Chemical Kinetics and Stability Flashcards

1
Q

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

A

rate of degradation

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2
Q

chemicals in nature and take place at definitive rates

A

degradative reactions

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3
Q

the study of rate of a chemical reaction

A

chemical kinetics

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4
Q

speed of a chemical reaction

A

reaction rate

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5
Q

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

A

stability of drugs, examination of rate of reaction

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6
Q

what can chemical kinetics provide to anticipate stability problems?

A

predictive information

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7
Q

Reactions occur when reactant molecules
“effectively collide.”

A

collision theory

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8
Q

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

A

effective collision

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9
Q

A + BX -> B + AX

A

effective collision

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10
Q

factors that affect reaction rates

A
  • concentration effects
  • temperature effects
  • catalyst effects
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11
Q

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

A

concentration effects

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12
Q

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

A

increases

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13
Q

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

A

temperature effects

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14
Q
  • a substance that increases the reaction rate without undergoing a net chemical change itself
  • Lowers Ea
A

catalysts

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15
Q

formula for reaction rate (law/expression/equation)

A

= aA + bB -> cC + dD
= 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏

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16
Q

what is the k in 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏 ?

A

rate constant

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16
Q

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

A

concentration of reactants

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17
Q

what is the a + b in 𝑟𝑎𝑡𝑒=𝑘[𝐴]𝑎[𝐵]𝑏 ?

A

order of reaction

18
Q

equation of the line:

A

= y = mx + b
= 𝑪=−𝒌𝒕+𝑪𝟎

19
Q

what is the k in 𝑪=−𝒌𝒕+𝑪𝟎

A

rate constant

20
Q

what is the Co in 𝑪=−𝒌𝒕+𝑪𝟎

A

initial concentration

21
Q

formula for rate constant (select the last two points)

A

𝒎= 𝐶2 −𝐶1 / 𝑡2 −𝑡1

22
Q

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

A

half-life (t 1/2)

23
Q

formula for half life (zero order)

A

𝒕𝟏/𝟐 = (𝟎.𝟓)(𝑪𝒐) / 𝒌

24
Q

the time required for 10% of the material
to disappear

A

shelf-life (t90)

25
Q

formula for shelf life (zero order)

A

𝒕𝟗𝟎 =(𝟎.𝟏)(𝑪𝒐) / 𝒌

26
Q

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

A

curved line

27
Q

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

A

straight line

28
Q

formula for rate constant (with natural logarithm)

A

𝒎= (𝑙𝑛𝐶2 −𝑙𝑛𝐶1) / (𝑡2 −𝑡1)

29
Q

formula for half life (first-order)

A

t1/2 = 0.693 / k

30
Q

formula for shelf life (first order)

A

t90 = 0.105 / k

31
Q

Application of Chemical Kinetics in Pharmacy

A
  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.
32
Q

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.

A

shelf life

33
Q

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

A

expiration date

34
Q

determination of shelf-life

A
  1. arrhenius equation
  2. Q10 method
35
Q

used to predict temperature stability

A

Arrhenius Equation

36
Q

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

A

Q10 Method

37
Q

evaluation of stability of drug products

A
  1. accelerated stability studies
  2. stress testing
38
Q

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

A

accelerated stability studies

39
Q

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

A

stress testing

40
Q

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

A

hydrolysis

41
Q

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

A

oxidation

42
Q

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

A

photolysis