Psychotropic formulations Flashcards
Oil solutions vs Oil suspensions
Oil solution is where drug is dissolved in oily solvent (one phase) and partitions to surrounding aqueous medium for absorption.
Oil suspension is where part of drug is dissolved and part of drug is dispersed undissolved through a continuous phase. It is a two step process, requires dissolution before partitioning to surrounding aqueous medium. Undissolved drug behaves like a reservoir.
Paroxetine hydrochloride tablet
Has a biodegradable barrier layer (enteric coat)
The drug is in a hydrophilic matrix
The paroxetine controlled release drug dose needs to be 25% than that of immediate release as 20% of drug gets retained in the hydrophilic matrix
Fluoxetine hydrochloride capsules
- Have long half-life
- Contain enteric coated pellets
- Doesn’t dissolve until it reaches part of GIT where pH exceeds 5.5
How does an osmotic controlled oral drug delivery system work.
Uses an osmotic pump as a driving force for controlled drug release i.e. methylphenidate
Methylphenidate drug release
Has three compartments - 1. low drug conc 2. high drug conc and 3. push compartment containing reactive water molecules.
It is covered in an overcoat (semi-permeable membrane) from which the drug gets released and water can then enter. The push compartment begins to expand and causes drug release from each compartment respectively at different rates.
Fast dissolving/ disintegrating tablets
Dissolve in the saliva without the need for water.
- May dissolve in saliva or contain an agent that enhances dissolving once in the oral cavity
Matrix systems
Drugs and excipients are uniformly distributed in the adhesive polymer layer. This is how the integrity of the system is maintained.
Reservoir systems
Drugs and excipients are enclosed in the reservoir and the semi-permeable membrane regulates the rate at which the drug diffuses into the skin.
