BME 6210 E1 TEST WITH
COMPLETE SOLUTION
FDA Shelf Life - ANSWER 90+% Potency from day drug is made
Look and effect must remain the same since day made
Measuring Drug Potency - ANSWER Adding stressors
*Changing temperature
*Changing humidity are the main ones
Mechanical/Physical Stress
Temperature Stress Range - ANSWER 4, 20,30, 37, 50, 75 C
Humidity Stress Range - ANSWER 30, 45, 60, 75, 90% relative humidity
Physical Stresses - ANSWER Mechanical
Chemical
Thermal
Most common Degradation Reactions - ANSWER Hydrolysis
Oxydation
Photolysis
Zero Order Reaction - ANSWER Constant reaction rate
Rate Equations
, [A] = [A]o-ko*t
-d[A]/dt=ko
90% Life
t90 = 0.1[A]o/ko
Half-Life
t50=[A]o/2ko
Graph
[A] v t, neg linear with k0 = slope
Pseudo Zero Order - ANSWER Solid state of drug in liquid solution and it
dissolves to replace degraded drug.
[Drug] is same
Degradation will plateau when SS drug dissolves
First Order Reaction - ANSWER Rate Eqns
-d[A]/dt=[A]k1
ln[A]=ln[A]o-k1*t
90% Life
t90 = 0.105/k1
Half Life
0.693/k1
Graph
, [A] v t, concave up negative Slope
ln[A] v t, linear neg with k1 = slope
Temperature Dependence (Predicting Shelf Life) - ANSWER Assuming First
Order:
1) Find k1 at different temperatures: ln[Drug] v t
-What doesn't have a slope = stability at that temperature
2) Plot lnk1 v t to predict k1 at lower temperatures that didn't have slope in
above graph
3) Use to find Arrhenius Eqn (if ks linear) to describe rxn rt and T
relationship.
Arrhenius equation - ANSWER lnk = lnA - E/RT
E = Activation Energy
R = Gass Constant
T = Temperature (K)
A = NON DRUG constant
Nonlinear Arrhenius - ANSWER -Concave UP: Change in degradation Method
Ex: At higher temperatures in the G v rxn progress graph, one mechanism has
lower Gibbs Free E and is therefore dominant and at lower temperatures its
flipped.
-Concave Down: Change in Rt Lim Step (RLS)
pH v Rt Curve - ANSWER -In plotting log(kobs) v pH, the most stable pH is
COMPLETE SOLUTION
FDA Shelf Life - ANSWER 90+% Potency from day drug is made
Look and effect must remain the same since day made
Measuring Drug Potency - ANSWER Adding stressors
*Changing temperature
*Changing humidity are the main ones
Mechanical/Physical Stress
Temperature Stress Range - ANSWER 4, 20,30, 37, 50, 75 C
Humidity Stress Range - ANSWER 30, 45, 60, 75, 90% relative humidity
Physical Stresses - ANSWER Mechanical
Chemical
Thermal
Most common Degradation Reactions - ANSWER Hydrolysis
Oxydation
Photolysis
Zero Order Reaction - ANSWER Constant reaction rate
Rate Equations
, [A] = [A]o-ko*t
-d[A]/dt=ko
90% Life
t90 = 0.1[A]o/ko
Half-Life
t50=[A]o/2ko
Graph
[A] v t, neg linear with k0 = slope
Pseudo Zero Order - ANSWER Solid state of drug in liquid solution and it
dissolves to replace degraded drug.
[Drug] is same
Degradation will plateau when SS drug dissolves
First Order Reaction - ANSWER Rate Eqns
-d[A]/dt=[A]k1
ln[A]=ln[A]o-k1*t
90% Life
t90 = 0.105/k1
Half Life
0.693/k1
Graph
, [A] v t, concave up negative Slope
ln[A] v t, linear neg with k1 = slope
Temperature Dependence (Predicting Shelf Life) - ANSWER Assuming First
Order:
1) Find k1 at different temperatures: ln[Drug] v t
-What doesn't have a slope = stability at that temperature
2) Plot lnk1 v t to predict k1 at lower temperatures that didn't have slope in
above graph
3) Use to find Arrhenius Eqn (if ks linear) to describe rxn rt and T
relationship.
Arrhenius equation - ANSWER lnk = lnA - E/RT
E = Activation Energy
R = Gass Constant
T = Temperature (K)
A = NON DRUG constant
Nonlinear Arrhenius - ANSWER -Concave UP: Change in degradation Method
Ex: At higher temperatures in the G v rxn progress graph, one mechanism has
lower Gibbs Free E and is therefore dominant and at lower temperatures its
flipped.
-Concave Down: Change in Rt Lim Step (RLS)
pH v Rt Curve - ANSWER -In plotting log(kobs) v pH, the most stable pH is
