the medicine

Question 1

what are sink conditions?

Answer 1

1) where the solute may be removed from solution at a faster rate than it is produced

2) the volume of the solution maybe so large that C does not exceed 10% of Cs

in this case (Cs-C)≈Cs

Question 2

What are non-sink conditions

Answer 2

where C exceeds 10% of Cs

Question 3

When does the overall dissolution rate equal zero

Answer 3

when C=Cs

The solution is saturated with solute

Question 4

what is the significance of Noyes-Whitney

Answer 4

The Noyes-Whitney function is used to represent how the solid material is dissolved into solution

Question 5

what is dissolution?

Answer 5

Dissolution is the process where a solute in gaseous, liquid, or solid phase dissolves in a solvent to form a solution.

Question 6

what is the Noyes-whitney equation

Answer 6

dm/dt = D.A.dC/dx

Question 7

what is dm

Answer 7

change in mass [mg]

Question 8

what is dt

Answer 8

Change in time [seconds.]

Question 9

what is D

Answer 9

The diffusion coefficient (cm^2/s)

Question 10

what is A

Answer 10

surface area (cm^2)

Question 11

what is dC

Answer 11

change in concentration (mg/cm^3)

Question 12

what is dx

Answer 12

change in distance (cm)

Question 13

what does dC/dx describe

Answer 13

The concentration gradient

where: dC/dx = Cs-C/h

Question 14

what is the notes-whitney equation for a single Spherical particle

Answer 14

dm/dt = D.A.(Cs-C)/h

Question 15

What is viscosity?

Answer 15

The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of “thickness”: for example, syrup has a higher viscosity than water.

Question 16

What happens to the rights of dissolution when the diffusion coefficient is decreased?

Answer 16

The rate is also decreased [this can happen when viscosity is increased.]

Question 17

what happens to the rate of dissolution if the particle size is increased? (A)

Answer 17

The rate decreases

Question 18

what is Cs

Answer 18

the saturation solubility of the drug in solution in the diffusion layer

Question 19

what is C

Answer 19

Drug concentration in bulk solution
at time t (g/mL)

Question 20

What is a solution?

Answer 20

A special type of homogenous mixture, composed of two or more substances

Question 21

What are some advantages of a solution in pharmacy?

Answer 21

easier to swallow than solids
Absorption is rapid
The onset of action is faster than solid dosage forms
Homogenous dosage
Attractive mouth feel and appearance

Question 22

What are some disadvantages of a solution in pharmacy?

Answer 22

they are bulky to transport
The dosage is dependent on the patient’s ability
Possible microbial contamination
May require taste mashing
Less stable than solid dosage forms

Question 23

what are some examples of a solvent [aqueous solutions]

Answer 23

water, is the most widely used solvent/cosolvent

Question 24

What are some examples of a solvent [nonaqueous solution]

Answer 24

oils, alcohols, glycols

Question 25

what is dissolution? [uni definition.]

Answer 25

It is a process/transfer of molecules and ions from a solid state to a solution

Question 26

What is solubility?

Answer 26

A Physio chemical property of molecules [drugs] It depends on the balance of lipophilic and hydrophilic groups And how much of a drug is dissolving in a specific volume?

Question 27

What does having a higher intrinsic solubility mean?

Answer 27

there are more hydroxyl groups, more hydrophilic groups. Which increase the affinity between the molecule and the solvent. More of the molecule in the solvent is packed in before reaching saturation

Question 28

what is the effect of pH on the solubility of acids? Increasing the pH:

Answer 28

This will increase solubility due to increased interaction of the ionized form with water. The acids will donate to the protons, and become more charged.

Question 29

what is the effect of pH on the solubility of bases? Decreasing the pH of a solution containing bases

Answer 29

decreasing the pH of solutions, containing bases will cause ionization This will increase solubility, due to an increased interaction of the ionized form

Question 30

What is a partitioning coefficient?

Answer 30

They describe the distribution of solvents between a mixture of immiscible liquids

Question 31

What is an immiscible liquid?

Answer 31

where to liquids stay as two different layers

Question 32

What is the partition coefficient equation?

Answer 32

P=Co/Cw [] of the top / [] of the bottom liquid

Question 33

How do we know if the molecule is more hydrophilic or lipophilic by using the partition coefficient?

Answer 33

we logP logP>0 = the molecule is more lipophilic logP<0 = the molecule is more hydrophilic. [polar].

Question 34

Gastrointestinal absorption the two main classes

Answer 34

there are two main classes of transport through the gastrointestinal tract/membrane 1) passive 2) carrier mediated Passive transport [diffusion] is driven by a concentration gradient

Question 35

Why is the gut membrane more permeable to un ionized forms of drugs?

Answer 35

due to a greater liquid solubility, and they are usually smaller molecules. That is also no charge effects There is rapid absorption when the drugs is un ionized

Question 36

when are acids usually absorbed

Answer 36

from a low pH For example, the stomach

Question 37

when are bases usually absorbed

Answer 37

from a higher pH/environment For example, the intestine

Question 38

Why is absorption from the stomach not extensive?

Answer 38

because of the muscle lining, small surface area, short residence time

Question 39

Why is the small intestine a more favorable environments for absorption?

Answer 39

because of a large surface area, thin barrier, long residence time

Question 40

what is residence time

Answer 40

the duration of persistence of a mass or substance in a medium or place The amount of time, a molecule or substance has stayed in somewhere (the longer it has stayed the more likely it is favorable for absorption)

Question 41

what is the %ionized calculation

Answer 41

%ionised = (I/I+U) X 100 I=amount of ionised drug U= amount of unionized drug

Question 42

what is the % ionised equation for acids

Answer 42

% ionised = 100/1+10^pKa-pH

Question 43

what is the % ionised equation for bases

Answer 43

% ionised = 100/1+10^pH-pKa