title: [A study on the degradation kinetics of nicotinamide powder].
abstract: The effect of temperature and humidity on the degradation of nicotinamide powder was studied below the critical relative humidity at temperatures 50-80 degrees C and relative humidities 50-80%. The rate equation of the degradation of nicotinamide under isothermal and constant humidity conditions is -dC/dt=k(Co-C)-1, where k is the apparent rate constant of degradation, Co and C are initial concentration and concentration at time t of nicotinamide, respectively. The relationship between the apparent rate constant of degradation and relative humidity RH is in K=a + m (RH), where a and m are constants. When RH are 50.35, 66.85, 75.33 and 80.35%, the apparent activation energies of degradation from Arrhenius equation are 219.94, 181.86, 168.99 and 153.89 kJ/mol, respectively. The rate equation the photodegradation of nicotinamide under room temperature is -dR/dt=K' (Ro-R)-1, where K' is the apparent rate constant of photodegradation, Ro and R are initial reflectance and reflectance at time t of nicotinamide, respectively.
authors.affiliation: Department of Physical Pharmacy, School of Pharmacy.
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: D
authors.initials: D
authors.lastname: Deng
authors.forename: B
authors.initials: B
authors.lastname: Ma
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: G
authors.initials: G
authors.lastname: Yin
mesh_terms: D006813:Humidity; D009536:Niacinamide / Q000737:chemistry*; D011208:Powders; D013696:Temperature
chemical_list: D011208:Powders; D009536:Niacinamide