Targeting cyclooxygenase-2 in depression is not a viable therapeutic approach and may even aggravate the pathophysiology underpinning depression

Depression is a complex progressive disorder accompanied by activation of inflammatory and Th-1 driven pathways, oxidative and nitrosative stress (O&NS), lowered antioxidant levels, mitochondrial dysfunctions, neuroprogression and increased bacterial translocation. In depression, activation of immuno-inflammatory pathways is associated with an increased risk for cardio-vascular disorder (CVD). Because of the inflammatory component, the use of cyclooxygenase 2 (COX-2) inhibitors, such as celecoxib, has been advocated to treat depression. Electronic databases, i.e. PUBMED, Scopus and Google Scholar were used as sources for this selective review on the effects of COX-2 inhibitors aggravating the abovementioned pathways. COX-2 inhibitors may induce neuroinflammation, exacerbate Th1 driven responses, increase lipid peroxidation, decrease the levels of key antioxidants, damage mitochondria and aggravate neuroprogression. COX-2 inhibitors may aggravate bacterial translocation and CVD through Th1-driven mechanisms. COX-2 inhibitors may aggravate the pathophysiology of depression. Since Th1 and O&NS pathways are risk factors for CVD, the use of COX-2 inhibitors may further aggravate the increased risk for CVD in depression. Selectively targeting COX-2 may not be a viable therapeutic approach to treat depression. Multi-targeting of the different pathways that play a role in depression is more likely to yield good treatment results.

Role of P-glycoprotein in limiting the brain penetration of glabridin, an active isoflavan from the root of Glycyrrhiza glabra.

Purpose. Glabridin is a major active constituent of Glycyrrhiza glabra which is commonly used in the treatment of cardiovascular and central nervous system (CNS) diseases. Recently, we have found that glabridin is a substrate of P-glycoprotein (PgP/MDR1). This study aimed to investigate the role of PgP in glabridin penetration across the blood–brain barrier (BBB) using several in vitro and in vivo models.
Materials and Methods. Cultured primary rat brain microvascular endothelial cells (RBMVECs) were used in the uptake, efflux and transcellular transport studies. A rat bilateral in situ brain perfusion model was used to investigate the brain distribution of glabridin. The brain and tissue distribution of glabridin in rats with or without coadministered verapamil or quinidine were examined with correction for the tissue residual blood. In addition, the brain distribution of glabridin in mdr1a(-/-) mice was compared with the wild-type mice. Glabridin in various biological matrices was determined by a validated liquid chromatography mass spectrometric method.
Results. The uptake and efflux of glabridin in cultured RBMVECs were ATP-dependent and significantly altered in the presence of a PgP or multi-drug resistance protein (Mrp1/2) inhibitor (e.g. verapamil or MK-571). A polarized transport of glabridin was found in RBMVEC monolayers with
facilitated efflux from the abluminal (BL) to luminal (AP) side. Addition of a PgP or Mrp1/2 inhibitor in both luminal and abluminal sides attenuated the polarized transport across RBMVECs. In a bilateral in situ brain perfusion model, the uptake of glabridin into the cerebrum increased from 0.42 T 0.09% at 1 min to 9.27 T 1.69% (ml/100 g tissue) at 30 min and was significantly greater than that for sucrose. Coperfusion of a PgP or Mrp1/2 inhibitor significantly increased the brain distribution of glabridin by 33.6j142.9%. The rat brain levels of glabridin were only about 27% of plasma levels when corrected by tissue residual blood and it was increased to up to 44% when verapamil or quinidine was coadministered. The area under the brain concentration-time curve (AUC) of glabridin in mdr1a(-/-) mice was 6.0-fold higher than the wild-type mice.
Conclusions. These findings indicate that PgP limits the brain penetration of glabridin through the BBB and PgP may cause drug resistance to glabridin (licorice) therapy for CNS diseases and potential drugglabridin interactions. However, further studies are needed to explore the role of other drug transporters (e.g. Mrp1-4) in restricting the brain penetration of glabridin.

Transport of cryptotanshinone, a major active triterpenoid in Salvia miltiorrhiza Bunge widely used in the treatment of stroke and Alzheimers disease, across the blood-brain

Cryptotanshinone (CTS), a major constituent from the roots of Salvia miltiorrhiza (Danshen), is widely used in the treatment of coronary heart disease, stroke and less commonly Alzheimer's disease. Our recent study indicates that CTS is a substrate for Pglycoprotein (PgP/MDR1/ABCB1). This study has investigated the nature of the brain distribution of CTS across the brain-blood barrier (BBB) using several in vitro and in vivo rodent models. A polarized transport of CTS was found in rat primary microvascular endothelial cell (RBMVEC) monolayers, with facilitated efflux from the abluminal side to luminal side. Addition of a PgP (e.g. verapamil and quinidine) or multi-drug resistance protein 1/2 (MRP1/2) inhibitor (e.g. probenecid and MK-571) in both luminal and abluminal sides attenuated the polarized transport. In a bilateral in situ brain perfusion model, the uptake of CTS into the cerebrum increased from 0.52 ± 0.1% at 1 min to 11.13 ± 2.36 ml/100 g tissue at 30 min and was significantly greater than that of sucrose. Co-perfusion of a PgP/MDR1 (e.g. verapamil) or MRP1/2 inhibitor (e.g. probenecid) significantly increased the brain distribution of CTS by 35.1-163.6%. The brain levels of CTS were only about 21% of those in plasma, and were significantly increased when coadministered with verapamil or probenecid in rats. The brain levels of CTS in rats subjected to middle cerebral artery occlusion and rats treated with quinolinic acid (a neurotoxin) were about 2- to 2.5-fold higher than the control rats. Moreover, the brain levels in mdr1a(-/-) and mrp1(-/-) mice were 10.9- and 1.5-fold higher than those in the wild-type mice, respectively. Taken collectively, these findings indicate that PgP and Mrp1 limit the brain penetration of CTS in rodents, suggesting a possible role of PgP and MRP1 in limiting the brain penetration of CTS in patients and causing drug resistance to Danshen therapy and interactions with conventional drugs that are substrates of PgP and MRP1. Further studies are needed to explore the role of other drug transporters in restricting the brain penetration of CTS and the clinical relevance.

Novel agents that potentially inhibit irinotecan-induced diarrhea

Irinotecan (CPT-11, 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin) has exhibited clinical activities against a broad spectrum of carcinomas by inhibiting DNA topoisomerase I (Topo I). However, severe and unpredictable dosing-limiting toxicities (mainly myelosuppression and severe diarrhea) hinder its clinical use. The latter consists of early and late-onset diarrhea, occurring within 24 hr or ≥ 24 hr after CPT-11 administration, respectively. This review highlights novel agents potentially inhibiting CPT-11-induced diarrhea, which are designed and tested under guidance of disposition pathways and potential toxicity mechanisms. Early-onset diarrhea is observed immediately after CPT-11 infusion and probably due to the inhibition of acetylcholinesterase activity, which can be eliminated by administration of atropine. Lateonset diarrhea appears to be associated with intestinal exposure to SN-38 (7-ethyl-10-hydroxycamptothecin), the major active metabolite of CPT-11, which may bind to Topo I and induce apoptosis of intestinal epithelia, leading to the disturbance in the absorptive and secretory functions of mucosa. CPT-11 and SN-38 may also stimulate the production of pro-inflammatory cytokines and prostaglandins (PGs), thus inducing the secretion of Na⁺ and Cl^-. Early treatment of severe late-onset diarrhea with oral high-dose loperamide has decreased patient morbidity. Extensive studies have been conducted to identify other potential agents to ameliorate diarrhea in preclinical and clinical models. These include intestinal alkalizing agents, oral antibiotics, enzyme inducers, P-glycoprotein (PgP) inhibitors, cyclooxygenase-2 (COX-2) inhibitors, tumor necrosis factor-agr (TNF-α) inhibitors, or blockers of biliary excretion of SN-38. Further studies are needed to identify the molecular targets associated with CPT-11 toxicity and safe and effective agents for alleviating CPT-11-induced diarrhea.

Reaching and influencing consumers in the prescription medicine market

Purpose – Celebrex became the first of a new class of drugs known as COX-2 selective non-steroidal anti-inflammatory drugs. It improves treatment for arthritis sufferers without compromising the protective lining of the stomach. The purpose of this paper is to illustrate how direct-to-consumer advertising (DTCA) of prescription medicines can be used to rebuild faith in the cyclooxygenase-2 (COX-2) product category.

Design/methodology/approach – The case is developed using published sources and no input is required from company representatives. The presentation style follows the classic comprehensive case format used in postgraduate teaching programmes.

Findings – Business executives and strategic marketing students would benefit from a discussion on how external environmental factors can suddenly impose a review of marketing strategy. The reader learns how management addresses the business dilemma using DTCA.

Research limitations/implications – A blockbuster rival drug Vioxx is withdrawn due to cardiovascular (CV) health safety concerns. A resulting dominant market situation soon becomes a business dilemma. The Federal Drug Administration calls for a “black box” warning label on Celebrex, the most serious type of warning.

Practical implications – The implications are that having a product in a class of its own is not enough. It highlights the need to communicate to different audiences, to both the medical profession and the end-user. Getting doctors to recommend the medicine and pulling the product through the channel by stimulating patient demand after a health scare are paramount.

Originality/value – This is the first pharmaceutical business case where the withdrawal of a rival product leaves the dominant competitor in a monopoly situation. Contrary to expectation, market share plummets despite the absence of competition.

Can we reduce disease burden from osteoarthritis?

♦ The comparison of disparate interventions for the prevention and management of osteoarthritis (OA) is limited by the quality and quantity of published efficacy studies and the use of disparate measures for reporting clinical trial outcomes.

♦ The “transfer to utility” technique was used to translate published trial outcomes into a health-related quality-of-life (utility) scale, creating a common metric which supported comparisons between disparate interventions.

♦ Total hip replacement (THR) and total knee replacement (TKR) surgery were the most effective treatments and also highly cost-effective, at estimated cost per quality-adjusted life-year (QALY) of $7500 for THR and $10 000 for TKR (best estimate).

♦ Other apparently highly cost-effective interventions were exercise and strength training for knee OA (< $5000/QALY), knee bracing, and use of capsaicin or glucosamine sulfate (< $10 000/QALY).

♦ The cost per QALY estimates of non-specific and COX-2 inhibitor non-steroidal anti-inflammatory drugs were affected by treatment-related deaths and highly sensitive to the discounting of life-years lost.

♦ OA interventions that have been shown to be ineffective (eg, arthroscopy) are targets for redistribution of healthcare resources.

♦ OA interventions which lack efficacy studies (eg, prevention programs) require further research to assist priority setting.

♦ The application of the Health-sector Wide model to OA demonstrates its role as an evidence-based model that can be successfully applied to identify marginal interventions — those to be expanded and contracted to reduce the expected burden of disease, within current healthcare resources.

Matrix Metalloproteinase-9 reduces islet amyloid formation by degrading islet amyloid polypeptide

Deposition of islet amyloid polypeptide (IAPP) as amyloid is a pathological hallmark of the islet in type 2 diabetes, which is toxic to β-cells. We previously showed that the enzyme neprilysin reduces islet amyloid deposition and thereby reduces β-cell apoptosis, by inhibiting fibril formation. Two other enzymes, matrix metalloproteinase (MMP)-2 and MMP-9, are extracellular gelatinases capable of degrading another amyloidogenic peptide, Aβ, the constituent of amyloid deposits in Alzheimer disease. We therefore investigated whether MMP-2 and MMP-9 play a role in reducing islet amyloid deposition. MMP-2 and MMP-9 mRNA were present in mouse islets but only MMP-9 activity was detectable. In an islet culture model where human IAPP (hIAPP) transgenic mouse islets develop amyloid but nontransgenic islets do not, a broad spectrum MMP inhibitor (GM6001) and an MMP-2/9 inhibitor increased amyloid formation and the resultant β-cell apoptosis. In contrast, a specific MMP-2 inhibitor had no effect on either amyloid deposition or β-cell apoptosis. Mass spectrometry demonstrated that MMP-9 degraded amyloidogenic hIAPP but not nonamyloidogenic mouse IAPP. Thus, MMP-9 constitutes an endogenous islet protease that limits islet amyloid deposition and its toxic effects via degradation of hIAPP. Because islet MMP-9 mRNA levels are decreased in type 2 diabetic subjects, islet MMP-9 activity may also be decreased in human type 2 diabetes, thereby contributing to increased islet amyloid deposition and β-cell loss. Approaches to increase islet MMP-9 activity could reduce or prevent amyloid deposition and its toxic effects in type 2 diabetes.

Bone-derived soluble factors and laminin-511 cooperate to promote migration, invasion and survival of bone-metastatic breast tumor cells

Tumor intrinsic and extrinsic factors are thought to contribute to bone metastasis but little is known about how they cooperate to promote breast cancer spread to bone. We used the bone-metastatic 4T1BM2 mammary carcinoma model to investigate the cooperative interactions between tumor LM-511 and bone-derived soluble factors in vitro. We show that bone conditioned medium cooperates with LM-511 to enhance 4T1BM2 cell migration and invasion and is sufficient alone to promote survival in the absence of serum. These responses were associated with increased secretion of MMP-9 and activation of ERK and AKT signaling pathways and were partially blocked by pharmacological inhibitors of MMP-9, AKT-1/2 or MEK. Importantly, pre-treatment of 4T1BM2 cells with an AKT-1/2 inhibitor significantly reduced experimental metastasis to bone in vivo. Promotion of survival and invasive responses by bone-derived soluble factors and tumor-derived LM-511 are likely to contribute to the metastatic spread of breast tumors to bone.

Oxidant/antioxidant imbalance is an inherent feature of depression

BACKGROUND: 50% to 60% of the people who have recovered from the first episode of depression experience a relapse. The immune system of the people suffering from depression is in a permanent state of pathological pro-inflammatory readiness. There are some reports that depressive episodes cause sensitization of immune-inflammatory pathways and that staing of depression (e.g. number of depressive episodes) is correlated with immune-inflammatory markers. The main objective of the study was to delineate whether recurrent major depression (rDD) is characterized by alterations in selected immune-inflammatory biomarkers as compared with first episode of depression (ED-I), i.e. expression of mRNA and enzymatic activity of manganese superoxide dismutase (MnSOD, SOD-2), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS, NOS-2), and cyclooxygenase-2 (COX-2). METHODS: The study was carried out in a group of 131 patients: ED-I group - 42 patients, rDD group - 89 patients. Depression severity was assessed with the 17-item Hamilton Depression Rating Scale (HDRS). The number of depression episodes and the disease duration periods were recorded in each patient. For the patients, HDRS was administered at admission during the symptomatic phase, which would generally be either before or shortly after modification of the previous antidepressant drug regimen. Reassessment of the mental condition was conducted after 8 weeks of the pharmacological treatment also with the use of the HDRS scale. RESULTS: No significant statistical differences were found between the analysed groups as regards the intensity of depressive disorders. No differences in the expression of MnSOD, MPO, COX-2 and i-NOS genes on the level of both mRNA and protein were observed between both groups. No significant interrelation was noticed between the number of depression episodes experienced and the expression of selected genes on the mRNA level and protein level. CONCLUSIONS: There is no significant difference in MnSOD, MPO, COX-2 and i-NOS between patients with recurrent depressive disorders and those in a first episode of depression. These findings suggest that these enzymes are trait markers of depression and are not related to staging of depression.

Using clinical trial data and linked administrative health data to reduce the risk of adverse events associated with the uptake of newly released drugs by older Australians: a model process

BACKGROUND: The study was undertaken to evaluate the contribution of a process which uses clinical trial data plus linked de-identified administrative health data to forecast potential risk of adverse events associated with the use of newly released drugs by older Australian patients. METHODS: The study uses publicly available data from the clinical trials of a newly released drug to ascertain which patient age groups, gender, comorbidities and co-medications were excluded in the trials. It then uses linked de-identified hospital morbidity and medications dispensing data to investigate the comorbidities and co-medications of patients who suffer from the target morbidity of the new drug and who are the likely target population for the drug. The clinical trial information and the linked morbidity and medication data are compared to assess which patient groups could potentially be at risk of an adverse event associated with use of the new drug. RESULTS: Applying the model in a retrospective real-world scenario identified that the majority of the sample group of Australian patients aged 65 years and over with the target morbidity of the newly released COX-2-selective NSAID rofecoxib also suffered from a major morbidity excluded in the trials of that drug, indicating a substantial potential risk of adverse events amongst those patients. This risk was borne out in post-release morbidity and mortality associated with use of that drug. CONCLUSIONS: Clinical trial data and linked administrative health data can together support a prospective assessment of patient groups who could be at risk of an adverse event if they are prescribed a newly released drug in the context of their age, gender, comorbidities and/or co-medications. Communication of this independent risk information to prescribers has the potential to reduce adverse events in the period after the release of the new drug, which is when the risk is greatest.Note: The terms 'adverse drug reaction' and 'adverse drug event' have come to be used interchangeably in the current literature. For consistency, the authors have chosen to use the wider term 'adverse drug event' (ADE).

Eicosapentaenoic acid, arachidonic acid and eicosanoid metabolism in juvenile barramundi Lates calcarifer

A two part experiment was conducted to assess the response of barramundi (Lates calcarifer; initial weight = 10.3 ± 0.03 g; mean ± S.D.) fed one of five diets with varying eicosapentaenoic acid (diets 1, 5, 10, 15 and 20 g/kg) or one of four diets with varying arachidonic acid (1, 6, 12, 18 g/kg) against a fish oil control diet. After 6 weeks of feeding, the addition of EPA or ARA did not impact on growth performance or feed utilisation. Analysis of the whole body fatty acids showed that these reflected those of the diets. The ARA retention demonstrated an inversely related curvilinear response to either EPA or ARA. The calculated marginal utilisation efficiencies of EPA and ARA were high (62.1 and 91.9 % respectively) and a dietary ARA requirement was defined (0.012 g/kg(0.796)/day). The partial cDNA sequences of genes regulating eicosanoid biosynthesis were identified in barramundi tissues, namely cyclooxygenase 1 (Lc COX1a, Lc COX1b), cyclooxygenase 2 (Lc COX2) and lipoxygenase (Lc ALOX-5). Both Lc COX2 and Lc ALOX-5 expression in the liver tissue were elevated in response to increasing dietary ARA, meanwhile expression levels of Lc COX2 and the mitochondrial fatty acid oxidation gene carnitine palmitoyltransferase 1 (Lc CPT1a) were elevated in the kidney. A low level of EPA increased the expression of Lc COX1b in the liver. Consideration should be given to the EPA to ARA balance for juvenile barramundi in light of nutritionally inducible nature of the cyclooxygenase and lipoxygenase enzymes.

An update on the clinical pharmacology of the dipeptidyl peptidase 4 inhibitor alogliptin used for the treatment of type 2 diabetes mellitus.

Alogliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor that is a class of relatively new oral hypoglycaemic drugs used in patients with type 2 diabetes (T2DM), can be used as monotherapy or in combination with other anti-diabetic agents, including metformin, pioglitazone, sulfonylureas and insulin with a considerable therapeutic effect. Alogliptin exhibits favorable pharmacokinetic and pharmacodynamic profiles in humans. Alogliptin is mainly metabolized by cytochrome P450 (CYP2D6) and CYP3A4. Dose reduction is recommended for patients with moderate or worse renal impairment. Side effects of alogliptin include nasopharyngitis, upper-respiratory tract infections and headache. Hypoglycaemia is seen in about 1.5% of the T2DM patients. Rare but severe adverse reactions such as acute pancreatitis, serious hypersensitivity including anaphylaxis, angioedema and severe cutaneous reactions such as Stevens-Johnson syndrome have been reported from post-marketing monitoring. Pharmacokinetic interactions have not been observed between alogliptin and other drugs including glyburide, metformin, pioglitazone, insulin and warfarin. The present review aimed to update the clinical information on pharmacodynamics, pharmacokinetics, adverse effects and drug interactions, and to discuss the future directions of alogliptin.

A mechanistic study on reduced toxicity of irontecan by coadministered thalidomide, a tumor necrosis factor-a inhibitor

Dose-limiting diarrhea and myelosuppression compromise the success of irinotecan (7-ethyl-10-[4-[1-piperidino]-1-piperidino] carbonyloxycamptothecin) (CPT-11)-based chemotherapy. A recent pilot study indicates that thalidomide attenuates the toxicity of CPT-11 in cancer patients. This study aimed to investigate whether coadministered thalidomide modulated the toxicities of CPT-11 and the underlying mechanisms using several in vivo and in vitro models. Diarrhea, intestinal lesions, cytokine expression, and intestinal epithelial apoptosis were
monitored. Coadministered thalidomide (100 mg/kg i.p. for 8 days) significantly attenuated body weight loss, myelosuppression, diarrhea, and intestinal histological lesions caused by CPT-11 (60 mg/kg i.v. for 4 days). This was accompanied by inhibition of tumor necrosis factor-, interleukins 1 and 6 and interferon-, and intestinal epithelial apoptosis. Coadministered
thalidomide also significantly increased the systemic exposure of CPT-11 but decreased that of SN-38 (7-ethyl-10-hydroxycampothecin). It significantly reduced the biliary excretion and cecal exposure of CPT-11, SN-38, and SN-38 glucuronide. Thalidomide hydrolytic products inhibited hydrolysis of CPT-11 in rat liver microsomes but not in primary rat hepatocytes. In addition, thalidomide and its major hydrolytic products, such as phthaloyl glutamic acid (PGA), increased the intracellular accumulation of CPT-11 and SN-38 in primary rat hepatocytes. They also significantly decreased the transport of CPT-11 and SN-38 in Caco-2 and parental MDCKII cells. Thalidomide and PGA also significantly inhibited P-glycoprotein (PgP/MDR1), multidrug resistance-associated protein (MRP1)- and MRP2-mediated CPT-11 and SN-38 transport in MDCKII cells. These results provide insights into the pharmacodynamic and  pharmacokinetic mechanisms for the protective effects of thalidomide against CPT-11-induced intestinal toxicity.