A study of the chemical and biological stability of vasoactive intestinal peptide

Abstract

Context: Vasoactive intestinal peptide (VIP) is a linear cationic neuropeptide composed of 28 amino acids. It belongs to the glucagon/secretin family. The biological functions of VIP are relatively broad, but it has not been well studied in the field of pharmaceutics. Especially in the selection of the way of VIP administration and the pharmaceutical formulation, the theory basis was deficient appreciably.

Objective: To provide the theory basis for the pharmaceutical development of VIP, the chemical and biological stability of VIP was studied. Materials and methods: The stability of VIP in different pH values, ionic strength, temperature, artificial gastric fluid and artificial intestinal fluid was investigated, and the concentration of VIP was calculated by HPLC method.

Results: The stability of VIP was pH-dependent. VIP was stable in acid and neutral solution, and almost didn’t degrade during pH ≤ 7 solution. However, it was instability in basic solution and degraded completely at 30 min in pH 13 solution. Ionic strength did not affect its stability. VIP was stable in freezing conditions but it degraded at low concentration in cold storage. Furthermore, VIP degraded so quickly in artificial gastric fluid and artificial intestinal fluid that it can’t be detected at 0 min.

Discussion and conclusion: the chemical and biological characteristic of VIP was unstable, so it isn’t suitable for oral administration.

Keywords::

• Vasoactive intestinal peptide
• stability
• artificial gastric fluid
• artificial intestinal fluid
• oral administration

Acknowledgments

The authors gratefully acknowledge the help of Mr. Jianxu SUN and other companions in our research team.

Declaration of interest

This work was supported by the National Key Technologies Research and Development Program for New Drugs of China (No. 2011ZX09301-003) and the Natural Science Foundation of Hebei Province (No.C2009001066).