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  1. Cardiovascular pleiotropic actions of DPP-4 inhibitors: a step at the cutting edge in understanding their additional therapeutic potentials
    Balakumar P, Dhanaraj SA
    Cell Signal, 2013 Sep;25(9):1799-803.
    PMID: 23707531 DOI: 10.1016/j.cellsig.2013.05.009
    Dipeptidyl peptidase 4 (DPP-4) is a serine protease enzyme expressed widely in many tissues, including the cardiovascular system. The incretin hormones such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are released from the small intestine into the vasculature during a meal, and these incretins have a potential to release insulin from pancreatic beta cells of islets of Langerhans, affording a glucose-lowering action. However, both incretins are hurriedly degraded by the DPP-4. Inhibitors of DPP-4, therefore, enhance the bioavailability of GLP-1 and GIP, and thus have been approved for better glycemic management in patients afflicted with type 2 diabetes mellitus (T2DM). Five different DPP-4 inhibitors, often called as 'gliptins', namely sitagliptin, vildagliptin, saxagliptin, linagliptin and alogliptin have been approved hitherto for clinical use. These drugs are used along with diet and exercise to lower blood sugar in diabetic subjects. T2DM is intricately related with an increased risk of cardiovascular disease. Growing body of evidence suggests that gliptins, in addition to their persuasive anti-diabetic action, have a beneficial pleiotropic action on the heart and vessels. In view of the fact of cardiovascular disease susceptibility of patients afflicted with T2DM, gliptins might offer additional therapeutic benefits in treating diabetic cardiovascular complications. Exploring further the cardiovascular pleiotropic potentials of gliptins might open a panorama in impeccably employing these agents for the dual management of T2DM and T2DM-associated perilous cardiovascular complications. This review will shed lights on the newly identified beneficial pleiotropic actions of gliptins on the cardiovascular system.
  2. A step ahead of PPARγ full agonists to PPARγ partial agonists: therapeutic perspectives in the management of diabetic insulin resistance
    Chigurupati S, Dhanaraj SA, Balakumar P
    Eur J Pharmacol, 2015 May 15;755:50-7.
    PMID: 25748601 DOI: 10.1016/j.ejphar.2015.02.043
    Described since long as a member of the nuclear receptor superfamily, peroxisome proliferator-activated receptors (PPARs) regulate the gene expression of proteins involved in glucose and lipid metabolism. PPARs indeed regulate several physiologic processes, including lipid homeostasis, adipogenesis, inflammation, and wound healing. PPARs bind natural or synthetic PPAR ligands can function as cellular sensors to regulate the gene transcription. Dyslipidemia, and type 2 diabetes mellitus (T2DM) with insulin resistance are treated using agonists of PPARα and PPARγ, respectively. The PPARγ is a key regulator of insulin sensitization and glucose metabolism, and therefore is considered as an imperative pharmacological target to combat diabetic metabolic disease and insulin resistance. Of note, currently available PPARγ full agonists like rosiglitazone display serious adverse effects such as fluid retention/oedema, weight gain, and increased incidence of cardiovascular events. On the other hand, PPARγ partial agonists are being suggested to devoid or having less incidence of these undesirable events, and are under developmental stages. Current research is on the way for the development of novel PPARγ partial agonists with enhanced therapeutic efficacy and reduced adverse effects. This review sheds lights on the current status of development of PPARγ partial agonists, for the management of T2DM, having comparatively less or no adverse effects to that of PPARγ full agonists.
  3. Dapagliflozin: glucuretic action and beyond
    Balakumar P, Sundram K, Dhanaraj SA
    Pharmacol Res, 2014 Apr;82:34-9.
    PMID: 24705156 DOI: 10.1016/j.phrs.2014.03.008
    Diabetes mellitus is a greatly challenging disease of the 21 century, and the mortality rate due to this insidious disease is increasing worldwide in spite of availability of effective oral hypoglycemic agents. Satisfactory management of glycemic control in patients afflicted with type 2 diabetes mellitus (T2DM) remains a major clinical challenge. Identification of potential pharmacological target sites is therefore continuing as an integral part of the diabetic research. The sodium-glucose co-transporter type 2 (SGLT2) expressed in the renal proximal tubule plays an essential role in glucose reabsorption. Pharmacological blockade of SGLT2 prevents glucose reabsorption and subsequently induces the elimination of filtered glucose via urine, the process is known as 'glucuresis'. Dapagliflozin is a selective inhibitor of SGLT2. The US FDA approved dapagliflozin in January 2014 to improve glycemic control along with diet and exercise in adult patients afflicted with T2DM. It has a potential to decrease glycated hemoglobin and to promote weight loss. Although the mechanism of action of dapagliflozin is not directly linked with insulin or insulin sensitivity, reduction of plasma glucose by dapagliflozin via induction of glucosuria could improve muscle insulin sensitivity. Moreover, dapagliflozin could cause diuresis and subsequently fall in blood pressure. In addition to general discussion on the pharmacology of dapagliflozin, we propose in this review the possibilities of dual antidiabetic effect of dapagliflozin and its possible additional beneficial actions in hypertensive-obese-T2DM patients through its indirect blood pressure-lowering action and reduction of body calories and weight. Long-term clinical studies are however needed to clarify this contention.
  4. Fulltext Solid-state characterization studies and effect of PEG 20000 and P90G on particle size reduction and stability of complexed glimepiride nanocrystals
    Sajeev Kumar B, Saraswathi R, Dhanaraj SA
    J Young Pharm, 2013 Sep;5(3):83-9.
    PMID: 24396247 DOI: 10.1016/j.jyp.2013.08.002
    OBJECTIVE: The objective of the present study is to formulate and characterize the properties of complexed glimepiride nanocrystals (GLP) by various techniques at different stages of its development, and to study the effect of PEG 20000 and P90G on particle size reduction and stability of nanocrystals.

    METHOD: Precipitated (GLP-PEG) and complexed NCs (GLP-PEG-P90G) of glimepiride were characterized for particle size, size distribution, zeta potential and stability assessment using photon correlation spectroscopy (PCS). The crystallinity was analyzed using differential scanning calorimetry (DSC) and X-ray powder diffraction spectroscopy (XRPD). The surface morphology and chemical stability were assessed by means of scanning electron microscopy (SEM) and infrared spectroscopy (FTIR).

    RESULTS: A formulation with drug-polymer ratio of 1:1 was most ideal in developing stable NCs as it exhibited smaller particle size and high stability. A high zeta potential was observed in all NCs after complexation indicating improved stability. DSC and XRPD studies showed no change in crystallinity after complexation. SEM analysis of complexed NCs showed presence of spherical shape particles (size below 1 μm) with a lipid coat on the surface. Stability studies on optimized formulation (F1) revealed no change in particle size during 3-month period. FTIR studies prove that the chemical identity of GLP was preserved in the samples and the formulation was stable.

    CONCLUSION: Solid-state characterization studies reveal that complexed GLP NCs are promising carriers for drug delivery and they can be safely and effectively used in design of various formulations. Also, PEG 20000 and P90G are excellent polymer and lipid for particle size reduction (nanonization) and stabilization of nanocrystals.

  5. Fulltext Simple and effective HPLC method development and its validation for Clindipine in human drug free plasma
    Muralidharan S, Kumar Jr, Dhanaraj SA
    Pak J Pharm Sci, 2015 Jan;28(1):135-8.
    PMID: 25553676
    Simple and effective high performance liquid chromatographic (HPLC) method was developed for estimation of Clindipine in drug free human drug free blank plasma. The internal standard used as Nifidipine (IS). The current method was used protein precipitating extraction of Clindipine from blank plasma. Separation was achieved on reversed-phase c18 column (25cm × 4.6mm, 5μ) and the detection was monitored by UV detector at 260 nm. The optimized mobile phase was used acetonitrile: 5mM potassium dihydrogen orthophosphate (pH 4.5), in the ratio of 60:40% v/v at a flow rate of 1.0 ml/min. This linearity was achieved in this method range of 10.0-125.0 ng/ml with regression coefficient range is 0.99. The present method is suitable in terms of precise, accurate and specific during the study. The simplicity of the method allows for application in laboratories that lack sophisticated analytical instruments such as LC-MS/MS or GC-MS/MS that are complicated, costly and time consuming rather than a simple HPLC-UV method. The present method was successfully applied for pharmacokinetic studies.
  6. Fulltext Polyherbal formulation: Concept of ayurveda
    Parasuraman S, Thing GS, Dhanaraj SA
    Pharmacogn Rev, 2014 Jul;8(16):73-80.
    PMID: 25125878 DOI: 10.4103/0973-7847.134229
    Ayurveda is one of the traditional medicinal systems of Indian. The philosophy behind Ayurveda is preventing unnecessary suffering and living a long healthy life. Ayurveda involves the use of natural elements to eliminate the root cause of the disease by restoring balance, at the same time create a healthy life-style to prevent the recurrence of imbalance. Herbal medicines have existed world-wide with long recorded history and they were used in ancient Chinese, Greek, Egyptian and Indian medicine for various therapies purposes. World Health Organization estimated that 80% of the word's inhabitants still rely mainly on traditional medicines for their health care. The subcontinent of India is well-known to be one of the major biodiversity centers with about 45,000 plant species. In India, about 15,000 medicinal plants have been recorded, in which the communities used 7,000-7,500 plants for curing different diseases. In Ayurveda, single or multiple herbs (polyherbal) are used for the treatment. The Ayurvedic literature Sarangdhar Samhita' highlighted the concept of polyherbalism to achieve greater therapeutic efficacy. The active phytochemical constituents of individual plants are insufficient to achieve the desirable therapeutic effects. When combining the multiple herbs in a particular ratio, it will give a better therapeutic effect and reduce the toxicity. This review mainly focuses on important of the polyherbalism and its clinical significance.
  7. Fulltext Evaluation of sub-chronic toxic effects of petroleum ether, a laboratory solvent in Sprague-Dawley rats
    Parasuraman S, Sujithra J, Syamittra B, Yeng WY, Ping WY, Muralidharan S, et al.
    J Basic Clin Pharm, 2014 Sep;5(4):89-97.
    PMID: 25316988 DOI: 10.4103/0976-0105.141943
    BACKGROUND: In general, organic solvents are inhibiting many physiological enzymes and alter the behavioural functions, but the available scientific knowledge on laboratory solvent induced organ specific toxins are very limited. Hence, the present study was planned to determine the sub-chronic toxic effects of petroleum ether (boiling point 40-60°C), a laboratory solvent in Sprague-Dawley (SD) rats.

    MATERIALS AND METHODS: The SD rats were divided into three different groups viz., control, low exposure petroleum ether (250 mg/kg; i.p.) and high exposure petroleum ether (500 mg/kg; i.p.) administered group. The animals were exposed with petroleum ether once daily for 2 weeks. Prior to the experiment and end of the experiment animals behaviour, locomotor and memory levels were monitored. Before initiating the study animals were trained for 2 weeks for its learning process and its memory levels were evaluated. Body weight (BW) analysis, locomotor activity, anxiogenic effect (elevated plus maze) and learning and memory (Morris water navigation task) were monitored at regular intervals. On 14(th) day of the experiment, few ml of blood sample was collected from all the experimental animals for estimation of biochemical parameters. At the end of the experiment, all the animals were sacrificed, and brain, liver, heart, and kidney were collected for biochemical and histopathological analysis.

    RESULTS: In rats, petroleum ether significantly altered the behavioural functions; reduced the locomotor activity, grip strength, learning and memory process; inhibited the regular body weight growth and caused anxiogenic effects. Dose-dependent organ specific toxicity with petroleum ether treated group was observed in brain, heart, lung, liver, and kidney. Extrapyramidal effects that include piloerection and cannibalism were also observed with petroleum ether administered group. These results suggested that the petroleum ether showed a significant decrease in central nervous system (CNS) activity, and it has dose-dependent toxicity on all vital organs.

    CONCLUSION: The dose-dependent CNS and organ specific toxicity was observed with sub-chronic administration of petroleum ether in SD rats.

  8. Classical and pleiotropic actions of dipyridamole: Not enough light to illuminate the dark tunnel?
    Balakumar P, Nyo YH, Renushia R, Raaginey D, Oh AN, Varatharajan R, et al.
    Pharmacol Res, 2014 Sep;87:144-50.
    PMID: 24861566 DOI: 10.1016/j.phrs.2014.05.008
    Dipyridamole is a platelet inhibitor indicated for the secondary prevention of transient ischemic attack. It inhibits the enzyme phosphodiesterase, elevates cAMP and cGMP levels and prevents platelet aggregation. Dipyridamole inhibits the cellular uptake of adenosine into red blood cells, platelets and endothelial cells that results in increased extracellular availability of adenosine, leading to modulation of cardiovascular function. The antiplatelet action of dipyridamole might offer therapeutic benefits in secondary stroke prevention in combination with aspirin. Inflammation and oxidative stress play an important role in atherosclerosis and thrombosis development, leading to stroke progression. Studies demonstrated anti-inflammatory, anti-oxidant and anti-proliferative actions of dipyridamole. These pleiotropic potentials of dipyridamole might contribute to improved therapeutic outcomes when used with aspirin in preventing secondary stroke. Dipyridamole was documented as a coronary vasodilator 5 decades ago. The therapeutic failure of dipyridamole as a coronary vasodilator is linked with induction of 'coronary steal' phenomenon in which by dilating resistance vessels in non-ischemic zone, dipyridamole diverts the already reduced blood flow away from the area of ischemic myocardium. Dipyridamole at high-dose could cause a marked 'coronary steal' effect. Dipyridamole, however, at low-dose could have a minimal hemodynamic effect. Low-dose dipyridamole treatment has a therapeutic potential in partially preventing diabetes mellitus-induced experimental vascular endothelial and renal abnormalities by enhancing endothelial nitric oxide signals and inducing renovascular reduction of oxidative stress. In spite of plenteous research on dipyridamole's use in clinics, its precise clinical application is still obscure. This review sheds lights on pleiotropic pharmacological actions and therapeutic potentials of dipyridamole.
  9. Development and characterization of lecithin stabilized glibenclamide nanocrystals for enhanced solubility and drug delivery
    Kumar BS, Saraswathi R, Kumar KV, Jha SK, Venkates DP, Dhanaraj SA
    Drug Deliv, 2014 May;21(3):173-84.
    PMID: 24102185 DOI: 10.3109/10717544.2013.840690
    Novel LNCs (lipid nanocrystals) were developed with an aim to improve the solubility, stability and targeting efficiency of the model drug glibenclamide (GLB). PEG 20000, Tween 80 and soybean lecithin were used as polymer, surfactant and complexing agent, respectively. GLB nanocrystals (NCs) were prepared by precipitation process and complexed using hot and cold melt technique. The LNCs were evaluated by drug loading, saturation solubility (SL), optical clarity, in vitro dissolution, solid state characterization, in vivo and stability analysis. LNCs exhibited a threefold increase in SL and a higher dissolution rate than GLB. The percentage dissolution efficiency was found to decrease with increase in PEG 20000. The average particle size was in the range of 155-842 nm and zeta potential values tend to increase after complexation. X-ray powder diffractometry and differential scanning calorimetry results proved the crystallinity prevailed in the samples. Spherical shaped particles (<1000 nm) with a lipid coat on the surface were observed in scanning electron microscopy analysis. Fourier transform infrared results proved the absence of interaction between drug and polymer and stability study findings proved that LNCs were stable. In vivo study findings showed a decrease in drug concentration to pancreas in male Wistar rats. It can be concluded that LNCs are could offer enhanced solubility, dissolution rate and stability for poorly water soluble drugs. The targeting efficiency of LNCs was decreased and further membrane permeability studies ought to be carried out.
  10. Evidences of hepatoprotective and antioxidant effect of Citrullus colocynthis fruits in paracetamol induced hepatotoxicity
    Vakiloddin S, Fuloria N, Fuloria S, Dhanaraj SA, Balaji K, Karupiah S
    Pak J Pharm Sci, 2015 May;28(3):951-7.
    PMID: 26004728
    The objective of present study was to explore the hepatoprotective and antioxidant profile of Citrullus colocynthis fruits. Hepatoprotective profile of methanolic extract of Citrullus colocynthis fruits (MECCF) was investigated on rats, which were made hepatotoxic using paracetamol. The antioxidant profile of MECCF was evaluated by conducting Catalase, Super oxide Dismutase, Lipid Peroxidation and Diphenyl Picryl Hydrazyl tests. During hepatoprotective investigation, the Paracetamol treated group II showed significant increase in total bilirubin (TB), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) and alkaline phosphatase (ALP) level. The results so obtained showed that pretreatment of rats with MECCF 300mg/kg p.o. decreases the elevated TB, SGOT, SGPT and ALP serum levels. Also, MECCF inhibitory profile was found comparable with toxicant group (Paracetamol 2g/kg, p.o.). The present study concludes that MECCF fruit possess significant hepatoprotective and antioxidant activity.
  11. Fenofibrate and dipyridamole treatments in low-doses either alone or in combination blunted the development of nephropathy in diabetic rats
    Balakumar P, Varatharajan R, Nyo YH, Renushia R, Raaginey D, Oh AN, et al.
    Pharmacol Res, 2014 Dec;90:36-47.
    PMID: 25263930 DOI: 10.1016/j.phrs.2014.08.008
    Low-doses of fenofibrate and dipyridamole have pleiotropic renoprotective actions in diabetic rats. This study investigated their combined effect relative to their individual treatments and lisinopril in rats with diabetic nephropathy. Streptozotocin (55mg/kg, i.p., once)-administered diabetic rats were allowed for 10 weeks to develop nephropathy. Diabetic rats after 10 weeks developed nephropathy with discernible renal structural and functional changes as assessed in terms of increase in kidney weight to body weight ratio (KW/BW), and elevations of serum creatinine, urea and uric acid, which accompanied with elevated serum triglycerides and decreased high-density lipoproteins. Hematoxylin-eosin, periodic acid Schiff and Masson trichrome staining confirmed renal pathological changes in diabetic rats that included glomerular capsular wall distortion, mesangial cell expansion, glomerular microvascular condensation, tubular damage and degeneration and fibrosis. Low-dose fenofibrate (30mg/kg, p.o., 4 weeks) and low-dose dipyridamole (20mg/kg, p.o., 4 weeks) treatment either alone or in combination considerably reduced renal structural and functional abnormalities in diabetic rats, but without affecting the elevated glucose level. Fenofibrate, but not dipyridamole, significantly prevented the lipid alteration and importantly the uric acid elevation in diabetic rats. Lisinopril (5mg/kg, p.o., 4 weeks, reference compound), prevented the hyperglycemia, lipid alteration and development of diabetic nephropathy. Lipid alteration and uric acid elevation, besides hyperglycemia, could play key roles in the development of nephropathy. Low-doses of fenofibrate and dipyridamole treatment either alone or in combination markedly prevented the diabetes-induced nephropathy. Their combination was as effective as to their individual treatment, but not superior in preventing the development of diabetic nephropathy.
  12. Fulltext Knowledge about the availability of the pharmacist in the Nuclear Medicine Department: A questionnaire-based study among health-care professionals
    Parasuraman S, Mueen Ahmed KK, Bin Hashim TS, Muralidharan S, Kumar KJ, Ping WY, et al.
    J Basic Clin Pharm, 2014 Dec;6(1):19-23.
    PMID: 25538467 DOI: 10.4103/0976-0105.145773
    OBJECTIVE: The objective of this study was to analyze the knowledge about the availability of the pharmacist in the nuclear medicine department among health-care professionals through a prospective cohort study.

    METHODS: A total of 741 health-care professionals participated in the study by answering 10 simple questions about the role of the pharmacist in the nuclear medicine department and the availability of pharmacist in the nuclear medicine department. An online questionnaire system was used to conduct the study, and participants were invited to participate through personal communications and by promoting the study through social websites including Facebook, LinkedIn and Google (including Gmail and Google+). The study was conducted between April 2013 and March 2014 using the http://www.freeonlinesurveys.com/Webserver. Finally, the data provided by 621 participants was analyzed. Group frequency analysis was performed using Statistical Package for the Social Sciences (SPSS) version 16 (SPSS Inc. USA).

    RESULTS: The participants were from Malaysia, India, Pakistan, Sri Lanka, Bangladesh, UAE and Nepal. In total, 312 (50.2%) female health-care professionals and 309 (49.8%) male health-care professionals participated in the study. Of the 621 participants, 390 were working in hospitals, and 231 were not working in hospitals. Of the participants who were working in hospitals, 57.6% were pharmacists. The proportion of study participants who were aware of nuclear pharmacists was 55.39%. Awareness about the role of the pharmacist in nuclear medicine was poor.

    CONCLUSION: The role of the pharmacist in a nuclear medicine unit needs to be highlighted and promoted among health-care professionals and hence that the nuclear medicine team can provide better pharmaceutical care.

  13. Fulltext Effect of edaravone in diabetes mellitus-induced nephropathy in rats
    Varatharajan R, Lim LX, Tan K, Tay CS, Teoh YL, Akhtar SS, et al.
    Korean J Physiol Pharmacol, 2016 Jul;20(4):333-40.
    PMID: 27382349 DOI: 10.4196/kjpp.2016.20.4.333
    Edaravone, a synthetic-free radical scavenger, has been reported to reduce ischemia-reperfusion-induced renal injury by improving tubular cell function, and lowering serum creatinine and renal vascular resistance. The present study investigated the effect of edaravone in diabetes mellitus-induced nephropathy in rats. A single administration of streptozotocin (STZ, 55 mg/kg, i.p.) was employed to induce diabetes mellitus in rats. The STZ-administered diabetic rats were allowed for 10 weeks to develop nephropathy. Mean body weight, lipid alteration, renal functional and histopathology were analysed. Diabetic rats developed nephropathy as evidenced by a significant increase in serum creatinine and urea, and marked renal histopathological abnormalities like glomerulosclerosis and tubular cell degeneration. The kidney weight to body weight ratio was increased. Moreover, diabetic rats showed lipid alteration as evidenced by a signifi cant increase in serum triglycerides and decrease in serum high-density lipoproteins. Edaravone (10 mg/kg, i.p., last 4-weeks) treatment markedly prevented the development of nephropathy in diabetic rats by reducing serum creatinine and urea and preventing renal structural abnormalities. In addition, its treatment, without significantly altering the elevated glucose level in diabetic rats, prevented diabetes mellitus-induced lipid alteration by reducing serum triglycerides and increasing serum high-density lipoproteins. Interestingly, the renoprotective effect of edaravone was comparable to that of lisinopril (5 mg/kg, p.o, 4 weeks, standard drug). Edaravone prevented renal structural and functional abnormalities and lipid alteration associated with experimental diabetes mellitus. Edaravone has a potential to prevent nephropathy without showing an anti-diabetic action, implicating its direct renoprotection in diabetic rats.
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