Related Experiment Video
Updated: Aug 23, 2026

Standardized Measurement of Nasal Membrane Transepithelial Potential Difference (NPD)
Published on: September 13, 2018
Ionic interaction of amiloride and uridine 5'-triphosphate in nebulizer solutions
Ronald J Pettis1, Michael R Knowles, Kenneth N Olivier
1Becton Dickinson Technologies, 21 Davis Drive, PO Box 12016, RTP, North Carolina 27709, USA.
Abstract:
Combination therapy using nebulized amiloride hydrochloride and uridine-5'-triphosphate (UTP) trisodium salt aerosols has been investigated for the treatment of cystic fibrosis (CF). Amiloride in aqueous solution precipitates in the presence of UTP, reducing drug concentrations. Interactions between these drugs and NaCl in solution were studied using phase-solubility techniques monitored by UV spectrophotometry. Elemental analyses were employed for precipitate characterization. Amiloride solubility was reduced by more than 85% in saline. Amiloride solubility decreased with increasing UTP concentration, resulting in formation of a precipitated complex. The theoretical molar ratio of complexes range from 1-3 amiloride:1 UTP. At most concentrations only 3 amiloride:1 UTP complex was observed in precipitate. This is a reflection of low Ksp for the 3:1 complex of 2.92 x 10(-11) M4 compared with 2.09 x 10(-4) M2 for amiloride alone. Equilibration over excess bulk solid resulted in higher solubility estimates and different phase solubility diagrams than solubility studies utilizing precipitation technique. This may be explained by the absence of amiloride in the solid state and its impact on complex equilibria with UTP. The solubility suppressing effects of UTP and saline were largely additive. A number of ionic interactions increase complex solubility profile of amiloride hydrochloride in the presence of UTP and NaCl.
Related Concept Videos
Pore Transport and Ion-Pair Transport
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
Basicity of Heterocyclic Aromatic Amines
Drug Elimination by Renal Route: Tubular Reabsorption
Factors Affecting Solubility
Drug Elimination by Renal Route: Tubular Secretion
Colloidal precipitates

