Accelerated Stability Assessment of Extemporaneously Compounded Amiloride Nasal Spray

Amiloride is a U.S. Food and Drug Administration-approved diuretic agent used to treat hypertension and congestive heart failure. Recent human and animal studies have suggested that amiloride may also have a role in treating anxiety through its acid-sensing ion channel antagonism. Intranasal administration of amiloride nasal spray via an extemporaneously compounded preparation has the potential for rapid delivery to the site of action to achieve therapeutic outcomes in individual patients with anxiety disorders. However, these patient-specific preparations do not have the pre-formulation characterization, including chemical stability, that conventional manufactured dosage forms have. The objective of this study was to assess the estimated chemical stability of compounded amiloride nasal spray over 6 months and 12 months utilizing accelerated degradation with high heat and the Arrhenius equation. A stability-indicating highperformance liquid chromatography analytical method was employed at appropriate intervals over a 12-month period to reveal that amiloride remained chemically stable over the period tested and by extrapolation. Physical stability and compatibility with the preservative benzyl alcohol were also confirmed via visual inspection, pH monitoring, and measurement of turbidity.