Stability of captopril in some aqueous systems

Area of Science:

• Pharmaceutical Sciences
• Analytical Chemistry

Background:

• Captopril is a widely used angiotensin-converting enzyme inhibitor.
• Assessing the stability of oral liquid dosage forms is crucial for ensuring therapeutic efficacy.
• Captopril is known to be sensitive to oxidative degradation.

Purpose of the Study:

• To develop and validate a stability-indicating high-performance liquid chromatographic (HPLC) method for quantifying captopril.
• To evaluate the stability of captopril in various oral liquid dosage forms.
• To compare the stability of captopril in formulations prepared from tablets versus powder, using water or syrup as vehicles.

Main Methods:

• Development and validation of a stability-indicating HPLC method for captopril quantification.
• Preparation of oral liquid dosage forms using commercially available captopril tablets and powder.
• Stability studies of captopril formulations stored under specific conditions, with analysis by HPLC.
• Kinetic analysis of captopril decomposition.

Main Results:

• The developed HPLC method accurately quantifies captopril and its degradation products.
• Captopril formulations in water were significantly more stable than those in syrup.
• Formulations prepared from powder in water showed enhanced stability compared to those prepared from tablets in water.
• Decomposition kinetics varied; first-order kinetics were observed in syrup but not consistently in water, potentially due to oxidation.

Conclusions:

• The choice of vehicle (water vs. syrup) significantly impacts captopril stability in oral liquid dosage forms.
• Formulation from powder in water offers superior stability for captopril compared to using tablets.
• Oxidation is a critical factor affecting captopril stability, necessitating careful formulation and storage considerations.