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Pharmacuetical Calculations > Tutorial 9: buffer capacity > Flashcards

Tutorial 9: buffer capacity Flashcards

1
Q

give different names buffer capacity goes by

A

buffer efficiency, buffer value, buffer index

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2
Q

T or F:
pharmaceutical solutions are buffered to a low capacity

A

truey wuey

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3
Q

T or F:
pharmaceutical solutions are buffered to a high capacity

A

falsy
low capacity

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4
Q

scientific term:
the magnitude of the resistance of a buffer to pH changes

A

buffer capacity (β)

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5
Q

T or F:
boric acid is suitable for eye preparations but not for IV injections

A

truey wuey

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6
Q

T or F:
boric acid is suitable for IV injections but not for eye preparations

A

falsy
the opposite

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6
Q

_____ and _____ buffers are incompatible with any compounds including the salts of silver, iron, magnesium and zinc

A

borate and phosphate

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7
Q

borate and phosphate buffers are incompatible with any compounds including the salts of__,___,___ and ___

A

silver, iron, magnesium and zinc

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8
Q

which salts are borate and phosphate buffers incompatible with?

A

zinc, silver, magnesium and iron salts

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9
Q

____ buffers form complexes with excipients like glycerol and carbohydrates

A

borate

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10
Q

borate buffers form complexes with excipients like ___ and ____

A

glycerol, carbohydrates

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11
Q

T or F:
borate buffers are compatible with excipients like glycerol and carbohydrates

A

falsy
they form complexes with them, not compatible

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12
Q

how is blood pH maintained as 7.4?

A

with the help of primary buffers in blood plasma and secondary buffers (hemoglobin) in erythrocytes

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13
Q

what are the two buffer systems in blood plasma?

A

carbonic acid/bicarbonate and phosphoric acid/sodium phosphate

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14
Q

what are the two buffer systems in erythrocytes?

A

hemoglobin/oxyhemoglobin and phosphoric acid/sodium phosphate

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15
Q

T or F:
lachrymal fluid has great buffer capacity

A

truey

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16
Q

T or F:
β is proportional to the concentration of buffer components added to the solution

A

truey

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17
Q

T or F:
β doesn’t necessarily depend on the ratio of its components

A

falsy
it is proportional to the conc of its components

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18
Q

T or F:
β depends on the pKa of weak acid or base

A

truey

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19
Q

what does β depend on?

A

pKa of acid or base
conc of its components
volume of medium

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20
Q

T or F:
β is a fixed value

A

falsy

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20
Q

the ___ the change in pH change in a solution after adding base/acid, the greater the buffer capacity

A

lower/smaller

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21
Q

T or F:
β will increase with external addition of acid or base

A

falsy
it will decrease because the added acid/base will consume buffer therefore lower the β

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22
Q

T or F:
β will decrease with external addition of acid or base

A

truey because the added acid/salt will consume more buffer

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23
Q

T or F:
the final pH of the buffer is more important than the capacity

A

falsy
β and the volume used in relation to the medium’s volume aremore important

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24
Q

how can β be expressed in terms of amount of stronk acid or base added to change the pH?

A

β equals the amount of stronk acid or base in moles of H+ or OH- per liter, to bring pH down by one unit

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25
Q

when will a buffer have maximum capacity

A

when pKa of weak acid or base is closed to the desired pH
or the ratio of (salt)/acid equals 1
when log (ratio) equals 0

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26
Q

T or F:
all buffers work best at the same pH

A

falsy
each buffer works best at a certain pH

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27
Q

the higher the difference between the pH of the solution and pKa, the ___ the capacity

A

lower

28
Q

T or F:
the higher the difference between the pH of the solution and pKa, the higher the capacity

A

falsy
the lower

29
Q

T or F:
he lower the difference between the pH of the solution and pKa, the higher the capacity

A

truey weuy

30
Q

how many times can you dilute lachrymal fluid before an alteration in pH is noticed?

A

15 times

31
Q

T or F:
how much a solution can be diluted until pH changes is known as buffer capacity or buffer value

A

falsy
that’s dilution value

32
Q

scientific term:
how much a solution can be diluted until pH changes

A

dilution value

33
Q

__ in the air makes makes conjunctival fluid more acidic

A

CO2

34
Q

for eye drops, irritation and discomfort and flow of tears will occur if the pH drops below ___ or above ___

A

6.6, 9

35
Q

T or F:
for eye drops, irritation and discomfort and flow of tears will occur if the pH drops below 6.9 or above 7.8

A

falsy
6.6, 9.

36
Q

phosphate buffer - boric acid soltuion
which one causes discomfort in the eyes?

A

phosphate buffer

37
Q

which buffer is most suitable for the eyes and what is its pH?

A

boric acid solution. pH of 5

38
Q

T or F:
boric acid causes irritation in the eyes because its pH is 5

A

falsy
it causes no discomfort

39
Q

T or F:
phosphate buffer causes irritation in the eyes

A

truey

40
Q

why is boric acid more suitable for the eyes than phosphate buffer?

A
  1. boric acid has a lower buffer capacity
  2. the physiological response to various ion species
41
Q

T or F:
Ophthalmic solutions are usually not buffered or buffered to a low capacity

A

falsy
this applies on parenteral solutions

42
Q

why are parenteral solutions not buffered or buffered to a low capacity?

A

becuase blood buffers will do their job and bring them within the stable pH range

43
Q

what is the normal urine pH for an adult?

A

6

44
Q

what is the range of urine pH?

A

4.8-7.8

45
Q

what does the kidney do when pH of urine is below normal values?

A

retain hydrogen ions

46
Q

what does the kidney do when pH of urine is above normal values?

A

it will excrete hydrogen ions to bring the pH to its normal range

47
Q

T or F:
When the urine pH is below normal values, the kidney will excrete hydrogen ions to bring pH back to normal

A

falsy
kidney does this when pH of urine is higher than normal

48
Q

T or F:
hydrogen ions are retained by the kidneys and when the urine pH is above 7.4

A

truey

49
Q

T or F:
hydrogen ions are retained by the kidneys and when the urine pH is below 4.8

A

falsy
it will retain H+ when pH is above 7.4

50
Q

T or F:
some food and drinks can alter urine pH

A

truey

51
Q

why are strong acids and bases able to act as buffers?

A

because of their high conc of H+ and OH- ions

52
Q

why is KCL added to HCL buffers even though they don’t participate in the buffering?

A

they are added to adjust ionic strength

52
Q

T or F:
potassium chloride is added to HCL buffers to help in buffering

A

no it doesn’t help in buffering but it adjusts ionic strength

53
Q

the pH of the stomach ranges from __ to __ depending on the presence of food in it

A

1, 4

54
Q

the pH of the stomach ranges from 1to 4 depending on ___

A

whether or not there is food in it

55
Q

what does the gastric (digestive) fluid made of?

A

HCL, KCL and NaCl

56
Q

what does the acidic environment of the stomach aid in?

A

digestion + prevention of infection

57
Q

T or F:
the higher the capacity the higher the irritation

A

truey

58
Q

T or F:
the lower the capacity the higher the irritation

A

falsy
the lower the irritation

59
Q

what happens if we use a low capacity buffer on the eyes but add a large volume?

A

irritation, because the higher the volume of pharmaceutical solution used the higher the irritation

60
Q

to avoid irritation, the volume of pharmaceutical solution must be low and has a high capacity

A

falsy
should have low volume and low capacity

61
Q

to avoid irritation, the volume of pharmaceutical solution must be low and has a low capacity

A

Truey

62
Q

T or F:
to avoid irritation, the volume of pharmaceutical solution must be low and has a low capacity whereas physiological fluid should have high volume and high capacity

A

SO TRUEY

63
Q

to avoid irritation, what should be the relationship between capacity and volume of pharmaceutical solution (a) and physiological fluid (b)?

A

(a) must have low V low capacity
(b) must have high V high capacity

64
Q

T or F;
ionized forms of drugs can easily penetrate biological membranes

A

falsy
unionized

64
Q

T or F:
ionized forms of drugs tend to stay in the aqueous environment in the body

A

truey

65
Q

T or F:
unionized forms of drugs can easily penetrate biological membranes

A

truey

66
Q

why can unionized forms of drugs penetrate biological membranes?

A

because BM are lipid, unionized drugs are more lipid soluble while unionized forms are water soluble

66
Q

T or F:
it is important that the drug will be in ionized form in the part of the body where it is placed to be absorbed.

A

falsy
must be unionized

67
Q

it is important that the drug will be in ___ form in the part of the body where it is placed to be absorbed.

A

unionized

Pharmacuetical Calculations (7 decks)

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