[Evaluation of correlation between gelatin crosslinking indicators and influence factors].
OBJECTIVE
To evaluate the correlation between the swelling equilibrium quantity (Seq), dissolution rate and amino group content which were used to estimate the degree of gelatin crosslinking, and the factors which influence the crosslinking, and to investigate the crosslinking mechanism of delayed dissolution of soft capsules.


METHODS
The swelling equilibrium quantity, dissolution rate and amino group content of formaldehyde-crosslinked capsule shells were determined. Gelatin structure was analyzed by means of DSC.


RESULTS
A good lineal relativity was found between the swelling equilibrium quantity, dissolution rate and amino group content (r = 0.9953-0.9985). The Seq of capsule shells was influenced by high temperature, lighting and some additives. Glycine and sodium pyrosulfite might retard the decrease of Seq of capsule shells.


CONCLUSIONS
The swelling equilibrium quantity, dissolution rate and amino group content exhibited the same rule in gelatin crosslinking extent. High temperature, lighting and some additives might induce gelatin crosslinking. Antioxidant such as glycine and sodium pyrosulfite might retard the crosslinking.
Liu
Jian-ping
JP
Pharmaceutical Institute, China Pharmaceutical University, Nanjing 210009, China. liujianpingljp@hotmail.com
Ma
Xu
X
Zhu
Jia-bi
JB
D000596:Amino Acids / Q000032:analysis; D002214:Capsules; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods; D004355:Drug Stability; D005557:Formaldehyde / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry*; D005998:Glycine; D006813:Humidity; D008029:Lighting; D010592:Pharmaceutic Aids / Q000737:chemistry; D012995:Solubility; D013696:Temperature
D000596:Amino Acids; D002214:Capsules; D003432:Cross-Linking Reagents; D010592:Pharmaceutic Aids; D005557:Formaldehyde; D005780:Gelatin; D005998:Glycine