Pure Pharmaceutical sample of Diltiazem was obtained from sun Pharma Technologies Pvt Ltd, Diltiazem Tablet (DILZEM-30, Conventional release) containing Diltiazem Hydrochloride (30mg, Torrent Pharmaceuticals LTD) were procured from local market of Berhampur.

Hydrogen peroxide, chloroform, NAOH, Methanol from Loba chemicals. Pvt. Ltd., India, Water from Royal college of pharmacy and health sciences laboratory, India

HPLC Shimadzu Japan Pump LC 20-AT, Detector SPD20A, syringe Hemilton Rheodyne- 25µl, column Shimadzu Japan (250×4.6mm, packed with5µ), UV-Vis Spectroscopy Shimadzu, Japan UV1700, Digital electronic balance Shimadzu Japan xp205, ph. meter Thermos fisher scientific USA Orion 5star, ultrasonic bath sonicator Pci Mumbai Rk102 CH Liter3,0, Hot air oven York scientific industry pvt. ltd., India, FTIR Perkin Elmer (spectrumV5.3.1) Different scanning calorimetry (DSC-60, Shimadzu, Japan)

Using a reverse phase octadecyl bonded silica gel C18 column, the solvent use for mobile phase was methanol with water (90:10) was equilibrated at a flowing capacity of 1ml/min. The eluent was detected at 236nm for Diltiazem. A 25µl sample was inserted with a fixed loop and the run time was 10min. This procedure was repeated daily for six days, and the outcomes were expressed as standard deviation and %RSD. ²⁵

To prepare the mobile phase of total 300 ml, HPLC-grade methanol mixed with Mili-Q Water solution to a (90:10) v/v proportion respectively. Then the sonication of mobile phase was  occurred for 10min. In a 10ml volumetric flask the powder drug was dissolve in the mobile phase and volume make up to the mark. ²⁵

From the prepared stock solution 1ml was taken and 10ml volume adjusted by adding mobile phase to get 100ppm concentration. The standard stock solution of 1000ppm of Diltiazem was prepared by dissolving 10mg of pure powder drug in mobile phase, in10mlvolumetric flask and the volume was made up to the mark. From the prepared stock solution 1ml taken and volume adjusted to 10 ml by adding mobile phase to get 100ppm concentration.

The 1000ppm conc. of standard solution was prepared by taking 1ml of solution from the mobile phase and dissolved with 10mg of pure powder drug of diltiazem. then the volume makes of up to the mark of 10ml volumetric flask. 1ml was taken from the above stock solution and volume makeup up to the mark of 10ml volumetric flask by adding the mobile phase then we got 100ppm concentration.

The aliquots amount of stock solution of drug was taken in a 10ml volumetric flask and the volume was made up to the label by adding the mobile phase in a serial manner of 10-50µg/ml. Chromatograph was made under this above concentration by injecting the 25µl sample. Then the drug evaluation carried out and the area of peak was recorded at 236nm. The calibration curve was Plotted by taking the peak area on the x-axis and the concentration on the y-axis.

Weighed accurately 6 tablets were used to calculate the average weight. After crushing, tablet powder equivalent to 180mg of diltiazem and 25mg of that was transfer to a 250ml conical flask. About 100ml methanol was added and sonicate for 30min, with continuous shaking (maintaining the temperature of sonication below 20⁰C). The volume was made up to the mark with diluent and mixed. The solution was filtered through a 0.45µm PVDF filter. The filtrate was collected, with the top few millimetres discarded. Prepared 10ppm of that solution and again added in 100ml of diluents to obtain a typical chromatogram.

The FTIR spectra of Diltiazem, carrier, and their binary solid dispersions (Spectrum BX) were captured by a Perkin Elmer FTIR spectrophotometer. Sample was mixed with spectroscopic grade potassium bromide and compressed into discs using a hydraulic press before being scanned from 4000 to 500 cm^-1. Data analysis software from Perkin Elmer was employed. (spectrum V5.3.1).

The thermal behaviour of Diltiazem was examined using DSC. To obtain the spectra of DSC the instrument used was DSC-4000, PERKIN ELMER, all the samples weight 5mg and placed in an aluminium pan then to cover it place an aluminium lid, the scanning takes place at a temp rate of 40⁰C/min from 30⁰C to 300⁰C.

A minimal volume of methanol was added to a 10ml volumetric flask containing the precisely weighted 10mg equivalent drug. After that, add liquid to make up the volume and maintain the temperature at 700⁰C. The solutions were made at various intervals of time, and the HPLC equipment was filled with 10 ppm of the sample solutions.

The accurately weighed 10mg equivalent drug was ingested in a 10ml volumetric flask and dissolved in minimum volume of methanol. Then the volume was made up to the mark by using 1N HCL and kept at 700⁰C. The solutions were prepared at different time interval and 10ppm of the sample solutions were inserted into the HPLC apparatus.

In a 10ml volumetric flask, the precisely weighted 10mg equivalent drug was taken in and dissolved in the smallest amount of methanol. The volume was then increased to the required level using 1N NaOH and maintained at 700⁰C.A 10ppm sample solution was added to the HPLC equipment after the solution was made at various interval.

In a 10 ml volumetric flask, the precisely weighted 10mg equivalent drug was taken in and dissolved in the smallest amount of methanol. After that make volume up to the mark by using 6%w/v H2O2 and kept at 700⁰C. The solutions were prepared at different time interval and 10ppm of the sample’s solution were loaded into the HPLC Apparatus.

In three different, clean petridishes,100mg 100mg of pure drugs were taken. The drugs were then dried at 700⁰C, and sampling was done every 10days, 20days, 30days. Drug solutions were produced, and the HPLC apparatus was loaded with 10ppm of the sample solutions.

Solubility: Solubility of Diltiazem was performed using various solvents and the results are shown below.

As per solubility parameter of diltiazem, the different mobile phase system individually and in combination ratios with different rate of flow and pH were tried to get a symmetric and sharp peak. Finally, Methanol:Water in the ratio (90:10) was found to be ideal mobile phase system for the drug.

A calibration curve was plot by using the concentration on X-axis and peak area on Y-axis.

From the calibration curve it was found that it shows linearity in the range of 10-60µg/ml with regression coefficient 0.999.

For the determination of % of purity, we can calculate by formula: y = mx + c

we got y value which is the area for 20ppm of drug sample from the Table 18, and we have to calculate x 9 conc. of drug)

X = y - c/m

By put the values we get, X = y - 2.3901/35.313

= 854.582-2.3901/35.313

= 852.191/35.313

=24.132

For 25ppm concentration of drug is and calculate for 100ppm

= 24.132/25×100

= 96.52%

So, we concluded % purity of Diltiazem (marketed drug) is 96.52%.

According to the protocol the sample were withdrawn. 50μg/ml solution were prepared and loaded for analysis after drawn from the Sample. The result it indicates that, there was no change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

After 10 days, the result it indicates that, there was no change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

According to the protocol the samples were withdrawn. 50μg/ml of prepared solution were subjected for analysis after drawn from the sample. The result it indicates that, there was no change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

After 10 days, the result it indicates that, there was no change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

According to the protocol the samples were withdrawn. 50μg/ml of prepared solution were subjected for analysis after drawn from the sample. The result it indicates that, there was no change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

After 10 days, the result it indicates that, there was change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

According to the mentioned protocol in experimental part, samples were withdrawn. From 50μg/ml of prepared solution were subjected for analysis after drawn from the sample. There are no degradation takes place after 7 days that indicated by the representative chromatogram. The extra peak is for H₂O_2.

According to the protocol the Samples were withdrawn according to the protocol. 50μg/ml solutions were prepared and loaded for analysis after drawn from the sample. The result it indicates that, there was no change in peak area, peak height, and retention time of drug peak in the above condition. It indicates that no degradation takes place in this condition.

There is no degradation after 10 days at 70⁰C. The resulted Peak also reveals that the drug can be analysed in presence of their degradants.

Differential Scanning Calorimetry (DSC) By analysing the thermal behaviour of the preparation, differential scanning calorimetry (DSC) was utilized to assess the melting point, crystallinity, breakdown, and drug-excipient interaction. By maintaining a heating rate of 1⁰C/min, the DSC verified the presence of the medication Diltiazem showed a pronounced endothermic peak with an onset temperature of 215.75⁰C and a peak temperature of 225.26⁰C, which is the same as its melting point.

Fourier-transform infrared spectroscopy (FTIR) The FTIR spectra of Diltiazem and their solid dispersions were captured. using FTIR spectrophotometer. Samples were mixed with spectroscopic grade potassium bromide and compressed into discs using a hydraulic press before being scanned from 4000 to 500 cm^-1. Data analysis software from Perkin Elmer was employed.