Calcium channel blockers' contribution to overcoming Current drug discovery challenges in Alzheimer's disease.

INTRODUCTION: Alzheimer's disease (AD) is a progressive, irreversible, and multifactorial brain disorder that gradually and insidiously destroys individual's memory, thinking, and other cognitive abilities. AREAS COVERED: In this perspective, the authors examine the complex and multifactorial nature of Alzheimer's disease and believe that the best approach to develop new drugs is the MTDL strategy, which obviously faces several challenges. These challenges include identifying the key combination of targets and their suitability for coordinated actions, as well as developing an acceptable pharmacokinetic and toxicological profile to deliver a drug candidate. EXPERT OPINION: Since calcium plays a crucial role in the pathology of AD, a polypharmacological approach with calcium channel blockers reinforced by activities targeting other factors involved in AD is a serious option in our opinion. This is exemplified by a phase III clinical trial using a drug combination approach with Losartan, Amlodipine (a calcium channel blocker), and Atorvastatin, as well as several MTDL-based calcium channel blockade approaches with a promising in vitro and in vivo profile.

Discovery of novel multifunctional ligands targeting GABA transporters, butyrylcholinesterase, ß-secretase, and amyloid ß aggregation as potential treatment of Alzheimer's disease.

Alzheimer's disease (AD) is a global health problem in the medical sector that will increase over time. The limited treatment of AD leads to the search for a new clinical candidate. Considering the multifactorial nature of AD, a strategy targeting number of regulatory proteins involved in the development of the disease is an effective approach. Here, we present a discovery of new multi-target-directed ligands (MTDLs), purposely designed as GABA transporter (GAT) inhibitors, that successfully provide the inhibitory activity against butyrylcholinesterase (BuChE), ß-secretase (BACE1), amyloid ß aggregation and calcium channel blockade activity. The selected GAT inhibitors, 19c and 22a - N-benzylamide derivatives of 4-aminobutyric acid, displayed the most prominent multifunctional profile. Compound 19c (mGAT1 IC50 = 10 µM, mGAT4 IC50 = 12 µM and BuChE IC50 = 559 nM) possessed the highest hBACE1 and Aß40 aggregation inhibitory activity (IC50 = 1.57 µM and 99 % at 10 µM, respectively). Additionally, it showed a decrease in both the elongation and nucleation constants of the amyloid aggregation process. In contrast compound 22a represented the highest activity and a mixed-type of eqBuChE inhibition (IC50 = 173 nM) with hBACE1 (IC50 = 9.42 µM), Aß aggregation (79 % at 10 µM) and mGATs (mGAT1 IC50 = 30 µM, mGAT4 IC50 = 25 µM) inhibitory activity. Performed molecular docking studies described the mode of interactions with GATs and enzymatic targets. In ADMET in vitro studies both compounds showed acceptable metabolic stability and low neurotoxicity. Successfully, compounds 19c and 22a at the dose of 30 mg/kg possessed statistically significant antiamnesic properties in a mouse model of amnesia caused by scopolamine and assessed in the novel object recognition (NOR) task or the passive avoidance (PA) task.

Ex Vivo and In Silico Approaches of Tracheal Relaxation through Calcium Channel Blockade of 6-Aminoflavone and Its Toxicological Studies in Murine Models.

Asthma is a condition in which a person's airways become inflamed, narrowed, and produce greater amounts of mucus than normal. It can cause shortness of breath, chest pain, coughing, or wheezing. In some cases, symptoms may be exacerbated. Thus, the current study was designed to determine the mechanism of action of 6-aminoflavone (6-NH2F) in ex vivo experiments, as well as to determine its toxicity in acute and sub-chronic murine models. Tissues were pre-incubated with 6-NH2F, and concentration-response curves to carbachol-induced contraction were constructed. Therefore, tracheal rings pre-treated with glibenclamide, 2-aminopyridine, or isoproterenol were contracted with carbachol (1 µM), then 6-NH2F relaxation curves were obtained. In other sets of experiments, to explore the calcium channel role in the 6-NH2F relaxant action, tissues were contracted with KCl (80 mM), and 6-NH2F was cumulatively added to induce relaxation. On the other hand, tissues were pre-incubated with the test sample, and after that, CaCl2 concentration-response curves were developed. In this context, 6-NH2F induced significant relaxation in ex vivo assays, and the effect showed a non-competitive antagonism pattern. In addition, 6-NH2F significantly relaxed the contraction induced by KCl and CaCl2, suggesting a potential calcium channel blockade, which was corroborated by in silico molecular docking that was used to approximate the mode of interaction with the L-type Ca2+ channel, where 6-NH2F showed lower affinity energy when compared with nifedipine. Finally, toxicological studies revealed that 6-NH2F possesses pharmacological safety, since it did not produce any toxic effect in both acute and sub-acute murine models. In conclusion, 6-aminoflavone exerted significant relaxation through calcium channel blockade, and the compound seems to be safe.

Spasmolytic effect of 1,8 cineole is mediated through calcium channel blockade in the bovine ileum.

Gastrointestinal motility disorders include increased or decreased movements. Other studies have shown that herbal components, for example, essential oils can modify the increase and decrease of gastrointestinal movements of ruminants. The 1,8-cineole being obtained from the essential oil of many plants has several effects. The present study has investigated the effect of 1,8-cineole on the contractility of bovine ileum smooth muscle. The experiment was performed on the circular smooth muscle of ileum samples taken from slaughtered cows in the organ bath. Seven cumulative concentrations of 1,8-cineole from 1.00 to 1,000 µg mL-1 were added to tissue samples. The used solution was Tyrode's solution aerated with a mixture of 95.00% oxygen and 5.00% carbon dioxide, and the temperature was set at 37.00 ˚C. The effects of 1,8-cineole on baseline contractions and three induced contractions with barium chloride, potassium chloride, and carbachol were investigated. The effects of 1,8-cineole, and verapamil (standard calcium channel blocker) on calcium channels were assessed. The results revealed that 1,8-cineole significantly inhibited spontaneous contractions as well as all spasmogen-induced contractions. The 1,8-cineole exerts its myorelaxant properties by inhibiting calcium channels in smooth muscle. It seems that 1,8-cineole has a good potential for producing antispasmodics or gastrointestinal motility modulators in veterinary medicine.

Antihypertensive and vasorelaxant effect of leucodin and achillin isolated from Achillea millefolium through calcium channel blockade and NO production: In vivo, functional ex vivo and in silico studies.

ETHNOPHARMACOLOGICAL RELEVANCE: Achillea millefolium L. (Asteraceae), known as yarrow (milenrama), is a plant used in Mexican traditional medicine for the treatment of hypertension, diabetes, and related diseases. AIM: To determine the vasorelaxant and antihypertensive effect of A. millefollium and to isolate the main bioactive antihypertensive agents. MATERIALS AND METHODS: Organic (hexane, dichloromethane and methanol) and hydro-alcohol (Ethanol-H2O: 70:30) extracts obtained from flowers, leaves and stems were evaluated on isolated aorta rat rings with and without endothelium to determine their vasorelaxant effect. Hexane extract from flowers (HEAmF) was studied to evaluate its antihypertensive effect on spontaneously hypertensive rats (SHR). From HEAmF, bioactive compounds were obtained by bio-guided phytochemical separation through chromatography. RESULTS: Organic extracts showed the best vasorelaxant activity. Hexane extract from flowers was the most potent and efficient ex vivo vasorelaxant agent, showing significant decrease of systolic and diastolic blood pressure in SHR (p < 0.05). Phytochemical separation of HEAmF yielded two epimeric sesquiterpene lactones: leucodin (1) and achillin (2), the major components of the extract. Both 1 and 2 showed similar vasorelaxant action ex vivo (p < 0.05), and their effects where modified by L-NAME (10 µM, nitric oxide synthase inhibitor), by ODQ (1 µM, soluble guanylyl cyclase inhibitor), and also relaxed the contraction induced by KCl (80 mM). Finally, 1 and 2 intragastric administration (50 mg/kg) decreased systolic and diastolic blood pressure in SHR. CONCLUSIONS: Achillea millefolium showed antihypertensive and vasorelaxant effects, due mainly to leucodin and achillin (epimers). Both compounds showed antihypertensive activity by vasorelaxation putatively by endothelium-dependent NO release and cGMP increase, as well as by calcium channels blockade.

Methanol (80%) leaf extract of Otostegia integrifolia Benth (Lamiaceae) lowers blood pressure in rats through interference with calcium conductance.

BACKGROUND: Otostegia integrifolia Benth. (Lamiaceae) leaves are used to treat hypertension in Ethiopian folk medicine. However, the claim has so far not been investigated scientifically. Thus, the objective of this study was to evaluate the antihypertensive activity of 80% methanol leaf extract of O. integrifolia in animal model of hypertension and possible underlying mechanisms in isolated rat aorta. METHODS: Antihypertensive effect of various oral doses of the extract (250, 500 and 1000 mg/kg) was determined in fructose-induced hypertensive rats using the non-invasive tail-cuff method. Thoracic aortic strips of rats were isolated and suspended in organ bath, and the vasodepressor effect as well as the possible mechanism (s) of action were studied by means of isometric tension recording experiments ex vivo. Phytochemical analysis was also performed to suggest possible constituents related to the activity. RESULTS: Blood pressure was significantly lowered in a dose-dependent manner following extract administration, suggesting that the extract possesses antihypertensive activity. The extract also caused a dose-dependent relaxation of aortic strip precontracted with KCl at a concentration of 6.25-125 µg/L, with a maximum relaxation (100%) achieved at a cumulative concentration of 318.75 µg/ml. The relaxation mechanism was found to be independent of muscarinic receptors, prostanoids, histamine receptors, ATP dependent K+ channels, sarcoplasmic reticulum stored Ca2+ and the endothelium system. The extract shifted the Ca2+ concentration-response curve to the right similar to that caused by nifedipine, suggesting that vasorelaxation could possibly be mediated via calcium channel blockade. The extract was found to contain phenolic compounds (164.3 mg/g, expressed as gallic acid equivalents) and flavonoids (125.7 mg/g, expressed as quercetin equivalents). CONCLUSION: The findings revealed that the plant is endowed with antihypertensive activity, providing evidence for its traditional use. The effect maybe, at least in part, due to dilation of blood vessels through blockade of Ca+ 2 channels mediated by phenolic and flavonoid constituents.

Antihypertensive and vasorelaxant mode of action of the ethanol-soluble extract from Tagetes lucida Cav. aerial parts and its main bioactive metabolites.

ETHNOPHARMACOLOGICAL RELEVANCE: Tagetes lucida Cav. commonly known as "yauhtli" or "pericón" is used in Mexican traditional medicine for the treatment of anxiety, depressant diseases, pain, hypertension, among others. AIM: To evaluate the antihypertensive and vasorelaxant modes of action of a crude ethanolic extract from T. lucida aerial parts and to isolate the bioactive compounds. MATERIALS AND METHODS: Ethanolic extract was tested in an in vivo assay in SHR rats by intragastric administration at 10 and 100 mg/kg dosages, to measure and to compare hemodynamic parameters like diastolic and systolic blood pressure and heart rate. Also, extract (3.03-1000 µg/ml), fractions (3.03-1000 µg/ml) and pure isolated compounds (1.75-550 µM) were evaluated on isolated aortic rings contracted with noradrenaline (0.1 µM) to determine their vasorelaxant effect and extract-mode of action. RESULTS: Ethanolic extract of T. lucida lowered systolic and diastolic blood pressure on SHR rats without heart rate modification (P > 0.05). Moreover, the extract showed concentration-dependent relaxant effect in a partially endothelium-dependent manner (P < 0.05), through NO/cGMP system activation and calcium channel blockade. 6,7,8-trimethoxycoumarin (1), 6,7-dimethoxycoumarin (2), and 7-methoxycoumarin (3) from T. lucida are the main bioactive compounds of the extract and showed significant vasorelaxant activity. CONCLUSIONS: Results provide evidence and endorsed the antihypertensive properties attributed to T. lucida in traditional medicine, which is produced by vasorelaxant effect mainly through multitarget NO/cGMP system activation and calcium channel blockade. Coumarin derivatives 1, 2 and 3 are the responsible of the vasorelaxant activity.

Amlodipine Improves Vessel Function and Remodeling in the Lewis Polycystic Kidney Rat Mesenteric Artery.

BACKGROUND: Hypertension is a common comorbidity associated with chronic kidney disease (CKD). Treatment in these patients often involves L-type Ca2+ channel (LTCC) blockers. The effect of chronic LTCC-blockade treatment on resistance vasculature was investigated in a genetic hypertensive rat model of CKD, the Lewis Polycystic Kidney (LPK) rat. METHODS: Mixed-sex LPK and Lewis control rats (total n = 38) were allocated to treated (amlodipine 20 mg/kg/day p.o. from 4 to 18 weeks) and vehicle groups. Following systolic blood pressure and renal function assessment, animals were euthanized and mesenteric vasculature was collected for functional and structural assessment using pressure myography and histology. RESULTS: Amlodipine treatment reduced LPK rat blood pressure (untreated vs. treated: 185 ± 5 vs. 165 ± 9 mm Hg; P = 0.019), reduced plasma creatinine (untreated vs. treated: 197 ± 17 vs. 140 ± 16 µmol/l; P = 0.002), and improved some vascular structural parameters (internal and external diameters and wall-lumen ratios); however wall thickness was still increased in LPK relative to Lewis despite treatment (Lewis vs. LPK: 31 ± 2 vs. 41 ± 2 µm, P = 0.047). Treatment improved LPK rats' endothelium dysfunction, and nitric oxide-dependent and endothelium-derived hyperpolarization vasorelaxation components, and downregulated prostanoid contributions. LTCC blockade had no effect on biomechanical properties of compliance and intrinsic stiffness, nor artery wall composition. CONCLUSIONS: Our results indicate that blockade of LTCCs with amlodipine is effective in improving, to a certain extent, detrimental structural and functional vascular features of resistance arteries in CKD.

Tracheal relaxation through calcium channel blockade of Achillea millefolium hexanic extract and its main bioactive compounds.

ETHNOPHARMACOLOGICAL IMPORTANCE: Achillea millefolium L. (Asteraceae) is used for the treatment of respiratory diseases, diabetes, and hypertension. AIM: to explore its tracheal relaxant properties and clarify its functional mechanism of action on smooth muscle cells, which allow us to propose it as a potential anti-asthmatic drug. MATERIAL AND METHODS: organic and hydro-alcoholic extracts from A. millefolium were obtained by macerations, then their relaxing effect on ex vivo isolated rat trachea rings was determined. Most active extract (hexanic extract, EHAm) was studied to determine its functional mechanism of action using synergic, antagonist and inhibitor agents related with the contraction/relaxation process of the smooth muscle. Also, EHAm was subjected to bio-guided fractionation by open-column chromatography (on silica gel) using cyclohexane-EtOAc (80:20) in an isocratic way to isolate main bioactive compounds. RESULTS: organic and hydro-alcoholic extracts showed relaxant effect in a concentration-response dependent manner, being EHAm the most active. The functional mechanism of action indicates that EHAm induced a non-competitive antagonism to the muscarinic receptors ; in addition, the NO/cGMP pathway is involved in the relaxation process of the tracheal smooth muscle. However, the most important mechanism of action showed by EHAm was related with the calcium channel blockade influx into the smooth muscle cells. On the other hand, epimeric sesquiterpene lactones leucodin (1) and achillin (2) were isolated and purified, which are responsible for the observed smooth muscle relaxant activity of the extract. CONCLUSION: hexanic extract of A. millefollium induced a significant relaxant effect on tracheal rat rings by calcium channel blockade and NO release.

Airway smooth muscle relaxant activity of Cordia dodecandra A. DC. mainly by cAMP increase and calcium channel blockade.

ETHNOPHARMACOLOGICAL RELEVANCE: The fight against chronic respiratory diseases needs the exploration of new active compounds with properties that contribute to diminish the symptoms or resolve the disease alongside current therapy. MATERIALS AND METHODS: Eight extracts obtained from the bark and leaves of a Mayan medicinal plant used to treat asthma, Cordia dodecandra A. DC., were investigated for their relaxant effect on rat isolated tracheal rings pre-contracted with carbachol [1 µM]. The underlying functional mode of action of the most effective extract was assessed and the chromatographic fingerprints of more active extracts were analyzed. RESULTS: The dichloromethane bark extract (DECd-b) was the most effective and potent (Emax= 87.57 ±â€¯1.32 %; EC50 = 392.7 ±â€¯5.18 µg/mL). DECd-b relaxant effect was maximized in presence of isoproterenol (ß-adrenergic agonist, [10 µM]) and theophylline (phosphodiesterase unspecific inhibitor, [10 µM]). DECd-b also showed efficient relaxation of KCl [80 mM]-induced contraction and inhibition of CaCl2-induced contraction. Pre-incubation with propranolol (non-selective ß-adrenergic antagonist, [10 µM]), SQ22536 (adenylyl cyclase inhibitor; [100 µM]), ODQ (guanylyl cyclase inhibitor; [10 µM]), l-NAME (nitric oxide synthase inhibitor; [10 µM]), indomethacin (a cyclooxygenase unspecific inhibitor; [10 µM]), glibenclamide (ATP-sensitive potassium channel blocker; [10 µM]) and 2-aminopyridine (voltage-gated potassium channel blocker [100 µM]) did not modify the DECd-b relaxant-effect curve. The chromatographic analysis of DECd-b suggests the cordiaquinones presence with double conjugated bounds such as menaquinone. CONCLUSIONS: Results suggest that DECd-b induces relaxation mainly by cAMP increase and Ca2+ channel blockade. The chromatographic profiles and UV spectrum of DECd-b and HECd-l suggest the presence of molecules with structure of meroterpenoid naphthoquinones. This work report scientific evidence of C. dodecandra medicinal specie, which contributes to the pharmacological and phytochemical background of C. dodecandra providing an added value to the traditional use of this specie.

Functional mechanism of tracheal relaxation, antiasthmatic, and toxicological studies of 6-hydroxyflavone.

Previously, we described tracheal rat rings relaxation by several flavonoids, being 6-hydroxyflavone (6-HOF) the most active derivative of the series. Thus, its mechanism of action was determined in an ex vivo tracheal rat ring bioassay. The anti-asthmatic effect was assayed in in vivo OVAlbumin (OVA)-sensitized guinea pigs. Finally, the toxicological profile of 6-HOF was studied based on Organization of Economic Cooperation and Development guidelines with modifications. 6-HOF-induced relaxation appears to be related with receptor-operated calcium channel and voltage-operated calcium channel blockade as the main mechanism of action, and also through the production of relaxant second messengers NO and cGMP. Molecular docking supports that 6-HOF acts as calcium channel blocker and by activation of nitric oxide synthase. In addition, the in vivo anti-asthmatic experiments demonstrate the dose-dependent significant anti-allergic effect of 6-HOF induced by OVA, with best activity at 50 /kg. Finally, toxicological studies determined a LD50 > 2,000 mg/kg and, after 28 day of treatment with 6-HOF (50 mg/kg) by intragastric route, mice did not exhibit evidence of any significant toxicity. In conclusion, experiments showed that 6-HOF exerts significant relaxant activity through calcium channel blockade, and possibly, by NO/cGMP-system stimulation on rat trachea, which interferes with the contraction mechanism of smooth muscle cells in the airways. In addition, the flavonoid shows potential anti-asthmatic properties in an anti-allergic pathway. Furthermore, because the pharmacological and safety evidence, we propose this flavonoid as lead for the development of a novel therapeutic agent for the treatment of asthma and related respiratory diseases.

Calcium Ion Channels: Roles in Infection and Sepsis Mechanisms of Calcium Channel Blocker Benefits in Immunocompromised Patients at Risk for Infection.

Immunosuppression may occur for a number of reasons related to an individual's frailty, debility, disease or from therapeutic iatrogenic intervention or misadventure. A large percentage of morbidity and mortality in immunodeficient populations is related to an inadequate response to infectious agents with slow response to antibiotics, enhancements of antibiotic resistance in populations, and markedly increased prevalence of acute inflammatory response, septic and infection related death. Given known relationships between intracellular calcium ion concentrations and cytotoxicity and cellular death, we looked at currently available data linking blockade of calcium ion channels and potential decrease in expression of sepsis among immunosuppressed patients. Notable are relationships between calcium, calcium channel, vitamin D mechanisms associated with sepsis and demonstration of antibiotic-resistant pathogens that may utilize channels sensitive to calcium channel blocker. We note that sepsis shock syndrome represents loss of regulation of inflammatory response to infection and that vitamin D, parathyroid hormone, fibroblast growth factor, and klotho interact with sepsis defense mechanisms in which movement of calcium and phosphorus are part of the process. Given these observations we consider that further investigation of the effect of relatively inexpensive calcium channel blockade agents of infections in immunosuppressed populations might be worthwhile.

Tacripyrimidines, the first tacrine-dihydropyrimidine hybrids, as multi-target-directed ligands for Alzheimer's disease.

Notwithstanding the combination of cholinesterase (ChE) inhibition and calcium channel blockade within a multitarget therapeutic approach is envisaged as potentially beneficial to confront Alzheimer's disease (AD), this strategy has been scarcely investigated. To explore this promising line, a series of 5-amino-4-aryl-3,4,6,7,8,9-hexahydropyrimido [4,5-b]quinoline-2(1H)-thiones (tacripyrimidines) (4a-l) were designed by juxtaposition of tacrine, a ChE inhibitor (ChEI), and 3,4-dihydropyrimidin-2(1H)-thiones, as efficient calcium channel blockers (CCBs). In agreement with their design, all tacripyrimidines, except the unsubstituted parent compound and its p-methoxy derivative, acted as moderate to potent CCBs with activities generally similar or higher than the reference CCB drug nimodipine and were modest-to-good ChEIs. Most interestingly, the 3'-methoxy derivative (4e) emerged as the first well balanced ChEI/CCB agent, acting as low micromolar hChEI (3.05 µM and 3.19 µM on hAChE and hBuChE, respectively) and moderate CCB (30.4% at 1 µM) with no significant hepatotoxicity toward HepG2 cells and good predicted oral absorption and blood brain barrier permeability.

Vasorelaxant activity of Euphorbia furcillata Kunth mainly by activation of NO/cGMP pathway and calcium channel blockade / Actividad vasorrelajante de Euphorbia furcillata Kunth principalmente por activación de la vía NO/GMPc y bloqueo de canales de calcio]

The aim of current study was to determinate ex vivo and chromatographic fingerprint by HPLC of four extracts of Euphorbia furcillata K. Ethyl acetate extract of Euphorbia furcillata (EaEEf) was the most effective and potent extract (Emax=98.69±1.24%) and its effect was partially endothelium-dependent. Functional vasorelaxant mechanism of action of EaEEf was determinate, EaEEf showed efficient relaxation of KCl [80 mM]-induced contraction and norepinephrine and CaCl2 contraction curves showed diminution of maximal contraction in the presence of EAEEf and EaEEf-relaxation curve was shifted to the right in the presence of L-NAME (nitric oxide synthase inhibitor) and ODQ (guanylate cyclase inhibitor). Chromatographic fingerprints analysis suggests presence of diterpenoid such as abietane, tigliane, and ingenane skeletons. Our experiments suggest the EaEEf vasorelaxant activity could be attributed to diterpenoid molecules whose mechanism involves nitric oxide production and calcium channel blockade.

Se determinó el efecto vasorrelajante ex vivo y los perfiles cromatográficos mediante HPLC de cuatro extractos de Euphorbia furcillata K.. El extracto de acetato de etilo de E. furcillata (EaEEf) fue el más eficaz y potente en la contracción inducida por norepinefrina (Emax=98.69±1.24%) y el efecto fue parcialmente dependiente del endotelio vascular. Se determinó el mecanismo de acción vasorrelajante para EaEEf, este mostró ser eficaz sobre la contracción inducida por KCl [80 mM] y la curva de contracción en respuesta a norepinefrina y CaCl2 en presencia de EaEEf mostró disminución en la contracción máxima, mientras que la curva de relajación de EaEEf en presencia de L-NAME (inhibidor de óxido nítrico sintasa) y ODQ (inhibidor de guanilato ciclasa) se desplazó hacia la derecha. El análisis cromatográfico de EaEEf sugiere la presencia de moléculas diterpenoides como abietano, tigliano y esqueletos de ingenano. Nuestros resultados sugieren que el efecto vasorrelajante de EaEEf podría atribuirse a moléculas diterpenoides, cuyo mecanismo de acción involucra la producción de óxido nítrico y bloqueo de canales de calcio.

Calcium channel blockade and survival in recipients of successful renal transplant: an analysis of the FAVORIT trial results.

INTRODUCTION: Single-center and observational studies have suggested that calcium channel blocking agents may decrease the expression of sepsis in individual populations. In the renal transplant population, a role for calcium channel blockers in allograft protection and in prevention of sepsis has been postulated. We hypothesized that any important survival benefit or risk related to chronic use of calcium channel blocking agents should be discernable through an analysis of a large database of stable recipients of renal allografts who had enrolled in a large international trial. METHODS: A retrospective analysis of 4,110 renal transplant recipients who enrolled in the international Folic Acid for Vascular Outcome Reduction in Transplantation trial between 2002 and 2007 and were followed until 2010 was undertaken comparing cohorts (FAVORIT) of patients either taking (n=1,436) or not taking (n=2,674) calcium channel blocking medications. The endpoint was all-cause mortality (cardiovascular, noncardiovascular mortality, or unknown). Results were adjusted for country, age, race, sex, smoker, systolic blood pressure, diabetes mellitus, low-density lipoprotein, and chronic kidney disease status. RESULTS: There were no statistically significant differences in incidence rates of cardiovascular, noncardiovascular, and all-cause mortality between patients taking or not taking calcium channel blocking medications. CONCLUSION: Although physiologic reasoning and small series results suggest a benefit for calcium channel blocking agents for allograft protection and sepsis prevention in immunosuppressed patients, we find no clear survival benefit in a large international renal transplant trial.

Development of a Radiolabeled Amlodipine Analog for L-type Calcium Channel Imaging.

PURPOSE: The non-invasive imaging and quantification of L-type calcium channels (also known as dihydropyridine channels) in living tissues is of great interest in diagnosis of congestive heart failure, myocardial hypertrophy, irritable bowel syndrome etc. METHODS: Technetium-99m labeled amlodipine conjugate ([99mTc]-DTPA-AMLO) was prepared starting freshly eluted (<1 h) 99mTechnetium pertechnetate (86.5 MBq) and conjugated DTPAAMLO at pH 5 in 30 min at room temperature in high radiochemical purity (>99%, RTLC; specific activity: 55-60 GBq/mmol). The calcium channel blockade activity (CCBA) and apoptosis/necrosis assay of DTPA-amlodipine conjugate evaluations were performed for the conjugate. Log P, stability, bio-distribution and imaging studies were performed for the tracer followed by biodistribution studies as well as imaging. RESULTS: The conjugate demonstrated low toxicity on MCF-7 cells and CCBA (at µm level) compared to the amlodipine. The tracer was stable up to 4 h in final production and presence of human serum and log P (-0.49) was consistent with a water soluble complex. The tracer was excreted through kidneys and liver as expected for dihydropyridines; excluding excretory organs, calcium channel rich smooth muscle cells; including colon, intestine and lungs which demonstrated significant uptake. SPECT images supported the bio-distribution data up to 4 h. CONCLUSION: significant uptake of [99mTc]-DTPA-AMLO was obtained in calcium channel rich organs. The complex can be a candidate for further SPECT imaging for L-type calcium channels.

Does calcium channel blockade have a role in prevention of expression of sepsis in renal transplant recipients?

Many antihypertensive agents have been demonstrated to assist in preservation of kidney function, among them those that modulate calcium channels. Calcium channel blockers may also be of value in protecting hemodialysis patients from complications of sepsis. In diabetic recipients of kidney transplant allografts treated with cyclosporine, calcium channel blockade has been retrospectively linked to improved graft preservation and to fewer episodes of sepsis. This brief review outlines clinical and experimental publications on potential protection from sepsis by addition of calcium channel blockers to standard antibiotic therapy in individuals who may or may not have normal kidney function, or in the presence or absence of immunosuppression. Such mechanisms include blockade of antibiotic cytosolic extrusion in the cases of Pneumococci, Mycobacterium tuberculosis, Plasmodium falciparum malaria, or Schistosoma mansoni; blockade of the calcineurin/calmodulin pathway (in immunosuppressed patients allowing for lower dosage of cyclosporine); stabilization of calcium movement at the level of sarcoplasmic reticulum by which shock (vasopressor instability) is prevented; or of cytosolic calcium influx and cell death (in the case of allograft acute tubular necrosis). Given the high cost of development of new antibiotics, a role for generic calcium channel blockade in sepsis prevention should be pursued by additional studies to investigate potential links between blockade of calcium channels and expression of sepsis in at-risk populations.

Preparation and preclinical evaluation of 68Ga-DOTA-amlodipine for L-type calcium channel imaging.

AIM: In order to develop a possible tracer for L-type calcium channel imaging, we here report the development of a Ga-68 amlodipine derivative for possible PET imaging. MATERIALS AND METHODS: Amlodipine DOTA conjugate was synthesized, characterized and went through calcium channel blockade, toxicity, apoptosis/necrosis tests. [68Ga] DOTA AMLO was prepared at optimized conditions followed by stability tests, partition coefficient determination and biodistribution studies using tissue counting and co incidence imaging up to 2 h. RESULTS: [68Ga] DOTA AMLO was prepared at pH 4-5 in 7-10 min at 95°C in high radiochemical purity (>99%, radio thin layer chromatography; specific activity: 1.9-2.1 GBq/mmol) and was stable up to 4 h with a log P of -0.94. Calcium channel rich tissues including myocardium, and tissues with smooth muscle cells such as colon, intestine, and lungs demonstrated significant uptake. Co incidence images supported the biodistribution data up to 2 h. CONCLUSIONS: The complex can be a candidate for further positron emission tomography imaging for L type calcium channels.

A randomised controlled trial of calcium channel blockade (CCB) with Amlodipine For the treatment oF subcortical ischaEmic vasCular demenTia (AFFECT): study protocol.

BACKGROUND: Vascular dementia is the second most common cause of dementia affecting over seven million people worldwide, yet there are no licensed treatments. There is an urgent need for a clinical trial in this patient group. Subcortical ischaemic vascular dementia is the most common variant of vascular dementia. This randomised trial will investigate whether use of calcium channel blockade with amlodipine, a commonly used agent, can provide the first evidence-based pharmacological treatment for subcortical ischaemic vascular dementia. METHODS/DESIGN: This is a randomised controlled trial of calcium channel blockade with Amlodipine For the treatment oF subcortical ischaEmic vasCular demenTia (AFFECT) to test the hypothesis that treatment with amlodipine can improve outcomes for these patients in a phase IIb, multi-centre, double-blind, placebo-controlled randomised trial. The primary outcome is the change from baseline to 12 months in the Vascular Dementia Assessment Scale cognitive subscale (VADAS-cog). Secondary outcomes include cognitive function, executive function, clinical global impression of change, change in blood pressure, quantitative evaluation of lesion accrual based on magnetic resonance imaging (MRI), health-related quality of life, activities of daily living, non-cognitive dementia symptoms, care-giver burden and care-giver health-related quality of life, cost-effectiveness and institutionalisation. A total of 588 patients will be randomised in a 1:1 ratio to either amlodipine or placebo, recruited from sites across the UK and enrolled in the trial for 104 weeks. DISCUSSION: There are no treatments licensed for vascular dementia. The most common subtype is subcortical ischaemic vascular dementia (SIVD). This study is designed to investigate whether amlodipine can produce benefits compared to placebo in established SIVD. It is estimated that the numbers of people with VaD and SIVD will increase globally in the future and the results of this study should inform important treatment decisions. TRIAL REGISTRATION: Current Controlled Trials ISRCTN31208535 . Registered on 7 March 2014.

Vasorelaxant mode of action of dichloromethane-soluble extract from Agastache mexicana and its main bioactive compounds.

CONTEXT: Agastache mexicana (Kunth) Lint & Epling (Lamiaceae) is a plant used in Mexican traditional medicine for the treatment of hypertension, anxiety and so on. OBJECTIVE: To determine the vasorelaxant effect and functional mode of action of dichloromethane-soluble extract from A. mexicana (DEAm) and isolate the constituents responsible for the pharmacological activity. MATERIALS AND METHODS: Extracts were prepared from the aerial parts of A. mexicana (225.6 g) by successive maceration with hexane, dichloromethane and methanol (three times for 72 h at room temperature), respectively. DEAm (0.01-1000 µg/mL), fractions (at 174.27 µg/mL), acacetin and ursolic acid (UA) (0.5-500 µM) were evaluated to determine their vasorelaxant effect on ex vivo rat aorta ring model. In vivo UA antihypertensive action was determined on spontaneously hypertensive rats. RESULTS AND DISCUSSION: DEAm induced a significant vasorelaxant effect in concentration-dependent and endothelium-independent manners (EC50 = 174.276 ± 5.98 µg/mL) by a calcium channel blockade and potassium channel opening. Bio-guided fractionation allowed to isolate acacetin (112 mg), UA (2.830 g), acacetin/oleanolic acid (OA) (M1) (155 mg) and acacetin/OA/UA (M2) (1.382 g) mixtures, which also showed significant vasodilation. UA significantly diminished diastolic (80 mmHg) and systolic blood pressure (120 mmHg), but heart rate was not modified. CONCLUSION: DEAm produced significant vasorelaxant action by myogenic control cation. The presence of acacetin, OA and UA into the extract was substantial for the relaxant activity of DEAm. In vivo antihypertensive action of UA corroborates the use of A. mexicana as an antihypertensive agent on Mexican folk medicine.