Pharmacological Studies on Drug-Drug Interactions between Antidiabetic Drug (Glibenclamide) and Selective Anti-HIV Drug (Lamivudine) in Rats and Rabbits

 

Bhavimani Guru¹*, Nitin M.²

¹Research Scholar, Dept. of Pharmacology, HKES MTRIPS, Kalaburagi, Karnataka, India-585105

²Professor & Head, Dept. of Pharmacology, HKES MTRIPS, Kalaburagi, Karnataka, India-585105

 

ABSTRACT:

The studies were conducted in normal and diabetic rats, and in normal rabbits to find out the influence of lamivudine on pharmacodynamics of glibenclamide. Rats were divided into four groups each containing six. Group-I: treated with therapeutic dose (TD) of lamivudine (5.4mg/200g body weight). Group-II: treated with therapeutic dose of glibenclamide (0.18mg/200g body weight). Group-III: treated with combination of therapeutic dose of lamivudine and glibenclamide. Group-IV: served as control (acacia suspension l% w/v). Same grouping was done for multiple days of therapeutic dose (MTD) studies (10 days), double therapeutic dose (2TD) and multiple days of double therapeutic dose (M2TD) studies (10 days). Streptozotocin at a dose of 50mg/kg body weight intraperitoneally was used to induce diabetes. Rats with glucose levels more than 200mg/dL were considered as diabetic. The experiment was carried out as described for normal rats. The influence of combination of both the drugs was studied in normal rabbits. A group of normal rabbits were taken and the experiment was carried out as described for normal rats. The results indicate that lamivudine produced significant increase in blood glucose, thereby it alters the hypoglycaemic activity of glibenclamide in normal rats, diabetic rats as well as in normal rabbits. As the interaction has been found in two dissimilar species that is rats and rabbits it indicates, it may occur in humans also.

 

 

 

INTRODUCTION:

Drug research and introduction of new molecules is a continuous process. Many a times clinicians face newer challenges in managing either a single disease or simultaneously occurring different diseases. Thus, polypharmacy and multiple drug therapy may become inevitable. This can pose a risk of drug-drug interaction. Simultaneous use of several drugs often leads to drug-drug interactions.¹ The prediction of drug-drug interactions is of clinical importance for selecting regimens and adjusting doses to ensure safety and efficacy of drug combination.²

 

The term diabetes mellitus is defined as a group of syndromes characterized by hyperglycaemia, altered metabolism of lipids, carbohydrates and proteins and an increased risk of complications from vascular diseases.³ This has become a major threat to public health resources throughout the world. Diabetes mellitus requires lifelong treatment with drugs coupled with diet control and exercise.⁴ Conventionally diabetes mellitus is classified as, type I diabetes mellitus which is an autoimmune disorder that leads to hypoinsulinaemia and hyperglycaemia.⁵ On the other, type II is non-insulin dependent diabetes that is characterized by decreased insulin and decreased sensitivity of cells to the released insulin. Insulin is the drug of choice in type I diabetes and sulfonylureas are the drugs of choice in type II diabetes mellitus. Sulphonylureas are the most widely used drugs for diabetic conditions. Among sulphonylureas glibenclamide is one of the drugs of choice because of its low dose and long duration of action.⁶

 

The HIV or retrovirus is a Lentivirus that causes Acquired Immunodeficiency Syndrome (AIDS). It may affect diabetes too. Lamivudine is the widely used drug in the treatment of AIDS. Glibenclamide and lamivudine are metabolised by cytochrome P450⁷. Thus, there is a possibility of concomitant administration of glibenclamide and lamivudine in diabetic patients associated with AIDS which may lead to drug-drug interaction with altered therapeutic activity.

 

MATERIAL AND METHODS:

Pure sample of Glibenclamide, Lamivudine were gift sample from Cipla R and D Mumbai, Glucometer was purchased from general medical store for glucose estimation.

 

Experimental Procedure:

Inbred Swiss adult albino rats of either sex weighing between 180-220g and rabbits 1.5-2.2 kg were selected and used for the study. They were procured from Central Animal House of MTRIPS. IAEC permission was obtained for the conduction of experiments. They were maintained on standard food pellets and potable water with temperature of 25 ± 1 C and relative humidity of 35-50 %.

 

Study in normal Rats:

The rats were fasted for 18 h prior to the experiment with water ad libitum. The animals were divided into 4 groups each containing 6 rats. Group I was treated with therapeutic dose of lamivudine i.e., 5.4mg/200g body weight. Group II was treated with therapeutic dose of glibenclamide i.e., 0.18mg/200g body weight. Group III was treated with combination of therapeutic dose of lamivudine and glibenclamide. Group IV was maintained as control and treated with 1 ml acacia suspension. Same grouping was done for multiple days of therapeutic dose studies (10 days), double therapeutic dose and multiple days of double therapeutic dose studies (10 days). In combination group, dose of lamivudine was administered first followed by dose of glibenclamide after an interval of 30 min. The blood samples were collected from tail vein and the blood glucose levels were estimated at 0, 1, 2, 4, 6 and 8 h. intervals using glucometer (Accu-Check glucometer and Accu-Check strips)

 

Study in diabetic Rats:

Streptozotocin treatment (Induction of diabetes):⁸

Preparation of 0.1M-citrate buffer solution was done by accurately weighing 1.49 g of trisodium citrate. It was dissolved in 100ml of cold distilled water and the necessary pH (4.5) was adjusted with concentrated HCL. A solution of streptozotocin (STZ) was prepared by dissolving the weighed quantity of STZ in 0.1M freshly prepared ice-cold citrate buffer (pH 4.5) solution. The solution of STZ so prepared was administered in the volume of 0.5mL/200g. The selected rats were fasted overnight. Fasting blood glucose was measured and the rats were weighed before administering STZ 50mg/kg intraperitoneally. Blood glucose levels were determined after 2 day of administering STZ to confirm hyperglycemia. After the injection, they were provided with 10% dextrose solution through feeding bottles to prevent sudden hypoglycemic shock due to the sudden release of stored insulin from the destroyed cells. diabetic rats were selected. The experiment was carried out as described for normal rats. Same grouping was done for multiple days of therapeutic dose studies (10 days). The blood samples were collected from the tail vein and glucose was estimated at 0, 1, 2, 4, 6 and 8 h. intervals using glucometer.

 

Study in normal Rabbits:

Albino rabbits of either sex weighing between 1.5-2.2 kg were selected. A group of rabbits (n=5) were taken and the experiment was designed in different stages after fasting previously for 18 h. Stage I: treated with therapeutic dose of lamivudine (42mg/1.5kg body weight). Stage II: after wash out period of 5 half lives, they were treated with therapeutic dose of glibenclamide (0.7mg/1.5kg body weight). Stage III: after wash out period of 5 half lives, they were treated with combination of lamivudine and glibenclamide. Stage IV: served as control (acacia suspension 1%w/v). The blood samples were collected from the marginal ear vein and the blood glucose levels were estimated at 0, 1, 2, 4, 6 and 8 h. intervals using glucometer.

 

STATISTICAL SIGNIFICANCE:

The blood glucose was estimated and percentage change in blood glucose levels were calculated by applying unpaired Student’s t-test for rats and paired Student’s t-test for rabbits. P<0.05 were considered as significant.

 

RESULTS AND DISCUSSION:

The mean percent blood glucose change of therapeutic dose (TD), double therapeutic dose (2TD), multiple days of therapeutic dose (MTD), multiple days of double therapeutic dose (M2TD) are given in tables 1,2,3 and 4.

 

 

Table 1: Mean blood glucose level and percentage change in blood glucose levels in normal rats treated with therapeutic dose (TD) and double therapeutic dose (2TD) of Lamivudine, Glibenclamide and Combination.

* p <0.05, **p <0.01, ***p <0.001, ****p <0.0001.  BGL – blood glucose level, ↑ — Increase, ↓ — Decrease.

 

Table 2 : Mean blood glucose level and percentage change in blood glucose levels in normal rats treated with multiple days of therapeutic dose (MTD) and multiple days of double therapeutic dose (M2TD) studies of Lamivudine, Glibenclamide and Combination (10 days).

 

Table 3 : Mean blood glucose level and percentage change  in blood glucose levels in diabetic rats treated with therapeutic dose (TD) and multiple days of therapeutic dose (MTD) of Lamivudine,  Glibenclamide and Combination.

 

Table 4: Mean blood glucose level and percentage change in blood glucose levels in normal rabbits treated with therapeutic dose (TD) of Lamivudine, Glibenclamide and Combination.

 

The peak rise in blood glucose level in normal rats treated with TD of lamivudine was 9.71% at 1^st h. In the control group there was 1.64% percent reduction in blood glucose at 1^st h. The influence of lamivudine in combination with glibenclamide produced a peak fall of 23.24% at 8^th h. whereas, glibenclamide alone produced a peak fall of 47.17% at 8^th h. indicating lamivudine has affected blood glucose level that is statistically significant with P< 0.0001.

 

The peak rise in blood glucose level in normal rats treated with multiple days of TD of lamivudine (10 days) was 15.62% at 1^st h. In the control group there was 1.56% percent reduction in blood glucose at 1^st h. The influence of lamivudine in combination with glibenclamide produced a peak fall of  27.25% at 8^th h. whereas, glibenclamide alone produced a peak fall of 51.11% at 8^th h. indicating lamivudine has affected blood glucose level that is statistically significant with P< 0.0001.

 

The peak rise in blood glucose level in normal rats treated with 2TD of lamivudine was 4.38% and 7.80% at 1^st and 2^nd  h. respectively. In the control group there was 2.16% and 3.85% percent reduction in blood glucose at 1^st and 2^nd h. respectively. The influence of lamivudine in combination with glibenclamide produced a peak fall of 39.42% at 8^th h. whereas, glibenclamide alone produced a peak fall of 58.89% at 8^th h. indicating lamivudine has affected blood glucose level that is statistically significant with P< 0.05.

 

The peak rise in blood glucose level in normal rats treated with multiple days of 2TD of lamivudine (10 days) was 6.99% and 14.26% at 1^st and 2^nd h. respectively. In the control group there was 1.23% and 2.77% percent reduction in blood glucose at 1^st and 2^nd h. respectively. The influence of lamivudine in combination with glibenclamide produced a peak fall of 43.57% at 8^th h. whereas, glibenclamide alone produced a peak fall of 57.45% at 8^th h. indicating lamivudine has affected blood glucose level that is statistically significant with P< 0.001.

 

The peak rise in blood glucose level in diabetic rats treated with TD of lamivudine was 4.16% at 1^st h. The influence of  lamivudine in combination with glibenclamide produced a peak fall of 8.11% at 8^th h. whereas, glibenclamide alone produced a peak fall of 19.69% at 8^th h. indicating lamivudine has affected blood glucose level but it is not statistically significant.

 

The peak rise in blood glucose level in diabetic rats treated with multiple days of TD of lamivudine (10 days) was 4.98% at 1^st h. The influence of lamivudine in combination with glibenclamide produced a peak fall of 10.11% at 8^th h. whereas, glibenclamide alone produced a peak fall of 18.19% at 8^th h. indicating lamivudine has affected blood glucose level but it is not statistically significant.

 

The peak rise in blood glucose level in normal rabbits treated with TD of lamivudine was 22.21% at 1^st h. In the control group there was 1.80% percent reduction in blood glucose at 1^st h. The influence of lamivudine in combination with glibenclamide produced a peak fall of 18.88% at 8^th h. whereas glibenclamide alone produced a peak fall of 47.08% at 8^th h. indicating lamivudine has affected blood glucose level that is statistically significant with P< 0.05.

 

Since infectious diseases are more common in diabetes, AIDS is likely to occur in diabetics as a result the use of anti-HIV drugs along with antidiabetic drugs is also more. For finding the information about drug interaction between glibenclarnide and lamivudine, It was planned to find the influence of the lamivudine on glibenclamide induced hypoglycaemia in normal rats. But the antidiabetic drugs are used only in diabetic condition and not in normal condition. Hence to check the validity of the interactions seen in normal rats, the study was repeated on diabetic rats. The interaction was considered to be significant if it exists in diabetic condition also. Diabetes was induced using streptozotocin a diabetogenic agent. It was reported that lamivudine also involves the same cytochrome P450 enzyme which was involved in the metabolism of glibenclamide. Thus lamivudine alters the metabolism of glibenclamide leading to the lower the concentrations of glibenclamide in the blood causing hyperglycaemia. Since the combination was found to produce pharmacodynamic interaction of lamivudine on glibenclamide in two dissimilar species, it is likely to occur in humans also.

 

CONCLUSION:

The studies of interaction of lamivudine with glibenclamide produced statistically significant pharmacodynamic interaction in normal rats. lamivudine produced hyperglycaemia when administered alone and decreased the effect of glibenclamide. The interaction studies of lamivudine in diabetic rats produced similar results as observed in normal rats. The treatment of lamivudine, produced similar results on glibenclamide pharmacodynamics in normal rabbits. Since the interaction occurred in two dissimilar species namely rats and rabbits, they are likely to occur in humans also.

 

ACKNOWLEDGEMENT:

The researchers are thankful to the authorities of HKES MTRIPS, Kalaburagi for the facilities provided.

 

 

REFERENCES:

1.       Steel, K.K., Gertman, P.M., Cresienze, C., Andersen J. Latrogenic illness on a general medical service at a university hospital. N Eng J Med 1981; 34, 638-642.

2.       Pirmohammed, M., James, S., Meakin, S., Green C., Scott, A.K., Walley, T.J., Adverse drug reaction as cause of admission to hospital: Prospective Analysis of 18820 Patients.; BMJ 2004; 329, 15-19.

3.       Arky R.A. clinical correlates of metabolic derangement of Diabetes Mellitus. In complications of diabetes mellitus. W.B. Saunders, Philadelphia, 1982; 16-20.

4.       Zimmet, P.Z., Diabetes epidemiology as a tool to trigger diabetes research and care. Diabetologia 1991; 42, 499-518.

5.       Bach, J. F. Insulin dependent diabetes mellitus as β-cell targeted disease of immunoregulation. J. Autoimmunol 1995; 8, 439-463.

6.       Athena Philis-Tsimikas, Guillaume Charpentier, Per Clauson, Gabriela Martinez Ravn, Victor Lawrence Roberts and Birger Thorsteinsson. Comparison of Once Daily Insulin Detemir with NPH Insulin Added to a Regimen of Oral Antidiabetic Drugs in poorly controlled Type 2 Diabetes. Clinical therapeutics 2006; 28, 1569-1581.

7.       Goodman and Gilman. The pharmacological Basis of Therapeutics. 10^th ed. New York: McGraw Hills, Medical Publication; 2008.

8.       Venkateswaran S, Pari L. Effect of Coccinia indica leaves on antioxidant status in streptozotocin-induced diabetic rats. J Ethnopharmacol 2003; 163-168.

 

 

 

 

 

 

Received on 10.07.2017       Modified on 18.08.2017

Accepted on 21.09.2017      ©A&V Publications All right reserved