Controlled Release W9 Flashcards
Why oral drug delivery as a root of administration?
Ease of administration
Non-invasive
Adopted different dosage forms such as sachets, powder, suspension, tablet
No special formulation required, i.e. sterility
Why do we need modified/controlled release dosage forms?
In case of chronic conditions, e.g. hypertension, diabetes
Drawbacks of modified release
Drug – blood level fluctuation
Poor patient compliance
No inconvenient with drugs with short half lives
Live therapeutic outcome
Advantages of modified release
Improved therapeutic efficiency by maintaining drug plasma level within therapeutic range for an extended period of time
Minimise side effects by reducing dosing frequency
Increased patient compliance and inconvenience
Reduce overall treatment cost for chronic disease
Disadvantages and limitations of modified products
The rate of transit of MR products along the gastrointestinal tract limits the maximum period for a therapeutic response to be maintained following administration of a single dose to approximately 12 hours
MR products cost more per unit dose
Safety concern of dose dumping as MR products contain a larger total amount of drug
Candidate drugs for controlled DDS
Low therapeutic dose
High therapeutic index
Moderate solubility
Stable in GIT
High absorption
Moderate half-life (2–8 hours)
Parliament membrane diffusion systems/membrane reservoir systems
Comprise a drug reservoir enclosed within a polymeric coating
Drug release is controlled by diffusion governed by fick’s diffusion law
Drug release is dependent on the drug concentration in the reservoir
Polymer matrix diffusion systems/diffusion monolith systems
Drug release is controlled by diffusion through a polymer matrix
Polymer matrix dissolution systems
Drug release is controlled by the dissolution rate of the soluble matrix polymer
Ion exchange resin systems
The drug forms a complex with the resin to create an insoluble compound
In the GIT ions present can exchange with the drug ions leading to a gradual release of the drug
Approaches for delayed release DDS
Time systems
PH control system systems
Enzyme triggered
How do we know what the dosage form is doing in the body?
Measure blood levels as a function of time
Image dosing form in the body
