Lab Report: Microwave Induced Solid Dispersions of Carvedilol

Abstract

The objective of this study was to enhance the solubility of Carvedilol (CDL) by creating solid dispersions (SD) in varying proportions (1:1, 1:2, 1:4, and 1:6) of CDL and Poloxamers (Poloxamer-188 and Poloxamer-338) using a unique microwave fusion technique. These SDs were subsequently compressed into tablets using an 8-station tablet compression machine. Compatibility between CDL and Poloxamer carriers was assessed using differential scanning calorimetry (DSC) and Fourier Transform Infrared (FTIR) Spectroscopy. The prepared SD tablets underwent post-formulation testing. The 1:6 ratio of drug to carrier exhibited improved solubility and dissolution.

DSC and FTIR analyses confirmed the compatibility of CDL with the Poloxamer carriers. Release kinetics of the formulations followed first-order kinetics. These evaluations indicated favorable physicochemical characteristics, particularly enhanced solubility. Among the formulations, solid dispersions with a CVL: Poloxamer carrier ratio of 1:6 demonstrated the most significant improvements in solubility and drug release characteristics.

Keywords

Carvedilol, tablets, polymer, solubility, characterization

Introduction

Discovering and developing new chemical molecules to improve drug solubility is often a costly and time-consuming endeavor.

Get quality help now

Writer Lyla

Verified writer

Proficient in: Chemistry

5 (876)

“ Have been using her for a while and please believe when I tell you, she never fail. Thanks Writer Lyla you are indeed awesome ”

+84 relevant experts are online

Hire writer

Researchers in the pharmaceutical industry frequently experiment with various methods to enhance drug solubility while minimizing costs. Among these approaches, solid dispersions (SDs) offer a cost-effective and straightforward solution.

Carvedilol (CVL) is an antihypertensive medication prescribed for conditions such as congestive cardiac failure and left ventricular malfunction. CVL belongs to Biopharmaceutics Classification System (BCS) Class-II, characterized by low water solubility and a bioavailability of less than 30%.

Traditional methods of preparing SDs by melting can lead to undesirable variations in polymer properties due to inconsistent heating. To address this issue, microwave melting (MWM) has emerged as an innovative technique, utilizing electromagnetic irradiation for controlled heating.

In this study, we explore the potential of MWM in preparing SDs, with CVL as the model drug.

Mouth dissolving tablets (MDTs) provide a practical solution for ensuring drug administration even in the absence of water. Additionally, this study provides valuable insights for researchers seeking to identify the optimal Poloxamer carrier (specifically Poloxamer-188 and Poloxamer-338) to enhance CVL solubility.

Materials and Methods

Materials

Drug-Excipient Compatibility Studies

Drug compatibility with the selected carriers was evaluated using Differential Scanning Calorimetry (DSC) and Fourier-transform Infrared (FTIR) spectroscopy.

Differential Scanning Calorimetry (DSC)

A 10 mg blend of CVL and Poloxamer (1:1) was analyzed using a DSC instrument, heating at a rate of 10°C/min from 50°C to 250°C (DSC-50, Shimadzu, Japan).

Fourier-Transform Infrared (FTIR) Spectroscopy

Interactions between CVL and Poloxamers were examined using FTIR spectroscopy (Bruker) over a range of 4000-400 cm^-1.

Preparation of Solid Dispersions

The SDs were prepared using the microwave melting (MWM) technique. Different ratios of CVL and Poloxamer carriers were subjected to microwaves for 5 minutes at 560 W in a scientific microwave oven (CATA-2R, Catalytic Systems, India). Subsequently, the samples were allowed to solidify at room temperature, collected, and placed in a glass desiccator for 24 hours. Afterward, the SDs were powdered in a mortar and pestle and sifted through an 80# sieve.

Table 2. Carvedilol: Carrier Ratios in Various Formulations

Evaluation of Solid Dispersions

The following parameters were assessed for CVL-SD formulations:

Flow Properties

The designed SDs were evaluated for micromeritic properties, including the angle of repose, true and tapped densities, Carr's Index, and Hausner ratio. The results of powdered blend flow properties are summarized in Figure 1.

Yield

The percentage recovery of CVL SDs was determined after complete moisture removal using the following formula:

% Yield = (Actual weight of the solid dispersions) / (Total weight of drug and excipients) x 100

Compression of Solid Dispersions as Tablets

The SDs equivalent to CVL were directly compressed into tablets after mixing with various ingredients (as shown in Table 3) using an 8-station tablet compression machine (Karnavati Engineering, Ahmedabad, India).

Table 3. Formulation of Tablets Containing Solid Dispersions

Evaluation of Solid Dispersions Tablets

The compressed SDs tablets were evaluated for the following parameters:

Morphological Characteristics

The prepared CVL SDs tablets were inspected for uniform size and shape.

Thickness

The CVL SDs tablets were assessed for uniform thickness using vernier calipers (Qumos Enterprises, Mumbai, India).

Hardness

The tablet hardness, measured using a Monsanto tablet hardness tester (Vinsyst Technologies, Mumbai), represented the force required to break the tablets. Three tablets were individually tested to determine the mean value.

Uniformity in Weight

Twenty tablets randomly selected from each batch were individually weighed using an electronic digital balance (Citizen, CY-104, Mumbai, India). The average weight was calculated and compared with the individual tablet weights. The percentage weight difference was calculated and checked against IP specifications (Limit ± 7.5% of average weight).

Friability

The loss on friability of the powdered blend is summarized in Figure 2.

Uniformity of Drug Content

Drug content was determined by UV spectrophotometer at 360 nm as per the procedure by Panwar et al. A weighed amount of SDs equivalent to 20 mg CVL was dissolved in a 100 ml volumetric flask, and volume was made up with methanol. The solution was filtered, and 1 ml of this solution was further diluted in a 10 ml volumetric flask and analyzed for absorbance at 360 nm using a UV-Visible spectrophotometer (Lab India, Mumbai). Content uniformity was determined using a CVL standard calibration graph.

Carvedilol Calibration Curve

The process of determining CVL concentration by UV spectrophotometer at 360 nm was standardized, and the drug was found to obey Beer-Lambert's law within the concentration range of 2-10 µg/mL.

Results and Discussion

The results of our study demonstrate the successful preparation of Carvedilol (CVL) solid dispersions (SDs) using a microwave-induced fusion technique with varying ratios of CVL and Poloxamers (Poloxamer-188 and Poloxamer-338). The key findings and discussions are summarized below:

Solubility and Dissolution

Our investigation revealed that the SD formulation with a CVL: Poloxamer carrier ratio of 1:6 exhibited significantly improved solubility and dissolution characteristics compared to other ratios. This finding suggests that this specific formulation can potentially enhance the bioavailability of CVL, addressing its poor solubility issue.

Compatibility Studies

Differential scanning calorimetry (DSC) and Fourier Transform Infrared (FTIR) spectroscopy confirmed the compatibility of CVL with the Poloxamer carriers used in our study. This is crucial as drug-polymer compatibility is essential to ensure the stability and effectiveness of the final product.

Release Kinetics

The release kinetics of the formulations followed a first-order release pattern. This indicates that the release of CVL from the SDs can be predictably controlled, which is a desirable characteristic for pharmaceutical formulations.

Overall, our results suggest that microwave-induced solid dispersions offer a promising approach to improve the solubility and dissolution rate of poorly water-soluble drugs like CVL. The choice of Poloxamer carrier and the drug-carrier ratio play a crucial role in determining the success of the formulation.

Conclusion

In conclusion, our study successfully prepared Carvedilol (CVL) solid dispersions (SDs) using a microwave-induced fusion technique. We found that the SD formulation with a CVL: Poloxamer carrier ratio of 1:6 demonstrated the most significant improvements in solubility and dissolution characteristics, potentially enhancing the bioavailability of CVL.

Compatibility studies using DSC and FTIR confirmed the suitability of the chosen Poloxamer carriers, ensuring the stability of the formulations. The release kinetics followed a first-order pattern, allowing for predictable drug release.

This study highlights the potential of microwave-induced SDs as a cost-effective and efficient method for improving the solubility of poorly water-soluble drugs. Further research and development in this area could lead to the development of more effective drug formulations with enhanced therapeutic outcomes.