Hygroscopicities of 3-Aminopyridine (3AP) and Fatty Acid Complexes (FA-3AP), and the Release of 3AP from FA-3AP

Abstract

The hygroscopicity of 3-aminopyridine (3AP) and fatty acids complexes (FA-3AP) was measured under various levels of humidity at 30°C, where the carbon number (n) of the constituent fatty acid (FA) was 14-18. The release behavior of 3AP from FA-3AP was then examined in a JP XII dissolution test apparatus using JP XII disintegration test medium No. 1 (pH 1.2) at 37°C.3AP was extremely hygroscopic : 3AP was completely deliquesced during storage at relative humidity levels above 80%.In contrast, FA-3AP did not absorb moisture even at 100% relative humidity during at least one month of storage.3AP was released speedily from FA-3AP in the aqueous test medium. The values of T₅₀ and T₈₀, which represent the time required for 50% and 80% of 3AP to release, were 1-3 and 2-6min, respectively for five different types of FA-3AP. The values of T₅₀ or T₈₀ for FA-3AP formed with odd-numbered FA were larger than those for FA-3AP formed with even-numbered FA, which has an alkyl chain lengh one carbon number longer, though the values of T₅₀ or T₈₀ increased rather regularly with an increase in alkyl chain lengh for only even-numbered or odd-numbered FA. This was the same tendency as previously observed for the FA-nicotinamide complex.