioxidant markers; NF-ĸB-P65 and IL-18 as inflammatory markers; caspase-9 and caspase-3 as apoptotic markers; gene expression of NF-ĸB-P65, TNF-α, BAX, Bcl-2, and caspase-3; and histopathological examination of epididymis and testis sections. The results showed a significant (P < 0.05) increase in MDA, NO, H2O2, IL-18, and caspase-9 content, NF-ĸB-P65, TNF-α, Bax, and Caspase-3 expression as compared to control. Furthermore, the count and viability of epididymal sperm, testosterone level, SOD, CAT, GPx, GST, and GSH content, and Bcl-2 expression showed a significant (P < 0.05) decrease as compared to control. In conclusion BO-induced testicular damage by altering oxidation, inflammation, and apoptosis.

Potential effects of carbon monoxide donor and its nanoparticles on experimentally induced gastric ulcer in rats.

The prevalence of gastric ulcers is increasing worldwide, especially those brought on by non-steroidal anti-inflammatory drugs (NSAIDS), so prevention is extremely crucial. The protective potential of carbon monoxide (CO) in several inflammatory disorders has been clarified. The goal of the current study was to investigate the gastroprotective effect of CO produced by its pharmacological donor (CORM2) and its nanoparticles (NPs) against indomethacin (INDO)-induced ulcers. Investigations on CORM2's dose-dependent effects were also conducted. For induction of gastric ulcer, 100 mg kg-1 of INDO was given orally. Before ulcer induction, CORM2 (5, 10, and 15 mg kg-1), CORM2 nanoparticles (5 mg kg-1), or ranitidine (30 mg kg-1) were given intraperitoneally for 7 days. Ulcer score, gastric acidity, gastric contents of malondialdehyde (MDA), nitric oxide (NO), heme oxygenase-1 (HO-1), and carboxyhemoglobin (COHb) blood content were estimated. Additionally, gene expression of nuclear factor erythroid 2-related factor 2 (NRF2) and immunohistochemical staining of cyclooxygenase-1 (COX-1) as well as cyclooxygenase-2 (COX-2) were analyzed. Results demonstrated a substantial dose-dependent decrease in ulcer score, pro-inflammatory indicators, and oxidative stress markers with CORM2 and its NPs. Furthermore, CORM2 and its NPs markedly increased NRF2, COX-1, and HO-1, but CORM2 NPs outperformed CORM2 in this regard. In conclusion, the CO released by CORM2 can protect against INDO-induced gastric ulcers dose dependently, and the highest used dose had no effect on COHb concentration.

Combination of metformin and hesperidin mitigates cyclophosphamide-induced hepatotoxicity. Emerging role of PPAR-γ/Nrf-2/NF-κB signaling pathway.

Cyclophosphamide (CP) is widely used as an immunosuppressive and chemotherapeutic drug. However, its therapeutic application is restricted by its adverse effects, particularly hepatotoxicity. Both metformin (MET) and hesperidin (HES) have promising antioxidant, anti-inflammatory, and anti-apoptotic effects. Therefore, the principal aim of the current study is to investigate the hepatoprotective effects of MET, HES, and their combinations on the CP-induced hepatotoxicity model. Hepatotoxicity was evoked by a single (I.P) injection of CP (200 mg/kg) on day 7. For this study, 64 albino rats were randomly categorized into eight equal groups; naïve, control vehicle, untreated CP (200 mg/kg, IP), and CP 200 groups treated with MET 200, HES 50, HES 100 or a combination of MET 200 with HES 50 and HES 100 respectively orally daily for 12 days. At the end of the study, the liver function biomarkers, oxidative stress, inflammatory parameters, histopathological and immunohistochemical analysis of PPAR-γ, Nrf-2, NF-κB, Bcl-2, and caspase3 were assessed. CP significantly increased serum ALT, AST, total bilirubin, hepatic MDA, NO content, NF-κB, and TNF-α. Otherwise, albumin, hepatic GSH content, Nrf-2, and PPAR-γ expression decreased considerably compared to the control vehicle group. The combinations of MET200 with HES50 or HES100 induced pronounced hepatoprotective, anti-oxidative, anti-inflammatory, and anti-apoptotic effects on CP-treated rats. The possible explanation of such hepatoprotective effects may be mediated via upregulation of Nrf-2, PPAR-γ, Bcl-2 expression, hepatic GSH content, and marked suppression of TNF-α and NF-κB expression. In conclusion, the current study showed that combining MET and HES revealed a remarkable hepatoprotective effect against CP-induced hepatotoxicity.

Combined carvacrol and cilostazol ameliorate ethanol-induced liver fibrosis in rats: Possible role of SIRT1/Nrf2/HO-1 pathway.

Carvacrol is a natural phenolic monoterpenoid, and cilostazol is a selective phosphodiesterase-3 inhibitor with antioxidant, anti-inflammatory and antiapoptotic effects. This experiment aimed to explore the hepatoprotective effects of carvacrol and cilostazol alone and in combination against alcoholic liver fibrosis (ALF), and the underlying mechanisms, using silymarin as a reference anti-fibrotic product. ALF was induced by oral administration of ethanol (1 ml/100 g/day) thrice per week. Silymarin (100 mg/kg), carvacrol (70 mg/kg), cilostazol (50 mg/kg), or carvacrol + cilostazol combination were administered daily and concurrently with ethanol for six weeks. Hepatic changes were evaluated by quantifying serum biomarkers of liver injury, hepatic MDA, GSH and NOx as oxidative stress markers, interleukin (IL)-10 as an anti-inflammatory cytokine, 4-hydroxyproline (4-HYP) as a collagen synthesis indicator, transforming growth factor (TGF)-ß1 as a profibrogenic cytokine, α-smooth muscle actin (α-SMA) as a marker of hepatic stellate cells (HSCs) activation, histopathological (necroinflammation and fibrosis) scores and hepatic sirtuin-1 (SIRT1), nuclear factor-erythroid 2-related factor 2 (Nrf2), and hemeoxygenase-1 (HO-1) mRNA levels. Our results showed that carvacrol, cilostazol, and their combination significantly ameliorated ethanol-induced hepatic fibrosis manifested as improving hepatic functions and histopathological features, attenuating α-SMA immunostaining, reducing TGF-ß1 and 4-HYP levels, suppressing oxidativeinjury and elevating IL-10 contents. Such effects were accompanied by upregulating SIRT1, Nrf2 and HO-1 genes. This work disclosed for the first time the hepatoprotective effect of carvacrol against ALF and, to a greater extent, with carvacrol + cilostazol combination that could be partially accredited to SIRT1/Nrf2/HO-1 pathway with consequent antioxidant, anti-inflammatory, and anti-fibrotic features.

Protective effect of cilostazol and verapamil against thioacetamide-induced hepatotoxicity in rats may involve Nrf2/GSK-3ß/NF-κB signaling pathway.

Background: Verapamil (VER) and cilostazol (Cilo) are mostly used as cardiovascular drugs; they have beneficial effects on different organs toxicities. Aim: we investigated whether the Nuclear factor erythroid 2-related factor 2 (Nrf2), Glycogen synthase kinase-3ß (GSK-3ß), and Nuclear factor-kappa B (NF-κB) pathway involved in the protective role of these drugs against Thioacetamide (TAA) induced hepatotoxicity. Method: male rats were randomized divided into five groups, each group (n = 10): control, TAA, VER+TAA, Cilo+TAA, and VER+Cilo+TAA groups. Hepatotoxicity induced in rats by TAA injection once on the 7th day of the experiment. Results: TAA-induced hepatotoxicity indicated by a significant elevated in serum markers (Alanine aminotransferases (ALT), Aspartate aminotransferases (AST), and bilirubin), oxidative stress markers (Malondialdehyde (MDA), and Nitric oxide (NO)), and protein levels markers (NF-κB, and S100 calcium-binding protein A4 (S100A4)). Also, TAA decreased Nrf2, and increased GSK-3ß genes expression. Histopathological alterations in the liver also appeared as a response to TAA injection. On the other hand VER and/or Cilo significantly prevented TAA-induced hepatotoxicity in rats through significantly decreased in ALT, AST, bilirubin, MDA, NO, NF-κB, and S100A4 protein levels. Also, they increased Nrf2 and decreased GSK-3ß genes expression which caused improvement in the histopathological changes of the liver. Conclusion: the addition of verapamil to cilostazol potentiated the hepatoprotective activity, and inhibited the progression of hepatotoxicity caused by TAA through the Nrf2/GSK-3ß/NF-κBpathway and their activity on oxidative stress, inflammation, and NF-κB protein expression.

Protective role of irbesartan against cyclophosphamide-induced testicular damage in rats via up-regulating PPAR-γ signaling and ameliorating NF-κB/NLRP3/IL-18 inflammatory axis.

BACKGROUND: Cancer and its therapies can impact fertility in various ways, and therefore a growing number of cancer survivors face fertility as a significant concern. The cytotoxic alkylating agent cyclophosphamide (CP) is commonly used as an antineoplastic agent; unfortunately, its use is significantly associated with male infertility and damage to the reproductive system. AIM: The present study aimed to assess the possible beneficial effects of Irbesartan (IRB) in a rat model of CP-induced testicular toxicity. MAIN METHODS: The effects of treatment were assessed by measuring peroxisome proliferator-activated receptor gamma (PPAR-γ) expression via qRT-PCR, the immunohistochemical (IHC) assessment of apoptotic markers, NOD-like receptor protein 3 (NLRP3), and nuclear factor-κB (NF-κB), determination of the count and viability of epididymal sperm, oxidative stress markers via biochemical analysis, serum testosterone, caspase-1, and interleukin-18 (IL-18) levels via ELISA, histopathological assessment, and fibrosis by Masson's trichrome (MT) stain. KEY FINDINGS: There was a significant increase in malondialdehyde (MDA), caspase-1, and IL-18 contents, NF-κB, NLRP3, Bcl-2-associated X protein (Bax), caspase-3, and MT staining in testicular tissue after CP administration compared to the normal control group. Whereas reduced glutathione (GSH), superoxide dismutase (SOD), PPAR-γ expression, B-cell lymphoma-2 (Bcl-2) staining, serum testosterone, and the count and viability of epididymal sperm were decreased compared to the normal control group. The IRB treatment has reversed CP-induced testicular toxicity. SIGNIFICANCE: It is possible to conclude that IRB revealed a significant testicular protective effect against CP via antioxidant, anti-apoptotic, and anti-inflammatory effects.

The ponatinib/gossypol novel combination provides enhanced anticancer activity against murine solid Ehrlich carcinoma via triggering apoptosis and inhibiting proliferation/angiogenesis.

The search for new antitumor agents or combinations that are more effective and, hopefully, provide fewer health hazards is ongoing. Therefore, this study investigated the efficacy of a novel combination of ponatinib, a multi-targeted tyrosine kinase inhibitor, and the natural phytochemical gossypol against murine solid Ehrlich carcinoma. Six groups of ten mice each received vehicle (I), ponatinib in doses of 10 and 15 mg/kg (II, III) respectively, gossypol in a dose of 4 mg/kg (IV), and ponatinib (10 or 15 mg/kg) in combination with gossypol (4 mg/kg; V, VI). All treatments started on the 12th post-Ehrlich ascites carcinoma (EAC) implantation day and were administered intraperitoneally in daily doses for 3 weeks. Treatment of EAC-bearing mice with ponatinib/gossypol combination improved anticancer efficacy over either drug alone, as demonstrated by greater decreases in tumor weight and volume, and ponatinib (10 mg/kg)/gossypol combination was more efficient than ponatinib (15 mg/kg). Mechanistically, the ponatinib/gossypol combination significantly increased apoptotic markers p53, Bax, and caspase-9 while decreasing anti-apoptotic marker Bcl-2. Furthermore, it greatly decreased proliferative and angiogenic markers, FGFR4 and VEGF, respectively. Histopathology revealed a significant decline in neoplastic cells, the majority of which have necrotic changes and numerous apoptotic bodies, as well as a decrease in mitotic figures and tumor giant cells, indicating the capacity to suppress cancer proliferation/persistence. Overall, gossypol could be used as an adjuvant medication for ponatinib in cancer treatment, possibly leading to successful dose reductions and fewer side effects; however, further research is needed before a clinical application could be feasible.

Novel in vivo potential of trifluoperazine to ameliorate doxorubicin-induced cardiotoxicity involves suppression of NF-κB and apoptosis.

AIMS: Cardiotoxicity of doxorubicin frequently complicates treatment outcome. Aberrantly activated calcium/calmodulin pathway can eventually trigger signaling cascades that mediate cardiotoxicity. Therefore, we tested the hypothesis that trifluoperazine, a strong calmodulin antagonist, may alleviate this morbidity. MATERIALS AND METHODS: Heart failure and cardiotoxicity were assessed via echocardiography, PCR, immunohistochemistry, histopathology, Masson's trichrome staining and transmission electron microscopy. Whereas liver and kidney structural and functional alterations were evaluated histopathologically and biochemically. KEY FINDINGS: Results revealed that combination treatment with trifluoperazine could overcome doxorubicin-induced heart failure with reduced ejection fraction. Moreover, heart weight/body weight ratio and histopathological examination showed that trifluoperazine mitigated doxorubicin-induced cardiac atrophy, inflammation and myofibril degeneration. Transmission electron microscopy further confirmed the marked restoration of the left ventricular ultrastructures by trifluoperazine pretreatment. In addition, Masson's trichrome staining revealed that trifluoperazine could significantly inhibit doxorubicin-induced left ventricular remodeling by fibrosis. Of note, doxorubicin induced the expression of myocardial nuclear NF-κB-p65 and caspase-3 which were markedly inhibited by trifluoperazine, suggesting that cardioprotection conferred by trifluoperazine involved, at least in part, suppression of NF-κB and apoptosis. Furthermore, biochemical and histopathological examinations showed that trifluoperazine improved doxorubicin-induced renal and hepatic impairments both functionally and structurally. SIGNIFICANCE: In conclusion, the present in vivo study is the first to provide evidences underscoring the protective effects of trifluoperazine that may pave the way for repurposing this calmodulin antagonist in ameliorating organ toxicity by doxorubicin.

Nephroprotective effects of febuxostat and/or mirtazapine against gentamicin-induced nephrotoxicity through modulation of ERK 1/2, NF-κB and MCP1.

OBJECTIVES: This study was conducted to evaluate the potential nephroprotective effects of febuxostat, mirtazapine, and their combination against gentamicin-induced nephrotoxicity. METHODS: Induction of nephrotoxicity was achieved via gentamicin injection (100 mg/kg, I.P., for 7 days). Two different doses of mirtazapine (15-30 mg/kg), febuxostat (5-10 mg/kg), and their combination were administered daily for 14 days prior to gentamicin injection and then concomitantly with gentamicin for additional 7 days. Nephrotoxicity was evaluated histopathologically and biochemically. Renal caspase-3, extracellular signal-regulated protein kinase 1/2 (ERK1/2), nuclear factor-kappa-ß (NF-κß), and monocyte chemoattractant protein (MCP-1) were assayed. RESULTS: Febuxostat and mirtazapine significantly (p < 0.05) alleviated biochemical and histopathological alterations that were induced by gentamicin and, for the first time, significantly decreased the renal levels of ERK1/2 and MCP-1. Conclusion: Febuxostat and mirtazapine were found to have a synergistic impact in reducing gentamicin-induced nephrotoxicity. EXPERT OPINION: The utility of nonpurine xanthine oxidase inhibitor, such as febuxostat and mirtazapine are offering a new potential opportunity for the future nephroprotective effects therapy: Febuxostat and mirtazapine are found to have a synergistic impact in reducing gentamicin-induced nephrotoxicity.

Enhanced in vivo targeting of estrogen receptor alpha signaling in murine mammary adenocarcinoma by nilotinib/rosuvastatin novel combination.

The development of resistance to endocrine therapy of estrogen receptor alpha (ERα)-positive breast cancer is inevitable, necessitating the introduction of alternative treatment strategies. Therefore, the current study was carried out to investigate the in vivo efficacy and tolerability of nilotinib/rosuvastatin novel combination against ERα-positive breast carcinoma. Results showed that treatment of tumor-bearing mice with nilotinib/rosuvastatin exerted a significant antitumor activity. Mechanistically, the combination treatment efficiently inhibited the in vivo ERα protein expression, whereas ERα mRNA levels were unaffected suggesting a posttranslational regulation. In addition, the combination treatment markedly downregulated the expression of two ERα downstream target genes: C3 and pS2 confirming the inhibition of ERα signaling in vivo. Further, nilotinib/rosuvastatin combination strongly induced apoptosis evidenced by a marked caspase-3 cleavage and downregulation of tumor nitric oxide levels. Moreover, histopathology showed significant declines in mitotic figures and tumor giant cells implying the in vivo capability of the combination treatment to interfere with cancer cell proliferation and persistence. Of note, the combination treatment abrogated nilotinib-induced hypercholesterolemia and did not adversely affect the liver function or body weight. Overall, the present study provided evidences that warrant further assessment of nilotinib/rosuvastatin combination as an alternative therapeutic modality for ERα-positive breast cancer.

Backpack Forces on the Spine.

OBJECT: Backpacks are standard load carriers for people of all ages, especially school children and the military. Previous studies have described the impact of the forces exerted by backpacks on load distribution, back pain, and gait. The objective of this study was to use finite element analysis (FEA) to assess the effects of incremental weights in a backpack on the spine. METHODS: To assess the forces experienced by the spine under the incremental addition of weight to a backpack, we performed a finite element simulation using commercially available 'BodyParts3D/Anatomography' data, which were imported into FEA software. We studied two different scenarios: 1) a regular backpack with incrementally placed weights using both shoulder straps with the spine in a neutral position, and 2) a regular backpack with incrementally placed weights using both shoulder straps with the spine tilted forward 20 degrees. The spine model was physiologically accurate. RESULTS: For all of the added weights examined (1-100 pounds; 0.45-45.36 kg), the force experienced by the neutral spine was 7.2-fold the added weight. For the 20 degrees-forward posture, this value rose to 11.6-fold. CONCLUSIONS: These findings should help to clarify the forces experienced by the spine due to objects in a backpack. For example, this should help spinal surgeons to better understand the tremendous importance of sagittal plane alignment in planning their surgical reconstructions.

Effect of clarithromycin and fluconazole on the pharmacokinetics of montelukast in human volunteers.

OBJECTIVE: Montelukast, a leukotriene receptor antagonist, is used in the treatment of asthma. The objective of the study reported here was to determine whether multiple doses of clarithromycin or fluconazole affect the pharmacokinetics of montelukast. METHODS: This was a four-phase cross-over study with a washout period of 2 weeks between phases. In phase 1, 12 volunteers received a single oral dose of 10 mg montelukast. In phase 2, the volunteers received a single, oral dose of 1,000 mg clarithromycin once daily for 2 days, followed by, on day 3, a single oral dose of 10 mg montelukast co-administered with clarithromycin. In phase 3, a single oral dose of 50 mg fluconazole was given once daily for 6 days, followed by, on day 7, a single oral dose of 10 mg montelukast co-administered with 50 mg fluconazole. In the last phase (phase 4), a single oral dose of 150 mg fluconazole was given once daily for 6 days, followed by, on day 7, a single oral dose of 10 mg montelukast co-administered with 150 mg fluconazole. The plasma concentration of montelukast was measured by high performance liquid chromatography for 24 h. RESULTS: Following clarithromycin co-administration, the area under the concentration-time curve from zero to infinity ( AUC(0-∞)) of montelukast increased by 144% [90% confidence interval (CI) 2.03-2.86]. The co-administration of a single oral dose of 150 and 50 mg fluconazole decreased the montelukast AUC(0-∞) by 30.7 (90% CI 0.53-0.81) and 38.8% (90% CI 0.57-0.69), respectively. CONCLUSIONS: Clarithromycin increased the plasma concentrations of montelukast whereas fluconazole reduced the plasma concentrations of montelukast. The mechanism of the interaction is probably due to interference of the interacting drugs with transporters mediating the uptake of montelukast.