HYGROSCOPICITIES OF 3-AMINOPYRIDINE (3AP) AND FATTY-ACID COMPLEXES (FA-3AP), AND THE RELEASE OF 3AP FROM FA-3AP

The hygroscopicity of 3-aminopyridine (3AP) and fatty acids complexes (FA-3AP) was measured under various levels of humidity at 30-degrees-C , where the carbon number (n) of the constituent fatty acid (FA) was 1 4-18. The release behavior of 3AP from FA-3AP was then examined in a J P XII dissolution test apparatus using JP XII disintegration test medi um No. 1 (pH 1.2) at 37-degrees-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% re lative humidity during at least one month of storage. 3AP was released speedily from FA-3AP in the aqueous test medium. The values of T50 an d T80, which represent the time required for 50% and 80% of 3AP to rel ease, were 1-3 and 2-6 min, respectively for five different types of F A-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 length one carbon number longer, though the values of T50 or T80 increased rather regularly with an increase in alkyl ch ain length for only even-numbered or odd-numbered FA. This was the sam e tendency as previously observed for the FA-nicotinamide complex.