DOI: http://dx.doi.org/10.26510/2394-0859.pbe.2017.38

Research Article

Effect of lopinavir and efavirenz on pharmacokinetics and pharmacodynamics of glibenclamide in diabetic rats

Prashanth Vennapanja, Ramarao Ajmera*

University College of Pharmaceutical Sciences, Kakatiya University, Warangal, Telangana, India

*For correspondence

Dr. Ramarao Ajmera,

University College of Pharmaceutical Sciences, Kakatiya University, Warangal, Telangana, India. Email: ramaraoajmera @gmail.com

 

 

 

 

 

 

 

Received: 09 October 2017

Revised: 06 November 2017

Accepted: 19 November 2017

ABSTRACT

Objective: The aim of the study is whether the impact of Efavirenz and Lopinavir will increase the plasma level of Glibenclamide or not. Efavirenz and Lopinavir is an antiretroviral drug to treat HIV AIDS and inhibits cytochrome P450-3A4. Multiple CYP isoforms are involved in the metabolism of Glibenclamide like CYP2C8 and CYP3A4. Hence there is more possibility of Efavirenz and Lopinavir to inhibit the metabolism of Glibenclamide by inhibiting CYP 3A4.

Methods: Efavirenz and Lopinavir (10 mg/kg,p.o.) alone and along with Glibenclamide (10 mg/kg, p.o.) was given to normal and diabetic rats. PK/PD parameters were studied. In the rats co-treated with Efavirenz and Lopinavir and Glibenclamide.

Results: The pharmacokinetic parameters like clearance of Glibenclamide was reduced, peak plasma concentration, area under the plasma concentration time curve and elimination half-life were significantly increased when compared to pioglitazone treated rats.

Conclusions: This study revealed that lopinavir and efavirenz affected the disposition of Glibenclamide in rats probably by the inhibition of CYP3A4, leading to increasing Glibenclamide concentrations that could increase the efficacy of Glibenclamide or it may causes severe hypoglycemia. Therefore, its warrants to use relatively less dose of Glibenclamide than the normal dose.

Keywords: Lopinavir, Efavirenz, Glibenclamide, Diabetic rats, Drug-drug interactions

Introduction

Pharmacokinetic drug-drug interactions (DDIs) are unfavorable clinical events, which are caused by abnormally increased or decreased drug concentrations in the body as a consequence of co-administration of other drug(s) and sometimes its metabolites at the effective sites within the body.1 The relationship between drug admini-stration and response is divided in to two phases. Pharmacokinetic (PK) phase, which related to the body's effect on the drug and pharmacodynamic phase, which related to the drug effect on the body. Patients often receive multiple medications therapy simultaneously, in diseases such as diabetes, cancer and AIDS etc., which demand the combination therapy, which works better than an individual drug alone. In other cases, the patient is suffering from several conditions, each of which is being treated with one or more drugs, in this situation there is many potential sites for interaction that exist within the body. An interaction may occur between them by either altered Pharmacokinetics or Pharmaco-dynamics (PD) of one drug by another.2,3 In the present study, we have evaluated the effect of lopinavir and efavirenz (anti HIV drugs) on pharmacokinetic and pharmacodynamics of glibenclamide (antidiabetic drug) in diabetic rats.

Materials and Methods

Materials

Lopinavir, efavirenz and glibenclamide are the gift samples from Dr Reddy Labs (Hyderabad, India). Alloxan monohydrate was purchased from Sigma Aldrich (MO, USA). Glucose kits of Span diagnostics were procured from local suppliers. The HPLC grade methanol and ammonium acetate (Merck, Mumbai, India. All other chemicals used were of analytical grade. The drug analysis was carried out using HPLC system (Shimadzu 10AT/Vp, Kyoto, Japan) having Rheodyne injector port (20 μl loop), and UV/vis detector (SPD 10A Vp). The data interpretation was done with LC-solutions (Shimadzu, Kyoto, Japan) data acquisition software.

Animals

Female Wister rats weighing between 180-230 g, procured from Mahaveera Enterprises (Hyderabad, India) were used in the study. They were maintained under standard laboratory conditions at ambient temp of 25 ±20 C with 45-55% relative humidity and a 12 h light/dark cycle. They were fed with standard pellet diet (Mahaveerar Enterprises Pvt. Ltd, Hyderabad, India) and water ad libitum. The prior approval for conducting the experiments in rats wasobtained from our Institutional Animal Ethics Committee (IAEC/02/UCPSC/KU/2010).

Study design

Induction of diabetes in rats

Diabetes was induced in rats by the administration of alloxan monohydrate in ice cold normal saline150 mg/kg bd wt intraperitoneally.4-9 After 72 hr, sample was collected from rats by via jugular vein of all surviving animals and the serum was analyzed for glucose levels. Rats with blood glucose levels of 300 mg/dl and above were considered as diabetic and selected for the study.

Pharmacokinetic and pharmacodynamic interaction study in normal and diabetic rats

Rats were divided into 6 groups each for both normal and diabetic separately (n=6). Following an overnight fast, rats were divided into 6 groups (n=6). The rats were treated as following. Group1 (control)-Treated with normal saline solution, p.o; Group2-The rats were induced diabetes; Group 3The rats were induced diabetes and treated with glibenclamide (5 mg/kg) for 5 days. p.o; Group 4 The rats were induced diabetes and treated with glibenclamide and lopinavir (10 mg/kg) for 5 day. p.o; Group 5 -The rats were induced diabetes and treated with glibenclamide and efavirenz (10 mg/kg). For 5 days. p.o; Group 6. The rats were induced diabetes and treated with glibenclamide, lopinavir and efavirenz (10 mg/kg) for 5 day p.o. Blood samples (0.5 ml) were collected from via jugular vein at time intervals 0, 0.5, 1, 2, 4, 8, and 24 h post dose. Whole blood from donor rats was infused into each study rat to maintain blood volume lost due to sample collection.10-12 Serum was separated by centrifugation at 8000 rpm for 10 min using Biofuge-13 (Heraeus Instruments, Germany). And blood glucose levels were determined using glucose oxidase peroxidase (GOD POD) method by measuring optical density spectro-photometrically at 510 nm and remaining serum was stored in vials at -20o C until further analysis.13-15

Glucose reduction calculations

Percentage Reduction in BGL={(IBGL – FBGL)/ IBGL}×100

Where BGL = blood glucose level; IBGL = initial blood glucose level; FBGL = final blood glucose level.

Data analysis

Pharmacokinetic data analysis

The maximum plasma concentration (Cmax), time needed to reach the maximum plasma concentration (Tmax), area under the concentration time curve (AUC0–8), mean residence time (MRT), elimination rate constant (Kel), clearance and half life (T1/2) were calculated using non-compartmental pharmaco-kinetic model of WinNonlin-4.0.

Statistical analysis

All the means are presented with their standard deviation (mean±SD). The pharmacokinetic parameters of glibenclamide groups were compared using one-way ANOVA, followed by post hoc Dunnett test. An unpaired Student's t-test was used to determine the significant difference between the percentage glucose reduction values and pharmacokinetic parameters of glibenclamide in control and lopinavir, efavirenz treated groups. P<0.05 was considered statistically significant.

Results and Discussion

Effect of lopinavir, efavirenz, on the hypoglycemic action of glibenclamide

All the animals which received alloxan injection developed diabetes. The rats that were made diabetes had higher glucose concentration than control non-diabetic animals (shown in Figure 1). It was reported that elimination half-life of glibenclamide was 6.4 h.16 Therefore, in this study, we monitored the plasma glucose levels at 1, 2, 4, 8, 12 and 24 h after final administration to observe the hypoglycemic effect of glibenclamide.

Figure 1: Plasma glucose concentration in alloxan induced diabetic rats administered with glibenclamide (G), glibenclamide+lopinavir (G+L), glibenclamide+efavirenz (G+E) and glibenclaide+lopinair+efavirenz (G+L+E). Data were expressed as mean±S.E.M. (n=6).

Pharmacodynamics analysis

Glibenclamide

Glibenclamide significantly decreased plasma glucose level at 4 h and maintained the hypoglycemic effect during 2-4 h after final treatment, plasma glucose concentration at 4 h was decreased by 72% vs the diabetic rats (p<0.05). lopinavir, efavirenz, lopinavir +efavirenz itself did not show significant effect on plasma glucose content vs alloxan treatment, however, plasma glucose level in rats co-treated with lopinavir, efavirenz and glibenclamide was decreased by 60% (p<0.001), 72% (p<0.001) and 61% (p<0.1) at 2, 4 and 8 h after final administration, respectively, as compared with the diabetic animals; plasma glucose content at 4 h was significantly reduced by 72% (p<0.001) vs glibenclamide treated rats.

Glibenclamide + lopinavir

Glibenclamide significantly decreased plasma glucose level at 4 h and maintained the hypoglycemic effect during 2–4 h after final treatment, plasma glucose concentration at 4 h was decreased by 59% vs the diabetic rats (p<0.01). lopinavir, efavirenz, lopinavir +efavirenz itself did not show significant effect on plasma glucose content vs alloxan treatment, however, plasma glucose level in rats co-treated with lopinavir, efavirenz and glibenclamide was decreased by 49% (p<0.001), 59% (p<0.01) and 55% (p<0.01) at 2, 4 and 8 h after final administration, respectively, as compared with the diabetic animals; plasma glucose content at 4 h was significantly reduced by 59% (p<0.01) vs glibenclamide-treated rats.

Table 1: Mean pharmacokinetic parameters of glibenclamide in alloxan-induced diabetic rats administered with glibenclamide (G) alone and co-administered with lopinavir (G+L), efavirenz (G+E) and lopinavir + efavirenz (G+L+E).

Parameters G G+L G+E G+L+E
Auc 29.5±1.13 15.23±1.24 90.81±1.16 111.42±1.23
K 1.8±0.11 4.5±0.23 5.63±0.23 6.11±0.23
Cl 0.16±0.64 0.32±0.54 0.05±0.43 0.04±0.11
Tmax 2.6±0.83 6.61±0.23 8.12±0.23 8.81±0.23
Cmax 3.07±0.73 0.84±0.68 4.11±0.93 4.64±1.33

Figure 2: Mean plasma concentration–time curve of glibenclamide in alloxan-induced diabetic rats administered with glibenclamide (G) alone and co administered with lopinavir (G+L), efavirenz (G+E), lopinavir + efavirenz (G+L+E).

Glibenclamide + efavirenz

Glibenclamide significantly decreased plasma glucose level at 4 h and maintained the hypoglycemic effect during 2–4 h after final treatment, plasma glucose concentration at 4 h was decreased by 68% vs the diabetic rats (p<0.001). lopinavir, efavirenz, lopinavir +efavirenz itself did not show significant effect on plasma glucose content vs alloxan treatment, however, plasma glucose level in rats co-treated with lopinavir, efavirenz and glibenclamide was decreased by 47% (p<0.001), 68% (p<0.001) and 55% (p<0.001) at 2, 4 and 8 h after final administration, respectively, as compared with the diabetic animals; plasma glucose content at 4 h was significantly reduced by 68% (p<0.001) vs glibenclamide-treated rats.

Glibenclamide + lopinavir + efavirenz

Glibenclamide significantly decreased plasma glucose level at 4 h and maintained the hypoglycemic effect during 2–4 h after final treatment, plasma glucose concentration at 4 h was decreased by 77% vs the diabetic rats (p<0.001). Lopinavir, efavirenz, lopinavir +efavirenz itself did not show significant effect on plasma glucose content vs alloxan treatment, however, plasma glucose level in rats co-treated with lopinavir, efavirenz and glibenclamide was decreased by 48% (p<0.001), 77% (p<0.001) and 57% (p<0.01) at 2, 4 and 8 h after final administration, respectively, as compared with the diabetic animals; plasma glucose content at 4 h was significantly reduced by 77% (p<0.05) vs glibenclamide-treated rats.

Pharmacokinetic analysis

Glibenclamide + lopinavir

Mean plasma concentration vs. time curve for glibenclamide was illustrated in Figure 2: For the animals co-treated with lopinavir and glibenclamide Pk values are summarized in Table 1. elimination clearance of glibenclamide was increased by 48.3% while peak plasma concentration (Cmax), area sunder the curve (AUC) were decreased by 72%, 48% respectively, as compared with glibenclamide treated group. The results indicated that lopinavir effect to induction of glibenclamide and led to the reduction of Cmax and AUC.

Glibenclamide+Efavirenz

Mean plasma concentration vs. time curve for glibenclamide was illustrated in Figure 2: For the animals co-treated with efavirenz and glibenclamide, elimination of glibenclamide was decreased by 67% while peak plasma concentration (Cmax), area under the curve (AUC) and elimination half-life (T1/2Ke) were markedly increased by 25%, 67% and 67% respectively, as compared with glibenclamide treated group. The results indicated that efavirenz effect to inhibit the glibenclamide and led to the elevation of Cmax and AUC.

Glibenclamide+Lopinavir+efavirenz

Mean plasma concentration vs. time curve for glibenclamide was illustrated in Figure 2: For the animals co-treated with lopinavir + efavirenz and glibenclamide, elimination of glibenclamide was decreased by 73% while peak plasma concentration (Cmax), area under the curve (AUC) and elimination half-life (T1/2Ke) were markedly increased by 33%, 70% and 70%, respectively, as compared with glibenclamide treated group. The results indicated that lopinavir + efavirenz effect to majorly to the inhibition of the glibenclamide and led to the elevation of Cmax and AUC.

Glibenclamide produces the hypoglycemic effect by stimulating insulin secretion from β cells of pancreatic islets.17 The results in our study showed that the pharmacokinetic process and hypoglycemic effect of glibenclamide altered when co-administrated with lopinavir, efavirenz and lopinavir+efavirenz.

In this study, the diabetic rats shows the peak plasma concentration of glibenclamide was markedly (p<0.05) increased 25% and 33% by the co-treatment with efavirenz, lopinavir +efavirenz and glibenclamide in alloxan-diabetic rats. AUC and T1/2 of glibenclamide were significantly (p<0.05) increased 67% and 73% respectively, by those drugs co-administration. This result indicated that efavirenz could inhibit the metabolism of glibenclamide.

Peak plasma concentration of glibenclamide was markedly (p<0.001) decreased 72% by the co-treatment with lopinavir and glibenclamide in alloxan-diabetic rats. AUC and T1/2 of glibenclamide were significantly (p<0.001) decreased by 48% and 60% respectively, by those two drugs co-administration. This result indicated that lopinavir could induce the metabolism of glibenclamide.

Peak plasma concentration of glibenclamide was markedly (p<0.05) increased 33% by the co-treatment with efavirenz, lopinavir +efavirenz and glibenclamide in alloxan-diabetic rats. AUC and T1/2 of glibenclamide were significantly (p<0.05) increased 70% and 70% respectively, by those two drugs co-administration. This result indicated that lopinavir+efavirenz could majorly inhibit the metabolism of glibenclamide.

Lopinavir is the inducer of CYP2C9 reduces the plasma concentration of the sulfonylureas, glibenclamide. Glibenclamide is most susceptible sulfonylurea to induction. The concomitant use of lopinavir with sulfonylurea glibenclamide may thus worsen blood glucose control.18-20

Efavirenz is the inhibitor of CYP2C9. Inhibition of CYP2C9 elevates plasma concentration of glibenclamide. The concomitant use of efavirenz with glibenclamide may increase the glucose-lowering effect of glibenclamide.

The effects of efavirenz on the pharmacodynamics and pharmacokinetics of glibenclamide suggest that efavirenz affects the metabolism of glibenclamide in alloxan-induced diabetic rats, possibly by the inhibition of CYP2C9. Concomitant use of efavirenz with glibenclamide considerably increases the glucose-lowering effect of glibenclamide.

Conclusions

The effects of lopinavir+efavirenz on the pharmacodynamics and pharmacokinetics of glibenclamide suggest that lopinavir+efavirenz affects the metabolism of glibenclamide in alloxan-induced diabetic rats, possibly majorly by the inhibition of CYP2C9. Concomitant use of lopinavir+efavirenz with glibenclamide considerably increases the glucose-lowering effect of glibenclamide.

Funding: No funding sources

Conflict of interest: None declared

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