null

US

4964927

3.) Pharmaceutical Formulations
2

- INTRINSIC DISSOLUTION RATE (IDR)
- What is Intrinsic Dissolution Rate?
- The rate of dissolution is dependant on many
variables such as pH, viscosity, temperature etc.
Intrinsic dissolution rate is independant of these
variables

- The rate of dissolution is dependant on many
variables such as pH, viscosity, temperature etc.
Intrinsic dissolution rate is independant of these
variables
- How is it calculated?
- The Noyes Whitney equation is rearranged
so that area variable is kept constant
within the equation
- The equation can then be further simplified by
introducing the intrinsic dissolution rate constant (K)
- K takes care of D/h, Units = cm/s

- K takes care of D/h, Units = cm/s
- Simplied equation therefore:

- The Noyes Whitney equation is rearranged
so that area variable is kept constant
within the equation
- Example Questions
- 1.) When calculating anything using the IDR equation, you
have to first decide whether or not sink conditions apply.
This is done by working out 10% of Cs and then seeing how
it compares with C. If C less than 10% then sink applies
- 2.) If sink conditions apply then Cs-C becomes simply Cs
- 3.) Then convert all of the units so that they are the
same or similar
- 4.) Plug the values into the equation. The equation may
need to be rearranged

- 1.) When calculating anything using the IDR equation, you
have to first decide whether or not sink conditions apply.
This is done by working out 10% of Cs and then seeing how
it compares with C. If C less than 10% then sink applies
- Why do you measure IDR?
- This is measured to know what the rate of dissolution would be if
all variables were kept at a certain constant. So that if the rate of
dissolution does change we know that at least one of the
variables has changed
- This allows you to know how new drugs will
act when all variables are kept constant

- This allows you to know how new drugs will
act when all variables are kept constant

- This is measured to know what the rate of dissolution would be if
all variables were kept at a certain constant. So that if the rate of
dissolution does change we know that at least one of the
variables has changed
- Dissolution Apparatus
- What does it do?
- This allows you to see how drugs will act
when in conditions similar to the human
body more specifically the small
intestines

- This allows you to see how drugs will act
when in conditions similar to the human
body more specifically the small
intestines
- Methods
- Static Disc Method
- Can also be rotating disc method
- Apparatus
- Temperature is
37 degree as this
is human body
temperature
- Rotating paddle is used to make
the fluidity similar to that of the
intestines
- Drug is compressed to ensure there are no
pores in the drug so solution cannot affect
dissolution

- Temperature is
37 degree as this
is human body
temperature

- Can also be rotating disc method

- Static Disc Method

- What does it do?

- What is Intrinsic Dissolution Rate?
- Hixson-Cromwell Cube Root Law
- Why is this used to the Noyes
Whitney Equation?
- The Noyes Whitney equation assumes that the
surface area of the particles remain constant but
in practice they dont. This equation takes into
account the changing surface area

- The Noyes Whitney equation assumes that the
surface area of the particles remain constant but
in practice they dont. This equation takes into
account the changing surface area
- What is the equation?
- It can be arranged in such an
equation for a straight line
graph
- The equation says that the cube root of the undissolved
mass at time, t is the same as the cube root of mass at
the start minus cube root dissolution constant

- It can be arranged in such an
equation for a straight line
graph
- Example Question
- For this question you fill out a table like so. first you
work out the undissolved using the concentration.
Then find the dissolved. Finally cube root the
dissolved to to get the final answer

- Why is this used to the Noyes
Whitney Equation?

- a5c29afe-d6a9-453d-9fe2-15a6d41cd0ed (image/png)
- de7b04dc-ba57-41f8-b020-eda91fbabe57 (image/png)
- 9f5da4ee-cb5b-44f9-b6a7-ee0df55e8eb1 (image/png)
- ba75fd4f-b690-4428-9ae4-9dc113f6e9d5 (image/png)
- a0feca31-e47e-4b89-b216-36857bb8a939 (image/png)
- 495f6a54-9b03-4d61-93a3-cb723c4b39ea (image/png)
- e54c2949-a08b-40cd-9289-89f364dfc155 (image/png)
- e588ceab-142d-4f04-bf77-95ff8e8b4d79 (image/png)
- 9fabe8c3-0084-45a4-904f-b444d1857d8c (image/png)

Want to create your own Mind Maps for **free** with GoConqr? Learn more.