Buffer Capacity

Question 1

Buffer capacity

Answer 1

The magnitude of the resistance of a buffer to pH changes is referred to as the buffer capacity ().

Buffer capacity is the amount of acid/ base that can be added to a buffer without causing a large change in pH.

Measure of the buffers’ ability to resist changes in pH

Question 2

What is the buffer capacity known as

Answer 2

Buffer efficiency/ buffer index/ buffer value

Question 3

True or False
Pharmaceutical solutions are buffered to a low capacity

Answer 3

True
To protect the drug

Question 4

Effect of high capacity

Answer 4

In eye drops, if high capacity is used, it’ll try changing the pH of the eye, causing irritation

Question 5

Relation between the buffer capacity and the concentration of the buffer components

Answer 5

Directly propotional

Question 6

True or False
The smaller the pH change in a solution after the addition of a specific amount of acid or base, the smaller the buffer capacity of the solution.

Answer 6

False
The smaller the pH change in a solution after the addition of a specific amount of acid or base, the greater the buffer capacity of the solution.

Question 7

True or False
buffer capacity of a solution is a fixed value

Answer 7

False
buffer capacity of a solution is not a fixed value
It will decrease with the external addition of acid or base

Question 8

What’s more important in a drug is it the pH or the buffer capacity?

Answer 8

The buffer capacity

Question 9

True or False
Each buffer works better at a certain pH range

Answer 9

True

Question 10

Can we use phosphate buffers in the eye?

Answer 10

No

Question 11

Prepare a buffer solution of pH 5.0 having a capacity of 0.02.

Answer 11

Slide 27/28

Question 12

The selection of the buffer system depends on:

Answer 12

• pH range and buffer capacity required
• purpose of use (topical or IV)
• compatibility and level of toxicity

Question 13

The borate buffer is used in the _______, and can’t be used in the _______.

Answer 13

Eye preparations, IV injections

Question 14

Borate and phosphate buffers are incompatible with many compounds, including:

Answer 14

Salts of silver, iron, magnesium, and zinc

Question 15

Borate buffers form complexes with many excipients, such as:

Answer 15

Glycerol and carbohydrates

Question 16

Borate buffer is composed of

Answer 16

Boric acid
Sodium Borate

Question 17

Difference between in vitro and in vivo

Answer 17

In vitro - in the lab
In vivo - inside a living organism

Question 18

Buffers in the blood

Answer 18

Primary buffers
Secondary buffers

Question 19

Primary buffers

Answer 19

In the plasma
Carbonic acid/ bicarbonate
Phosphoric acid/ sodium phosphate
Plasma proteins (such as glycoproteins)

Question 20

How can the plasma proteins, such as glycoproteins, act as buffers?

Answer 20

They behave as acids in the blood and can combine with bases, which make them act as buffers

Question 21

Secondary buffers

Answer 21

In the erythrocytes
Haemoglobin (acid)/ oxyhemoglobin(salt)
Phosphoric acid/ potassium phosphate

Question 22

Minimum and maximum pH of the blood

Answer 22

6.9 - 7.8

Question 23

What is the lachrymal fluid?

Answer 23

Tears

Question 24

Lachrymal fluid buffer capacity

Answer 24

Have a great degree of buffer capacity

Question 25

Dilution value of lachrymal fluid

Answer 25

15
a dilution of 1:15 with neutral distilled water is possible before an alteration of pH is noticed. This would be referred today as dilution value rather than buffer capacity.

Question 26

pH of tears

Answer 26

7.4
7-8
However, CO2 in the air makes conjunctival fluid more acidic

Question 27

Minimum and maximum pH of the lachrymal fluid

Answer 27

6.6 - 9

Question 28

Effect of phosphate buffer on the eye

Answer 28

phosphate buffer produced irritation in the eyes, due to its high capacity

Question 29

Buffers in the parenteral solution

Answer 29

Parenteral solutions for injection into the blood are usually NOT buffered or buffered to a low capacity so that the buffers of the blood may readily bring them within the physiologic pH range, due to the large volume of thhe blood

Question 30

pH of the urine

Answer 30

6

Question 31

Minimum and maximum pH of the urine

Answer 31

4.5-7.8

Question 32

Response of the kidney to the pH of the urine

Answer 32

When the urine pH is below normal values, hydrogen ions are retained by the kidneys and when the urine pH is above 7.4, hydrogen ions are excreted by the kidneys to return the pH to its normal value.

Question 33

What can alter the pH of the urine?

Answer 33

Some food and drinks

Question 34

pH of the human body

Answer 34

7-8

Question 35

Rrange of the pH in the body

Answer 35

1-10

Question 36

HCl buffer consists of

Answer 36

Hydrochloric acid
Potassium chloride
Sodium chloride

Question 37

Why is potassium chloride added to the HCl buffer?

Answer 37

Adjust the ionic strength

Question 38

Influence of Buffer Capacity and pH on Tissue Irritation

Answer 38

•The lower the buffer capacity of the pharmaceutical solution.
•The smaller the volume of the pharmaceutical solution used.
•The larger the volume and buffer capacity of the physiological fluid where pharmaceutical solution is used..

Question 39

Weak acidic drug ionise in which medium?

Answer 39

Basic medium

Question 40

Which ffoorm of the acid is soluble

Answer 40

Ionic form

Question 41

Which form of the buffer is soluble

Answer 41

Ionic form

Question 42

Which form of the buffer will pass to the cells through the ppm

Answer 42

Non ionized
Ionized dissolve in water

Question 43

True or false
The buffer stay non ionic at the same pH

Answer 43

True

Question 44

True or False
it is important that the drug will be in unionized form in the part of the body where it is placed to be absorbed.

Answer 44

True
So it can pass through the cell

Question 45

Choice of buffer depends on

Answer 45

the desired pH and buffering capacity, compatibility with other excipients, toxicity