Diabetes mellitus, a complex metabolic disorder characterized by chronic hyperglycemia, remains a formidable global health challenge, affecting millions of individuals worldwide [16]. It poses significant medical, economic and social burdens due to its associated complications, including cardiovascular diseases, neuropathy, nephropathy and retinopathy [7,11,16]. The cornerstone of diabetes management involves achieving and maintaining optimal blood glucose levels through lifestyle modifications, pharmacotherapy and in some cases, insulin therapy [7]. The pharmacological armamentarium for diabetes treatment comprises various classes of anti-diabetic drugs, including biguanides (e.g., Metformin), sulfonylureas (e.g., Glipizide), thiazolidinediones (e.g., Pioglitazone), dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g., Sitagliptin), sodium-glucose cotransporter-2 (SGLT2) inhibitors (e.g., Dapagliflozin) and glucagon-like peptide-1 (GLP-1) receptor agonists (e.g., Liraglutide) [3,4,6,7,12,15]. While these medications effectively lower blood glucose levels and improve glycemic control, they often exhibit limitations such as poor aqueous solubility, low bio-availability, short half-lives and dose-dependent adverse effects [3,4,6,7,12,15].

To address these challenges and enhance the therapeutic efficacy of anti-diabetic drugs, researchers have explored various drug delivery systems and formulation strategies [1,2,5]. Among these, micro-encapsulation technology has emerged as a promising approach for improving the stability, bio-availability and targeted delivery of drugs [1,2,5]. Micro-encapsulation involves enclosing active pharmaceutical ingredients (APIs) within microscopic particles or capsules, providing protection from degradation, controlling release kinetics and enabling site-specific delivery [1,2,5].

One notable micro-encapsulation technique gaining attention in the field of diabetes management is Micro-encapsulated Glycation (MCG) [1,5]. MCG technology involves the encapsulation of anti-diabetic drugs within bio-compatible polymers using advanced micro-encapsulation methods [1,5]. These micro-capsules, typically ranging from nanometers to micrometers in size, offer several advantages for drug delivery applications, including controlled release, prolonged therapeutic effect, reduced dosing frequency, and improved patient compliance [1,5].

The rationale behind incorporating anti-diabetic drugs into MCG based formulations lies in the ability of microencapsulation to address key pharmacokinetic challenges associated with conventional dosage forms [1,5]. By encapsulating drugs within polymer matrices, MCG systems protect the active ingredients from enzymatic degradation, pH fluctuations and other environmental factors encountered in the gastrointestinal tract [1,5]. This protective barrier enhances drug stability and bio-availability, ensuring consistent plasma concentrations and sustained pharmacological effects over extended periods [1,5].

Moreover, MCG based formulations can modulate drug release kinetics to achieve desired therapeutic outcomes, such as maintaining euglycemia throughout the day or minimizing postprandial hyperglycemia [1,5]. The tunable release profiles offered by MCG systems allow for customization of dosage regimens tailored to individual patient needs, thereby optimizing treatment efficacy and minimizing adverse effects [1,5].

In the context of combination therapy for diabetes, MCG technology presents a unique opportunity to develop synergistic formulations containing multiple anti-diabetic agents with complementary mechanisms of action [8,9,10,13,14]. By co-encapsulating different classes of drugs within MCG micro-capsules, researchers can exploit potential synergies and address multi-factorial aspects of diabetes pathophysiology, such as insulin resistance, pancreatic ?-cell dysfunction, and glucose uptake abnormalities [8,9,10,13,14].

This article aims to explore the formulation and evaluation of MCG containing combinations of anti-diabetic drugs, providing a comprehensive overview of the principles underlying MCG technology and its applications in diabetes management [1,5,15]. Through a critical analysis of existing literature and research findings, we will examine the potential benefits, challenges and future directions of MCG based formulations in addressing the unmet needs of diabetic patients.

MATERIALS AND METHODS

Metformin purchased from Micro lab, Hosur, Glimepiride purchased from Care formulation, Chennai, Wheat prolamin and Polyvinyl Acetate purchased from Nice chemie, Micro crystalline cellulose and Spray dried lactose purchased from Loba chemie.

Preformulation studies [10]

In the rational development of dosage form preformulation studies are the important and initial step. The aim of preformulation study is to develop information about the drug substances, so that this information would be useful to develop a formulation. It is an essential study for physical and chemical properties of a drug substances alone and in combination with excipients.  Preformulation investigation is designed to identify the physiochemical properties of drugs and excipients that may influence the formulation design, method of formulation pharmacokinetic and bio-pharmaceutical properties of the resulting product. These studies are performed for the preformulation investigation.

Melting point [8]      

The powdered drug is placed in capillary tube and sealed at one end. The capillary tube should be 6-7cm and 1mm in diameter. The substance should be standing in the capillary 3-4mm from the bottom of packed capillary tube. The capillary tube is wetted with the liquid in the bath and placed in iron stand fixed in thermometer. The capillary remains stick over thermometer by itself and is so adjusted that the solid in it stand opposite the middle of the mercury bulb. The thermometer is lowered in a beaker containing paraffin oil and the beaker is heated slowly and kept the uniform temperature of the bath with constant stirring. When the substance in the capillary just shows signs of liquification the burner is removed with constant stirring. The temperature at which the substance melts and becomes transparent is noted.

Preparation of Buffer Solution

Preparation of phosphate buffer (pH 7.4)

Dissolve 8.40 gms of NaH₂PO₄ and 15.62 gm of Na₂PO₄ in 1000 ml of water.

Preparation of acidic buffer (0.1N Hcl)

8.34 ml of con. Hcl was transferred into 1-litre volumetric flask and diluted with 1000 ml distilled water.

Formulation trials,

For the development of an optimized formulation of Medicated chewing gums, several trials were carried out. The general procedures for each layer in all formulation trials are given below.

Formulation Procedure

Dispensing

The materials required for the formulation of Medicated chewing gums are dispensed in order to keep in separate poly bags and they are kept ready for shifting.

Sifting

In order to get a uniform size of particles and well mixing ability, the materials are passed through a selective size ranges of following sieves,

Dry mixing

The API I & II were mixed with wheat prolamin and poly vinyl alcohol in a mortar for about 10 min until the mixing was completed.

Binder solution         

To improve the mechanical strength of the formulation, the binder solution is added. A binder solution is prepared by mixing starch with a sufficient quantity of purified water.

Granulation

The prepared binder solution was added in to the dry mixed materials and finely mixed with the binder and the materials and allowed to pass into #60 sieves.

Drying

Blend of above step was loaded in a rapid dryer and dried at an inner temperature at 50⁰c with the rate of air flow 50, untill the loss on drying the content reaches a range between 1.5%-2.5%.

Lubrication

Along with the above obtained blend talc is added to improve the flow properties.

Pre compression parameters [18]  

The formulated blends has undergone following Preformulation studies,

• • Bulk density
  • Angle of repose
  • Carr’s compressibility studies
  • FT-IR studies
  • Hausner’s ratio

Bulk density (D_b)

The bulk density depends on the particle size distribution, cohesiveness and shape of the particles. 10gm powder is accurately weighted and poured in to a graduated measuring cylinder through a funnel and shaken without tapping, the volume which is measured is called initial bulk. Bulk density is expressed in gm/cc is given by,                   

Bulk density (D _b)   =  Mass of the powder(gm) Bulk volume of powder(cc)

Tapped density (D_t)

10gm of powder is taken for the determination of bulk density is dropped from the particular height in to a measuring cylinder. The cylinder is tapped constantly until there is no change in the volume of the powder and tapped volume was read. The tapped volume is expressed in gm/cc is given by,

Tapped density (D _t)

= Mass of the powder(gm) Tapped  volume of powder(cc)

Angle of repose (?)

The fractional force in a loose powder can be determined by the angle of repose. This is the maximum angle possible between the surface of pile of powder and the horizontal plane. The powder is allowed to fall through the fixed funnel in a definite height. Angle of repose is calculated by measuring the height and radius of the heap of powder produced \8/96/

                          ? = tan ^-1 (h / r)

Carr’s index (CI)

The percentage compressibility of powder is direct measurement of the potential powder arch or the bridge strength and stability. Carr’s index of each formulation was calculated by the equation given below,

CI=Df-DoDf×100

Where, D _f  = tapped density,        D ₀ = bulk density

Hausner’s Ratio (IH)

Is calculated from the DF and d_o using the following expression

Hausner’s ratio (IH) = tapped densitybulk density

       
           
       
Table No, 1. Limits Of Pre Compression Parameters

Post Compression Parameters

Thickness and diameter (narasimha rao r et al., 2013).

The thickness and diameter of MCGs will results in uniform size and shape of the MCGs. This may improve the patient compliance, the MCG thickness were measured in mm by using Vernier caliper.

Hardness

The mechanical strength of the MCGs were performed by the hardness test. The MCGs hardness is measured by the pressure applied on MCG to form a crack along its axis. It is tested by using the Monsanto hardness tester. The MCG was held between a fixed and moving jaw scale was adjusted to zero, pressure was gradually increased until the MCG fractured. The value of the pressure applied to break the MCG in noted. The MCGs were randomly picked and hardness of the MCGs was determined.

1N =7.4 Kg/cm²

Friability

The MCG strength was tested by using the TECH-NU friabilator.20 MCGs was weighed and placed in a friability apparatus. Operate to set the rpm 100 for 4 min, after that take the MCGs and reweigh it. 1 of MCG friability is generally acceptable. The percentage weight loss can be determined by using the following formula.

F = W _initial - (W _final)(W _initial) ×100

Weight variation test

Twenty MCGs are selected randomly, individually weighted in a single pan electronic balance and the average weight was calculated. The uniformity of weight was determined according to IP specification.   From the standard value in  IP,   not more than two of individual weight should deviate from average weight by more than 5  and none deviate more the twice that percentage.

       
           
       
Table No, 3. Weight Variation Test

Drug content analysis

The uniformity of the drug in each formulated MCGs were determined by this assay. The tables are randomly selected, weighted and crushed.  The following assay procedure is performed to determine the drug content in UV spectroscopy API-I (Metformin) at 234 nm and API-II (Glimepiride) at 273 nm against blank. The contents of drug in the formulated MCGs were determined by using the UV spectroscopy.

       
           
       
Table No, 4. Dissolution Condition For The Formulation Trails

The data obtained from the dissolution study was subjected to the analysis to known the release pattern of the drug from the dosage form to analyze the mechanism of release and release rate kinetic of the dosage form and the   data obtained were fitted into,

• Zero order
• First order kinetics
• Higuchi model kinetic
• Korsmeyar-peppas model

Based on the r²- value, the best-fit model was selected.

Zero order kinetics

It describes the system in which the drug release rate is independent of its concentration.

Q_t=Q₀+K₀t

Where,

            Q_t = amount of drug dissolved in time t.

            Q₀= initial amount of the drug in the solution and the

            K₀= zero order release constant.

If the drug release obeys zero order release kinetics, the plot of percentage drug release vs time will give a straight line with a slope of k₀ and intercept at zero.

First order kinetics

It describes the system in which the drug release rate dependent of its concentration.

Log Q_t = log Q₀ + k_t / 2.303

Where,

Q_t = amount of drug dissolved in time t

Q₀= initial amount of the drug in the solution

K_t= is the first order release constant

If the drug release obeys the first order drug release kinetics, then the plot of log percentage  drug remaining to be released vs time, shown a straight line with a slope of k_t/ 2.303 and an intercept at t=0 of log Q_0.

Higuchi model

It defines the fraction of drug release from the matrix is proportional to square root of time.

Mt / M?= kHt ^½

Where,

Mt/M? = cumulative amount, if drug release from at time t and infinite time

kH = Higuchi dissolution constant and reflection formulation characteristics

k’ is the release constant, t’ is the release time

If the drug release obeys higuchi model, plot of cumulative percentage drug release vs t ^½ will be straight line with the slop of kH.

Korsmeyer-peppas model

The power law describes the drug released from the polymeric system in which the release deviates from the fickian diffusion, which is expressed in following equation,

Log [Mt - M?] = log k + n log t

Where,

Mt-M? = cumulative amount of drug release at the time t and infinite time

k = constant incorporating structure and geometrical characteristic of CR device

n = diffusion release exponent indicative of mechanism of drug release for the drug dissolution.

A plot of log ?Mt-M?? (log   drug release) vs log time (log t) will be linear with slope of n and intercept gives the value of log k. antilog of k gives the value of k.

Swelling study

The extent swelling study is measured in terms of percentage weight gain of MCGs. The optimized formulation was determined in 900ml of 0.1 N Hcl solution (pH 1.2), at 37⁰c ±0.5⁰c. and the swelled MCGs are weighted time respectively 1 to 12 hrs, the excess of fluid was removed by using absorbing paper, the MCGs were weighted and the swelling index can be calculating by using the formula

SI = Mt – M0 × 100

Where,

            SI = swelling index

            M_t = weight of MCG at time t

            M₀ = weight of MCG at time 0

FT-IR studies

Interaction between the drug and polymer was studied by IR spectroscopy using the FT-IR spectrometer (460 plus, jasco-Japan) with diffuse reflectance principle.  By Potassium bromide pellet technique,   sample is triturated in glass motor and finally placed in the sample holder. The spectrum was scanned over the frequency range of 4000-400cm^-1.

Stability studies

Stability studies were carried out at 40⁰c ± 2 ⁰c / 75 of RH ± 5 RH for 30 days, for the selected formulation. The stability studies were done for formulation. These formulations were selected depending upon the in vitro drug release study of both drugs from both layers of the MCGs. The formulations were subjected to stability study.

       
           
       
Table No, 5. Dissolution Condition For The Formulation Trails

Preformulation studies

Melting point determination           

The melting point of pure metformin was found to be 133⁰c – 139⁰c.which was closer to the melting point of metformin.

The melting point of pure Glimepiride was found to be 94⁰c –98 ⁰c. This was closer to the melting point of Glimepiride.

Calibration curve

Standard graph of Metformin HCL

Weigh the Metformin HCL standard and transfer about 100 mg into a 100 ml volumetric flask. After adding roughly 60 ml of methanol and sonicating for 20 minutes, add enough methanol to make 100 ml of volume. A working solution is created by taking 1 ml of the stock solution and diluting it with 10 ml of methanol. At 233 nm, the absorbance was measured when 2,4,6,8, and 10 µg/ml were produced from the stock solution.

       
           
       
Table No, 6. Data Calibration Curve of Metformin

Standard graph of Glimepiride in 7.4 pH buffer

Preparation of standard stock solution Standard solution of Glimepiride was prepared by transferring accurately weighed 10 mg of drug into a 100 ml volumetric flask and the volume was made up to 100 ml using chloroform as a solvent to get the concentration of 100µg/ml.

Preparation of calibration curve

From the standard stock solution fresh aliquots were pipette out and suitably diluted with chloroform to get final concentration in the range of 5-30 µg/ml. The solutions were scanned under 200-400 nm wave length range and a sharp peak was obtained at 249 nm (Figure 1). Calibration curve was plotted by taking absorbance on y axis and concentration of solution on x-axis (Figure 2). The method was applied for known sample solution and was found to be satisfactory for analysis of MCG dosage forms.

       
           
       
Table No, 7. Data For Calibration Curve of Glimepiride

       
           
       
Figure No, 5. Calibration Curve of Glimepiride

Preparation of Metformin Hydrochloride - Solid Dispersion

       
           
       
Table No, 9. Evaluation of Pre Compression Solid Dispersion of API – II (F1-F4)

       
           
       
Table No, 10. Physical Compatibility Study

Formulation of Medicated Chewing Gum

Medicated chewing gum was prepared by using natural gum base wheat prolamin, calcium carbonate (Texture imparting agent), glycerin (Plasticizer), sodium saccharin (Sweetener), polyvinyl acetate (To increase the elasticity of the gum), and peppermint oil (Flavor).  

       
           
       
    Figure No, 6. Formulation of Medicated Chewing Gum

Based on the trial and error of batches, the concentration range of gum base, calcium carbonate and polyvinyl acetate was selected. The best possible levels obtained for gum base and calcium carbonate were 450 to 550 mg and 70 to 90 mg, respectively. Hard solid or sticky gum mass was formed, if deviated these ranges. Accurately weighed quantities of gum base, calcium carbonate, and saccharin were mixed properly in mortar. The polyvinyl acetate was dissolved in small quantity of ethanol and mixed in above excipients. Then glycerin and peppermint oil were added. The mixture was triturated until the solid mass was formed. Thin and wide ribbon were made out of this mass and cut in the desired size.

Post-Compression Parameter of Medicated Chewing Gum

Physical parameters

The post-compression parameters were performed in the formulated MCG and the results were summarized below. All the formulation complies with the standard limits. From this resulted data formulated MCG have a hardness range of 4.9-5.6 respectively. The Hardness of the MCG depends on the ratio of polymers and excipients used.  The friability of each formulation is below. This complies with in the standard limits.

       
           
       
Table No, 11. Post Compression Parameter of Medicated Chewing Gum

The swelling studies were performed in the formulated MCG (F1-F4) and the results were summarized below. The formulations (F1-F4) which have the higher swelling index results in minimizing the time of drug release from the formulated MCG and the formulation F1& F2 have

less swelling index which released the drug in unpredictable ratio. Formulations F3 & F4 have similar range of swelling index. Result was depicted in the table 12.

       
           
       
Table No, 12. Swelling Index (%)

       
           
       
Table No, 13. Comparison of In-Vitro Dissolution Profiles of all Formulations (API-I) % Drug Release

       
           
       
Figure No, 7. API - I % Drug Release  

       
           
       
Figure No, 8. API - II % Drug Release

       
           
       
Table No, 14. Comparison of In-Vitro Dissolution Profiles of all Formulations(API-II) % Drug Release

In-vitro dissolution drug release data discussion

The drug polymer ratio 1.4: 0.6 (F1) shows the drug release (API I - 99, API II - 64) at the end of 40 minutes the concentration of wheat prolamin and high concentration of PVA. Which shows the minimal drug release rate of API II from the MCG. The drug-polymer ratio 1.6: 0.4 (F2) shows the drug release (API I - 97.9, API II - 71.17) at the end of 40 minutes the high concentration of wheat prolamin and high concentration of PVA. Which shows the less drug release API I and minimal drug release rate of API II from the MCG. This less amount of drug release from the formulation due to the combination of two polymer ratios. The drug-polymer ratio 1.8:0.2 (F3) shows the drug release (API I - 98.5, API II - 98.65) at the end of 40 minutes the optimized concentration of wheat prolamin and PVA. Which shows the optimized combination of the formulation was release the drug in a controlled manner. The drug-polymer ratio 2.0: 0.05 (F4) shows the drug release (API I - 72.54, API II - 78.75) at the end of 40 minutes the higher concentration of wheat prolamins and very low concentration of PVA. This ratio of polymers reduced the concentration of drug release from the formulation. From the data observed with in vitro drug release the optimized formulation of F3 polymer ratio releases the drug from the formulation in a controlled manner and the maximum amount of drug released from the matrix in the course of duration.

Mathematical analysis of in-vitro release data

The in-vitro data is applied in the various kinetic models to predict the drug release mechanism. The slope values and the regression coefficient are summarized in table 15. The correlation coefficient is in the range of 0.986 – 0.996. It was found that the drug release data of the formulation batches are a good fit to the zero-order and the Korsmeyer Peppas equation.

       
           
       
Table No, 15. Mathematical Analysis of In-Vitro Release Data

       
           
       
Table No, 16. Regression Coefficient and Slope Values of the Kinetic Models

       
           
       
Figure No, 9. Slope Values of the Kinetic Models

Fourier transformers infrared spectroscopy (FT-IR)

Metformin illustrated the characteristic peak Metformin has strong absorption bands at 1562, 1573, and 1634 cm-1 due to the stretching of C=N vibrations. The FTIR spectra of the solid dispersions show a reduction in the intensity of the characteristic metformin bands at 1626 cm-1, 3294 cm-1 and 3369 cm-1, which may be due to weak hydrogen bonding between the drug and polymer presence of hydroxyl group, carbonyl group, keto group, ether group. Bands in the FTIR spectra of metformin: 1205, 1160, 1151, 1142, 1080, 1061 and 1035 cm-1: C=N stretching vibrations 600–400 cm-1: CNC deformation vibrations 571, 541, 517, 482, 464, 446, and 420 cm-1: CNC deformation.

Glimepiride shows sharp peaks at 3369 cm-1 and 3288 cm-1 due to N-H stretching, 1707 cm-1 and 1674 cm-1 due to carbonyl group, 1345 cm-1 showing C-N stretching vibration, and 1153 cm-1 showing S=O. stretching vibration. FTIR stretching of C=O. group is at 1656-1715cm-1 and stretching of C-H bond at 2922 cm-1. The peaks slightly shift in different batches at 2954, 2873, 2837, 2886, 2939, and 2933 cm-1 respectively. FTIR spectra of PVA show absorption peaks from the PVA, including: O-H stretching: At about 3300 cm?1, C-O stretching: At around 1085 cm?1, Asymmetric CH2 stretching: At around 2910 cm?1. The spectra of crystalline and amorphous lactose contain bands at 3600-3200 cm ?1, 1650 cm ?1 and 1200-1070 cm ?1. The main IR spectral shifts from 3371 to 3,347 cm?1 and 1693 to 1682 cm?1, as well as from 3094 to 3136 cm?1 and 1718 to 1735 cm?1 for Saccharin suggested that the O single bond H and N single bond H groups in both chemical structures were taken part in a hydrogen bonding.

       
           
       
Figure No, 10. FTIR Interpretation Data

       
           
       
Table No, 17. FTIR Interpretation of Pure Drug and Compounds

Stability studies

Stability studies were done for the optimized formulation (F4) at 40⁰c ± 2⁰c /, 75 of RH ± 5 RH as per the standard guidelines and the results are summarized in the table 18

       
           
       
Table No, 18. Stability Studies

Stability studies were done for the optimized formulation (F3) at 40⁰c ± 2⁰c, 75 of RH ± 5 RH as per the standard guidelines and there is no significant change in the drug content and the drug release from the optimized formulation (F3).

CONCLUSION

The Medicated chewing gum containing anti-diabetic drug is formulated successively by using hydrophilic swellable polymer. The formulations were validated in terms of thickness, hardness, weight variation and friability, drug content, swelling index, in-vitro drug release study, stability study and FT-IR studies. All the formulations were shown fairly acceptable data for all the parameters evaluated for the drug polymer ratio 1.4: 0.6 (F1) shows the drug release (API I - 99, API II - 64) at the end of 40 minutes the concentration of wheat prolamin and high concentration of PVA. Which shows the minimal drug release rate of API II from the MCG. The drug-polymer ratio 1.6: 0.4 (F2) shows the drug release (API I - 97.9, API II - 71.17) at the end of 40 minutes the high concentration of wheat prolamin and high concentration of PVA. Which shows the less drug release API I and minimal drug release rate of API II from the MCG. This less amount of drug release from the formulation due to the combination of two polymer ratios. The drug-polymer ratio 1.8:0.2 (F3) shows the drug release (API I - 98.5, API II - 98.65) at the end of 40 minutes the optimized concentration of wheat prolamin and PVA. Which shows the optimized combination of the formulation was release the drug in a controlled manner. The drug-polymer ratio 2.0:0.05 (F4) shows the drug release (API I - 72.54, API II - 78.75) at the end of 40 minutes the higher concentration of wheat prolamins and very low concentration of PVA. This ratio of polymers reduced the concentration of drug release from the formulation.
       
           
       
The formulation F1, F2 formulated by using the less quantity of polymer ratio, shows high drug release profile within the duration. The formulation F4 shows less drug release profile in the duration of time, hence reaching the maximum release of drug with maximizing the time, with this the chance of patient complains will decreases. In the optimized polymer ratio in F3 will shows better drug release profile in the duration of time. From the data observed with in vitro drug release the optimized formulation of F3 polymer ratio releases the drug from the formulation in a controlled manner and the maximum amount of drug released from the matrix in the course of duration. From the various kinetic model for Medicated chewing gum, it can be concluded that the F3 showing Korsmeyer Peppas kinetic as the plot of the model shown higher regression (R²=0.995). The release mechanism can be concluded that diffusion controlled mechanism. From the results of stability data provided, it can be concluded that the formulation was stable at the condition 40⁰c /75   RH for one month. All the parameters like drug content of the MCG and consistency in dissolution studies even after simulating extreme consistency during their storage. From this above discussion it is concluded the MCG containing anti diabetic drug, good means of promising therapy which achieving higher patient compliance.