Stability-indicating methods for the determination of disopyramide phosphate

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis

Background:

• Disopyramide phosphate is a critical pharmaceutical agent.
• Accurate quantification is essential for quality control and patient safety.
• Existing methods may face challenges with degradation products.

Purpose of the Study:

• To develop and validate novel analytical methods for disopyramide phosphate determination.
• To assess method specificity in the presence of degradation products.
• To compare the performance of developed methods with official standards.

Main Methods:

• Third-derivative spectrophotometry and first derivative of ratio spectra were employed.
• An ion-selective electrode (ISE) was fabricated using phosphotungstic acid.
• Quantitative densitometry using silica gel plates was performed.

Main Results:

• Spectrophotometric methods achieved high recovery (99.9-100.8%) in the 12.5-87.5 µg/mL range.
• The ISE method demonstrated a slope of 58.5 mV/decade with 99.9% recovery.
• Densitometry yielded 100.3% accuracy in the 0.25-2.5 µg/spot range.
• All methods showed high specificity for disopyramide phosphate against its degradation products.

Conclusions:

• The four developed methods are specific and accurate for disopyramide phosphate quantification.
• These methods are suitable for analyzing disopyramide phosphate in pharmaceutical formulations like Norpace capsules.
• No significant differences were observed when compared to the official method, indicating their reliability.