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Sub-chronic Effect Of Co-administration Of Methformine And Amilodipine On Some Haematological Indices In Experimental Animal
[A CASE STUDY OF WISTAR RATS]
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2.6 Efficacy of Metformin
Metformin associated serum Vitamin B12 deficiency has been evaluated thoroughly and the association between the two is well documented, however the mechanisms of interaction and potential clinical outcomes of such are still in dispute. Evidence has been given to support the theory that the metformin interaction is isolated to calcium channel interactions and an impairment of calcium-dependent membrane activity in the ileum (Bauman et al., 2000). Calcium-dependent channels allow the GIF bound Vitamin B12 to be taken up for further processing; the suggestion that metformin inhibits the action of these channels would create a barrier for the GIF bound B12 and thus lead to malabsorption. However the study showed that while malabsorption decreased after calcium supplementation, there was no corresponding increase in serum Vitamin B12 level.
The effect of calcium was not trialled independent of metformin and therefore may have an increasing effect on B12 absorption as opposed to a correcting of a metformin induced interaction. Even though the use of calcium would reverse the malabsorption it does not increase serum levels and is also potentially causes an increase in cardio vascular risk and therefore is not favoured, especially in patients with an already elevated risk level. In a contrasting perspective, Obeid et al. (2013) suggest that while patients with type 2 diabetes may show a normal extracellular Vitamin B12 level, the intracellular markers used to measure the biochemical reactions in which Cbl takes place were abnormal compared with a control population (Obeid et al., 2013). It is further suggested that the use of metformin in type 2 diabetes does not lead to malabsorption of the vitamin, but rather “cures†Vitamin B12 resistance which leads to the lowered intracellular concentrations of metabolites which indicates a lower biochemical usage of the vitamin. With this influx of Vitamin B12 into the cell the extracellular measurements (serum etc.) are seen to drop.
This suggested that there is no lack or inhibition on the metabolic pathways that Cbl is required for. The evidence provided for these claims was based on the red blood cell extracts and related metabolites of Cbl action (MMA, SAM/SAH ratio). It was observed that the metabolic markers for Vitamin B12 were lower in a population with diabetes (not on metformin) compared to a control population. The extra cellular markers were seen to be comparable or higher in the diabetic population. The population of patients with diabetes and taking metformin was seen to have a lower extracellular measurement (holotranscobalamin, serum Vitamin B12) but individuals seemed to have an improved cell content and metabolic profile of Vitamin B12 (lower MMA, better methylation index) (Obeid et al., 2013). It is through this process of thought that the study suggests that Vitamin B12 congestion in blood is associated with intracellular deficiency, highlighted by elevated total homocysteine, leading to further evidence for the theory that there is cellular Vitamin B12 resistance in patients with type 2 diabetes. While there is currently no evidence for the claim that metformin uncovers the Vitamin B12 status in patients with type 2 diabetes, it is suggested that mechanisms such as changes to cellular membrane composition or alterations to the dynamics of glycosylation processes may hold the answer. The study concludes by claiming that metformin treatment is related not only to low serum Vitamin B12 but also to improvements in the intracellular Vitamin B12 content and markers for metabolism.
An in vivo animal trial carried out by (Greibe et al., 2013). aimed to explore the potential for alternate absorption patterns for vitamin B12 caused by metformin exposure (Greibe et al.,
2013).This study incorporated the use of a study population of 18 Sprague Dawley rats. The rats were injected subcutaneously with either metformin or a saline control for 3 weeks. Following this exposure period the amount of Vitamin B12 was located and regionalized using radio-labeled B12. The results from the study reinforce what studies (Obeid et al., 2013). before have shown, that metformin treatment reduces serum Vitamin B12. It was found that a 22% reduction in Vitamin B12 levels was seen in rats exposed to metformin therapy for just 3 weeks. However the mechanism of reduction of serum levels is not investigated thoroughly. This lowering of Vitamin B12 in the blood was thought to be attributed to an increase of Vitamin B12 in the livers of treated rats which showed a 36% increase in vitamin content compared to control rats. It is suggested that this result may be consistent in humans with diabetes and taking metformin, where the serum level of Vitamin B12 is decreased due to an increased absorption proficiency and displacement of Vitamin B12 to the liver.
Furthermore the study shows that the total amount of absorbed Vitamin B12 in both rat populations (metformin vs. control) were comparable, further suggesting that there is no absence of absorption due to metformin but rather a redistribution of the vitamin. Kidneys in rats treated with metformin contained 36% less B12 than the control population, this was again attributed to increase in liver absorption. While this study brings to light some very interesting ideas and hypotheses regarding the mechanism of metformin and Vitamin B12 interaction, it has several very crucial limitations that need to be considered. While the use of animal subjects in such a trial is obviously a practical issue, the translation of such findings into human individuals may not mimic such observations as the pathogenesis of diabetes may be highly variable between species.
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ABSRACT - [ Total Page(s): 1 ]ABSTRACTMetformin, which belongs to the biguanide class, is one of the most generally used oral hypoglycemic agents. It has been used for more than 50 years and was approved by the US Food and Drug Administration (FDA) in 1994 (American Diabetes Association, 2009) whereas Amlodipine is a long acting dihydropyridine calcium channel blocker, which is used in the treatment of angina to lower the BP (Blood pressure). the aim is to know the effect of co-administration of this two drugs in Wistar rats ... Continue reading---
APPENDIX A - [ Total Page(s): 1 ]APPENDIXAPPENDIX 1: MATERIAL USED1% Ammonium oxalate10% Formalin salineAbsorbent paperAutomatic pipetteBrilliant cresyl blueCounting chamber Cyanmethaemoglobin standardDrabkin’s ReagentEDTA sample containerHematoxylin and Eosin stainKhan tubes/rackLeisfhmann stainLight microscopeMicrohaematocrit centrifugeNormal salinePasteur pipettePipette tipsRotary microtomeSpectrophotometerTimer Turk’s solution Universal sample bottle ... Continue reading---
APPENDIX B - [ Total Page(s): 1 ]APPENDIX IITable 1: haematological parameters in control, Metformine treated and Amilodipine treated Rats (Values are expressed as mean ± Standard error of means) Group A(1): control (untreated), Group B(2): co-administration of Metformin 0.00264/ml/132g and Amlodipine 0.000849/ml/132g at a single dose for 30 daysPARAMETERS GROUP A GROUP BPacked cell volume (%) 44.16±2.83 38.47±3.53Red blood cell count (x1012/L) 7 ... Continue reading---
LIST OF TABLES - [ Total Page(s): 1 ]LIST OF TABLESTable 1: Haematological parameters in control, Co-administration of Metformin and Amlodipine treated ... Continue reading---
LIST OF FIGURES - [ Total Page(s): 1 ]LIST OF FIGURESFigure 1: Shows mechanism of action of metformin Figure 2: Shows Pie chat representation of Packed cell volume of control, Co-administration of metformin and amlodipine treated Wistar Rats Figure 3: Shows Histogram representation of Hemoglobin and red blood cell count of control, Co-administration of metformin and amlodipine treated Wistar Rats Figure 4: Shows Histogram representation of red cell indicies of control, Co-administration of metformin and amlodipine t ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTTitle page Declaration Certification Dedication Acknowledgement Table of content List of table List of figures Abstract CHAPTER ONE1.0 Introduction 1.1 Background of study 1.2 Statement of Problems 1.3 Justifications 1.4 Aims 1.5 Research Objectives 1.6 Research Hypothesis 1.7 Significance of research CHAPTER TWO2.0 Literature review 2.1 Metformin 2.1.1 ... Continue reading---
CHAPTER ONE - [ Total Page(s): 2 ]CHAPTER ONE1.0 INTRODUCTION1.1 Background of the studyMetformin, which belongs to the biguanide class, is one of the most generally used oral hypoglycemic agents. It has been used for more than 50 years and was approved by the US Food and Drug Administration (FDA) in 1994 (American Diabetes Association, 2009). Currently, many clinical practice guidelines for patients with type 2 diabetes, including the American Diabetes Association (ADA), the European Association for the Study of Diabetes ... Continue reading---
CHAPTER THREE - [ Total Page(s): 4 ]From the above table,Km of rats= 6 Km of human= 37For Amlodipine, Human dose= 10mg/70kg 1kg=10/70 =0.14mg/kgAED of Amilodipine= 0.14×(6/37) =0.02mg/kgAverage weight of experimental Animal is 132g(0.132kg)If 0.02mg of Amlodipine is administered per kg.bw,(0.02×0.132)mg of Amlodipine was administered to ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 6 ]CHAPTER FOUR4.0 Results4.1 Hematological parameter in control and test groups As summarized in table 1, the mean RBC counts were 7.62 ± 2.83 x1012/L for the control and 6.53 ± 0.57 x1012/L for co-administration of metformin and amlodipine fed groups respectively. Although, decrease in RBC counts was observed in the treated (co-administration of metformin and amlodipine) dose group, these were statistically significant compared to control groups (student t test P0.05) higher in the tr ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 2 ]CHAPTER FIVE5.0 DiscussionMetformin (1,1-dimethylbiguanide) is the most widely used drug to treat type 2 diabetes, and is one of only two oral anti-diabetic drugs on the World Health Organization (WHO) list of essential medicines (American Diabetes Association, 2009). Amlodipine is a long acting dihydropyridine calcium channel blocker, which is used in the treatment of angina to lower the BP. Co-administration of Metformin and Amlodipine have been discovered to lead to vitamin B12 deficiency. Al ... Continue reading---
REFRENCES - [ Total Page(s): 4 ]Senol, M.G., Sonmez, G., Ozdag, F. and Saracoglu, M. (2008). Reversible myelopathy with vitamin B12 deficiency. Singapore Medical Journal. 49(11): 330-332.Srinivasan, S., Ambler, G.R., Baur, L.A., Garnett, S.P. and Tepsa, M. (2006). Randomized, controlled trial of metformin for obesity and insulin resistance in children and adolescents: improvement in body composition and fasting insulin. Journal of Clinical Endocrinology and Metabolism. 91: 2074-2080. Sterne, J. (1957). Du nouveau dans les anti ... Continue reading---
