Abstract
The stability of metoprolol and carvedilol in extemporaneously prepared oral liquids was studied. An aqueous liquid formulation of each drug was prepared by reconstituting the powder from triturated tablets with a mixture of deionized water and 70% sorbitol solution. The expected metoprolol concentration was 1.25 mg/mL and for carvedilol was 0.625 mg/mL. Polyethylene terephthalate (PET) plastic bottles containing metoprolol and carvedilol liquids were stored at ambient room temperature (22° to 26°C, and in the refrigerator (4° to 8C). After storage periods of 1, 2, 4, and 8 weeks, these samples were analyzed in triplicate for the respective drug concentrations by high-performance liquid chromatography (HPLC). The concentration of each drug was found to be within the acceptable limit (± 10% of the initial concentration) in all test samples, which indicated that metoprolol and carvedilol liquids were stable at room temperature and refrigerated for up to 8 weeks. However, there were signs of possible decomposition in metoprolol oral liquid after 8 weeks of storage at room temperature. Additionally, our study findings revealed that there was no microbial growth in either drug liquid after a refrigerated storage period of 2 weeks.
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