Comparative study of In-Vivo effects of Glipizide and Metformin HCl on plasma concentration of Aminophylline in healthy rabbits

Palaksha MN¹, Tamizh Mani T¹, Manjunatha E²*, G P Senthil Kumar¹

¹Bharathi College of Pharmacy, Bharathinagara, Mandya-571422.

²Siddaganga College of Pharmacy, Tumkur-572102.

*Corresponding Author E-mail: manjupharma@gmail.com

ABSTRACT:

A drug interaction is the modification of the effects of one drug in the presence of other drug. The interaction can modify the drugs by forming chemical complex, nullify the action, increase the effect, decrease the effect, induce or inhibit the hepatic metabolism and elimination rate of the one drug in presence of other drug. The in-vivo effects of Glipizide and Metformin Hcl on plasma concentration of Aminophylline have been studied in rabbits. In this study, the plasma concentration of Aminophylline was determined by UV spectroscopic method using calibration curve, after oral single administration of Aminophylline alone and with Glipizide and Metformin HCL in rabbits was determined. The results have shown that Aminophylline can enhance both Glipizide and Metformin HCl plasma concentration in rabbits. The data obtained would help us to suggest that Glipizide as well as Metformin HCl may result into compatible combination therapies with Aminophylline an antiasthmatic drug is useful in the treatment of diabetic patients.

KEYWORDS: Drug-Interaction, Metformin, Aminophylline, Glipizide, UV-Spectrophotometer.

INTRODUCTION:

A drug interaction can be defined as the modification in the effect of one drug by the other drug. The interaction can modify the drugs by forming chemical complex, nullify the action, increase the effect, decrease the effect, induce or inhibit the hepatic metabolism and elimination rate, create an environment (by changing the pH of the stomach or urine, by increasing or decreasing the sensitivity to other drugs) (Nitin M et.al 2011, 2013, Bhavimani Guru 2017) where the other drug failed to exert its effects.

The net result may enhance or diminish effects of one or both the drugs (Cadwallader, D.E. 1985). A drug interaction may be Pharmacokinetic or Pharmacodynamic in nature. Pharmacokinetic interactions influence the deposition of a drug in the body and involve the effects of one drug on the absorption, distribution, metabolism and excretion of another drug. Due to large inter and intra patient variability in drug disposition, pharmacokinetic interaction seldom produces serious clinical consequences. Pharmacodynamic interactions are related to the pharmacologic activity of the interacting drugs. These are more frequent mechanism of pharmacodynamic interactions includes synergism, antagonism, altered cellular transport and effects on receptor sites.

Aminophylline is the Ethylenediamine salt of theophylline. After ingestion, Theophylline is released from Aminophylline, Theophylline competitively inhibits type III and type IV phosphodiesterase (PDE), the enzyme responsible for breaking down cyclic AMP in smooth muscle cells, possibly resulting in bronchodilation. Theophylline also binds to the adenosine A2B receptor and blocks adenosine mediated bronchoconstriction. It has 60% plasma protein binding. It is given daily in a dose of 250-500mg/day 1-2doses. Aminophylline is metabolized in the liver via oxidation, demethylation, acetylation and is excreted in the urine and other metabolites with only about 1% unchanged (Sawynok, J. 1995. Martindale: 2005, Sandhoshini Meena. S 2019).

Glipizide is a oral hypoglycemic drug. Glipizide, like other sulfonylurea drugs, is an insulin secretagogue, which works by stimulating the insulin release from the pancreatic beta cells thereby increasing the plasma concentrations of insulin (Sola et al., 2015). It has 90% plasma protein binding. The metabolites and a small amount of unchanged drug are excreted in the urine.

Metformin hydrochloride is a biguanide, oral hypoglycemic agent. It is given by mouth in the treatment of type 2 diabetes mellitus and is the drug of choice in obese patients. Metformin's mechanisms of action are unique from other classes of oral antihyperglycemic drugs. Metformin decreases blood glucose levels by decreasing hepatic glucose production (gluconeogenesis), decreasing the intestinal absorption of glucose, and increasing insulin sensitivity by increasing peripheral glucose uptake and utilization (Rena et al., 2013). It has 90% plasma protein binding. Initial dose is 500 mg two or three times daily or 850mg once or twice daily with or after meals, gradually increased if necessary to 2 to 3g daily (Jajow Swapna et.al 2012, Sweetman, 2005).

The present study was aimed to evaluate the possible In-Vivo effects of Glipizide and Metformin-HCl on plasma concentration of Aminophylline in healthy rabbits.

MATERIALS AND METHODS:

Drugs and chemicals used:

Aminophylline, Glipizide, Metformin Hydro chloride, were obtained from the Cipla laboratories Pvt. Ltd Mumbai (GIFTED SAMPLES).

Instruments used:

UV-visible spectrophotometer (ShimadzuUV-1800), Centrifuge machine, PH meter, Shimadzu electronic balances.

Animals:

12 healthy male rabbits weighing 2 to 3kg were acclimatized to experimental room at temperature 23±2ºc, controlled humidity condition (50 to 55%) and 12hr light and 12hr dark cycle. They were caged with a maximum of two animals in poly propylene cage and were fed with standard food pellets and water and libitum, all the studies conducted were approved by the institutional animal ethical committee of Bharathi College of Pharmacy, Bharathinagara. According to prescribed Guidelines of Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), Government of India.

Preparation of calibration curve for Aminophylline: For preparing a standard calibration curve 100mg of Aminophylline was taken with 10ml of phosphate buffer of 7.4 pH. This was used as a stock solution, to prepare solution of Aminophylline containing 100, 200, 500, 750, 1000µg, then observed at 269nm.

Test Animals and Administration of Drugs:

There are 12 adult rabbits of 2-3kg body weight were used. They were kept rest for 7 Days with normal diet. These rabbits were divided into 4 groups each group having 3animals, marked as 1, 2 and 3 and 4^th group respectively. Aminophylline alone is used and its 1:1 mixture with Glipizide and Metformin HCL were administrated by oral route in each group.

Aminophylline, Glipizide and Metformin HCL were dissolved in distilled water separately. These stock solutions were diluted to obtain desired strengths and buffered, while diluting to working solutions. Aminophylline -10mg/kg body weight, Glipizide -2mg/Kg body weight, Metformin Hcl^--30mg/kg body weight.

Drug treatment:

Animals were over night fasted before drug administration, blood samples were collected from the marginal ear vein at 0, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 hrs after drug administration.

All Blood samples were protected from light and immediately centrifuged at 3000 rpmfor 10 min and the plasma Samples were separated and kept in deep freezer until take the absorbance. The plasma samples were subjected to serial dilutions. Each of the solutions was observed at 269nm.

Group	Treatment
I	Treated Aminophylline (CONTROL) Orally
II	Treated Aminophylline +Glipizide Orally
III	Treated Aminophylline +Metformin Hcl Orally
IV	Treated Aminophylline +Glipizide+MetforminOrally

RESULTS:

The in-vivo effects of Glipizide and Metformin Hcl on plasma concentration of Aminophylline have been studied by observing the change in plasma concentration of Aminophylline in rabbits. In this study plasma concentration of Aminophylline by UV spectroscopic method using calibration curve was studied and the results were given in table no.1 and Figure. 1.

Table No. 1 Absorbance of Aminophylline

S. No.	Concentration in µg	Mean Absorbance value	Standard deviation
1	0	0	0.000619
2	200	0.198	0.004619
3	400	0.388	0.000577
4	600	0.603	0.019858
5	800	0.798	0.023388
6	1000	0.996	0.001914
7	slope	0.001	0.001914
8	Intercept	0.0025	0.012437
	Correlation	0.9998	0.000287

Figure. No. 1 Calibration curve of Aminophylline

The peak plasma concentration of Aminophylline is 758.36µg which was obtained after 1h of oral administration of Aminophylline alone are given in the Table no.2 and Fig no.2.

Tableno.2. Plasma concentration of Aminophylline

S. No.	Time in Hours	Amount of Drug present in Plasma
1	0	0
2	0.5	310.60
3	1	758.36
4	2	649.45
5	3	498.18
6	4	425.57
7	5	340.86

Figure no.2.Aminophylline

The oral concomitant administration of Aminophylline and Glipizide makes a significant change in plasma concentration of Aminophylline this case the peak plasma concentration of Aminophylline is 764µg. Which is significantly slightly higher than that of Aminophylline when administration alone. They are given in the Table no.3 and represents in Fig.no.3.

Table No.3. Plasma concentration of Aminophylline + Glipizide

S. No.	Time in Hours	Amount of Drug present in Plasma
1	0	0
2	0.5	206.91
3	1	521.84
4	2	764.41
5	3	440.53
6	4	213.47
7	5	156.14

Figure No. 3. Aminophylline + Glipizide

The Results shown that the concurrent administration of Aminophylline and Metformin Hcl make a slight change in plasma concentration of Aminophylline in this case the peak plasma concentration of Aminophyllne is 933.84 µg. as shown in the below table no.4 and figure no.4.

Figure 4. Aminophylline + Metformin HCL

Table.4. Plasma concentration Aminophylline + Metformin HCL

S. No.	Time in Hours	Amount of Drug present in plasma
1	0	0.00
2	0.5	461.84
3	1	933.83
4	2	824.92
5	3	655.50
6	4	492.13
7	5	425.57

The concurrent administration of Aminophylline, Metformin HCL and Glipizide does not make any change in plasma concentration of Aminophylline in this case the peak plasma concentration of Aminophyllne is 853.36µg, when co-administration. They are given in the table no.5 and represents in fig.no.5.

Table. 5. Aminophylline + Metformin HCL+ Glipizide

S. No.	Time in hrs	Amount of drug present in plasma
1	0	0
2	0.5	361.87
3	1	853.84
4	2	734.92
5	3	565.50
6	4	398.13
7	5	315.57

Figure 5. Aminophylline + Metformin HCL+ Glipizide

DISCUSSION:

The in-vivo effects of Glipizide and Metformin Hcl on plasma concentration of Aminophylline have been studied by observing the change in plasma concentration of Aminophylline in rabbits in this study the plasma concentration of Aminophylline was determined by UV spectroscopic method using calibration curve after oral single administration of Aminophylline alone and with Glipizide and metformin HCl in rabbits (Rahat et al., 1999, Bari et al., 2000)

The determination of plasma concentration of Aminophylline in rabbits by UV spectroscopic method shows that concurrent administration of Aminophylline and has not found any significant change in concentration of aminophylline. Whereas Aminophylline and Metformin Hcl make significant changes in plasma concentration of Aminophylline.

In this study Metformin HCl increased the plasma concentration of Aminophylline. This is due to the competitive protein binding between the Aminophylline and Metformin HCl. Since the protein binding of aminophylline is 60% i.e, a competitive inhibition of the binding to plasma protein by Glipizide increase the plasma concentration of Aminophyllne. Such interactions of the drugs that affect the binding of plasma protein and subsequently change the plasma concentration of the drugs are very vital and to be given priority before formulating drug therapy. Since, drug displaced from plasma protein will redistribute into its full potential volume of distribution, the plasma concentration of free drug in plasma and tissues after redistribution may be change the pharmacokinetics properties of the drug and therapy may affect its pharmacological and toxic effects. (Gilman et al.,1991) Milon and Hossain (2009), Rahman and Hossain (2008) and Salam and Hossain (2001) are engaged in the study of interaction between oral anti diabetic drugs and other agents .

Xanthenes consumption has been extensively studied in relation to various diseases but not until recently has it been examined in relation to risk of type -2 diabetes (van dam and hu, 2005).

In this study the plasma concentration of Aminophyllne in rabbits by UV spectroscopic method shows that concurrent administration of Metformin HCl significantly increases the plasma concentration of Aminophyllne but administration of Glipizide in rabbits showed a slight change in plasma concentration of Aminophyllne. It was observed that Glipizide lowered the affinity of protein binding of Aminophyllne hence an increase in volume of distribution of Aminophyllne might be occurred with Glipizide.

CONCLUSION:

Combination therapy is a useful and common practice in modern medical science, where two or more drugs are administered concurrently. The results in this study have shown that both Glipizide and Metformin HCl can enhance plasma concentration of Aminophylline in rabbits. The data obtained would help us to suggest that Glipizide as well as Metformin HCl may result into compatible combination therapies with Aminophylline, which is useful in the treatment of diabetic patients.

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Received on 05.11.2019 Modified on 07.12.2019

Asian J. Pharm. Res. 2020; 10(2):62-66.

DOI: 10.5958/2231-5691.2020.00012.X