title: [Kinetic study on the degradation of penicillin potassium at different temperature and relative humidity].
abstract: OBJECTIVE
  To perform a kinetic analysis and formulation of the degradation of penicillin potassium in the solid phase at different temperature and relative humidity.
  
  
  METHODS
  Penicillin potassium was incubated in a temperature-and-humidity-controlled oven at different temperature and relative humidity, and was determined by HPLC at suitable time intervals during the incubation.
  
  
  RESULTS
  The reaction rate was expressed as -dc/dt=k(c0-c+B), where c is the residual concentration, k degradation rate constant, c0 original concentration and B a constant related to original concentration of degradant. Degradation curves were fitted with c=c0-Bexp (kt)+B. The k was expressed as k=Aexp(-Ea/RT)exp(mHr), where active energy E. is 77.26 kJ/mol and constant m 0.1159.
  
  
  CONCLUSIONS
  The degradation of penicillin potassium could be expressed with c=c0-Bexp [Aexp (-Ea/RT)exp (mHr)t]+B.
authors.affiliation: Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.forename: Xian-Cheng
authors.initials: XC
authors.lastname: Zhan
authors.forename: Lin-Li
authors.initials: LL
authors.lastname: Li
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Ying
authors.forename: Ning
authors.initials: N
authors.lastname: He
mesh_terms: D004355:Drug Stability; D006813:Humidity; D007700:Kinetics; D008433:Mathematics; D010400:Penicillin G / Q000737:chemistry*; D013696:Temperature
chemical_list: D010400:Penicillin G