Modified Release 1-5 + Rectal Admin

Question 1

if Log P is above 0 then the drug is more

Answer 1

hydrophobic

Question 2

if the drug log P is below 0 then it is more?

Answer 2

hydrophilic

Question 3

if we have a very low log P value is this good or bad?

Answer 3

bad - drug will be too hydrophillic and wont pass the stratum corneum

Question 4

whats the equation for flux?

Answer 4

dm/dt= DP Cv/h

where D(diffusion coefficient) takes into account molecular weight

P(permeability coefficient) takes into account hydrophobicity

Cv is the concentration of drug in vehicle

h is thickness of skin (thicker is more difficult to get across)

Question 5

Tell me about MST and its composition

Answer 5

MST is slow release morphine.

Has hydrophobic matrix and hydrophilic granules. Combination because can release drug by dissolution and diffusion

Hydrophilic granules contain theophylline (coated)

hydophibic matrix has compressed drug.

1/3 of drug released by diffusion - gives a burst effect

2/3 released by dissolution (going into solution).

Question 6

How do Osmotic tablets work?

Answer 6

Reservoir contains the drug

Water enters the chamber -> osmotic pressure increases

reservoir compresses and contrcts to release drug through the orifice.

The chamber contrains an osmotic agent, e.g NaCl

The membrane is semi-permeable, only to water entrance.

Question 7

controlled release of MST is dependent on

Answer 7

The control of this system depends on two factors:

• Dissolution of the higher aliphatic alcohol, and
• Diffusion of the active principle through in vivo hydration of the hydroxyalkyl cellulose