Dosage forms exam 1 stability 3
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Chemical kinetics equations
Rate= +/ dC/dT Concentration over time
rate=k (a+b)[A][B]

Reaction rates depend on
Temperature

Order of the reaction
Sum of the exponents

What are the greatest interest of reactions?
Zero, first and second (mainly zero and first)

In First order Rate is proportional to
Concentration

For first order reaction, plot of integrated Ln C vs T... (lnC=lnCoK1t)the slope is what?
K1

Example of pseudo first order degradation
Ester Hydrolysis

Pseudo first order equation
dCE/dt= kCE

Zero Order equation
dC/dt=kC^0

Zero order graph equation
C=Cokot
 Co is intercept
 slope is ko

To maintain constant concentration for zero order
There is a resevoir of drug to replac the drug that is lost to decomposition

Effects of pH on degradation rate
Protons and hydroxyl ions can catalyze reactions (Ester hydrolysis)

Max stability is located where at the graph?
Where log k is at its lowest.

Temperature affect on degradation rates.... 10 Celcius increase causes
25 fold decay rate increase

Arrhenius equation
k=Ae^Ea/RT

Arrhenius used to predict
Shelf life for normal conditions

Ampicillin freezing causes
Pockets of increased conc. causeing increased degradation rate

buffers in solution when freezing
Can alter pH during freezing process.