Chemical Kinetics and Stability

Question 1

what must be known to ensure that the patient receives the correct dose of a drug?

Answer 1

rate of degradation

Question 2

chemicals in nature and take place at definitive rates

Answer 2

degradative reactions

Question 3

the study of rate of a chemical reaction

Answer 3

chemical kinetics

Question 4

speed of a chemical reaction

Answer 4

reaction rate

Question 5

chemical kinetics deals with the ___________ and the mode of action of their degradation through the _______________

Answer 5

stability of drugs, examination of rate of reaction

Question 6

what can chemical kinetics provide to anticipate stability problems?

Answer 6

predictive information

Question 7

Reactions occur when reactant molecules
“effectively collide.”

Answer 7

collision theory

Question 8

facilitate the breaking and forming of bonds and the rearrangement of atoms

Answer 8

effective collision

Question 9

A + BX -> B + AX

Answer 9

effective collision

Question 10

factors that affect reaction rates

Answer 10

• concentration effects
• temperature effects
• catalyst effects

Question 11

*More reactant particles that collide
→the more often a reaction can occur

Answer 11

concentration effects

Question 12

the reaction rate usually increases as the concentration of the reactants _____

Answer 12

increases

Question 13

*Increase in temperature
→Increase in KE
→Faster molecules
→More collision
*The reaction rate of virtually all reactions
increases with increasing temperature.

Answer 13

temperature effects

Question 14

• a substance that increases the reaction rate without undergoing a net chemical change itself
• Lowers Ea

Answer 14

catalysts

Question 15

formula for reaction rate (law/expression/equation)

Answer 15

= aA + bB -> cC + dD
= 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏

Question 16

what is the k in 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏 ?

Answer 16

rate constant

Question 16

what is the A and B in 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏 ?

Answer 16

concentration of reactants

Question 17

what is the a + b in 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏 ?

Answer 17

order of reaction

Question 18

equation of the line:

Answer 18

= y = mx + b
= 𝑪=−𝒌𝒕+𝑪𝟎

Question 19

what is the k in 𝑪=−𝒌𝒕+𝑪𝟎

Answer 19

rate constant

Question 20

what is the Co in 𝑪=−𝒌𝒕+𝑪𝟎

Answer 20

initial concentration

Question 21

formula for rate constant (select the last two points)

Answer 21

𝒎= 𝐶2 −𝐶1 / 𝑡2 −𝑡1

Question 22

the time required for one-half (50%) of the material to disappear

Answer 22

half-life (t 1/2)

Question 23

formula for half life (zero order)

Answer 23

𝒕𝟏/𝟐 = (𝟎.𝟓)(𝑪𝒐) / 𝒌

Question 24

the time required for 10% of the material to disappear

Answer 24

shelf-life (t90)

Question 25

formula for shelf life (zero order)

Answer 25

𝒕𝟗𝟎 =(𝟎.𝟏)(𝑪𝒐) / 𝒌

Question 26

A plot of the remaining drug concentration, C versus t, gives a

Answer 26

curved line

Question 27

However, a plot of natural logarithm of drug concentration, ln C vs t, gives a ________ with a slope equal to -k.

Answer 27

straight line

Question 28

formula for rate constant (with natural logarithm)

Answer 28

𝒎= (𝑙𝑛𝐶2 −𝑙𝑛𝐶1) / (𝑡2 −𝑡1)

Question 29

formula for half life (first-order)

Answer 29

t1/2 = 0.693 / k

Question 30

formula for shelf life (first order)

Answer 30

t90 = 0.105 / k

Question 31

Application of Chemical Kinetics in Pharmacy

Answer 31

1. production of more stable drug preparations, the dosage and rationale of which may be established on sound scientific principles 2. assist the physician and patient regarding the proper storage and use of medicinal agents.

Question 32

the time period during which a drug product is expected to remain within the approved specification for use, provided that it is stored under the conditions defined on the container label.

Answer 32

shelf life

Question 33

the date placed on the container label of a drug product designating the time prior to which a batch of the product is expected to remain within the approved shelf-life specification

Answer 33

expiration date

Question 34

determination of shelf-life

Answer 34

1. arrhenius equation 2. Q10 method

Question 35

used to predict temperature stability

Answer 35

Arrhenius Equation

Question 36

can estimate the effect of a 10° rise in temperature on the stability of pharmaceuticals

Answer 36

Q10 Method

Question 37

evaluation of stability of drug products

Answer 37

1. accelerated stability studies 2. stress testing

Question 38

designed to increase the rate of chemical degradation or physical change of a drug or drug product by using exaggerated storage conditions

Answer 38

accelerated stability studies

Question 39

carried out under more severe conditions than those used for accelerated testing - High temperature, humidity, high or low pH

Answer 39

stress testing

Question 40

a chemical bond is split via the addition of water e.g. esters and amides Protection: 1. pH buffers 2. Type of solvent 3. Structure modification

Answer 40

hydrolysis

Question 41

transfer of electrons e.g. steroids, vitamins, antibiotics Protection: 1. Low O2 content 2. Antioxidants 3. pH buffers 4. Type of Solvent

Answer 41

oxidation

Question 42

absorption of radiant energy in the form of light e.g. nifedipine, hydrocortisone Protection: 1. Storage condition

Answer 42

photolysis