Drug name: VPL874C (Market name = Betatrix)
Possible indications = migraine prophylaxis, hypertension, coronary heart disease
Problem – want oral dosage form.
- but has short half life (3-4hr)
Solution – oral dosage form with extended release which releases drug slowly so that the plasma concentrations are maintained at a therapeutic level for a prolonged period of time (usually between 8 and 12 hours).
Recent extended release formulations possible
pH-sensitive multiparticulate drug delivery system
- how it works:
- a nano-suspension was made from with the drug, and then chitosan bead were made, which were degradable selectively in the colon
Advantage – area specific absorption of drug. And prevent drug form degradation, for non-soluble drugs Disadvantage – not for water soluble drugs (have to make suspension), not for sustained release,
Modified Push-pull osmotic systems –
- how it works
- the system has two compartments, one is hydrogel, and the other is for non-watersoluble drugs with orifice, which diffuses out with the hydrogel absorbs water and pushes the drug out slowly
Advantage – can use two drugs, one being water soluble can be incorporated into the expandable hydrogel. Sustained release. Disadvantage – its better to use with two drugs, or no point of this, epensive,
Controlled drug diffusion for oral extened release by using micelle-forming properties and counter –charge polymer. -how it works:
- a highly water soluble drug was added to a gel forming polymer matrix but with a counter polymer which slows down drug diffusion out of the matrix
Advantage – for water soluble drugs, sustained release, simple to make Disadvantage – not for all water soluble drugs, make sure that counter-charge polymer does not bind with too high affinity to the drug, and does not interact with the drug chemically. Our drug is not charged.
Aqueous-core microcapsules with a defined PLG shell.
How it works:
- encapsulate the drug in microcapsule or in microsphere can either produce a pulsatile release with a surface eroding polyanhydride shell, of a bulk-eroding polyester may provide sustained drug released through the matrix. Advantages – precision particles, sustained release, make different shell thickness to change release rates and times. Disadvantages – mainly for proteins, expensive, hard to scale up and guarantee size uniformity. Entrapment efficiency.
- * Hydrophilic Matrix Systems – or hydrogels
How it works:
-the hydrophilic colloid takes in water and swells to form a hydrated matrix layer – which controls the drug diffusion out of the matrix. Basically, drug is released in 2 ways, through the erosion of the gel matrix, and through diffusion out of the gel matrix.
Hydrogels are hydrophilic macromolecular networks that, after swelling, maintain their shape due to permanent links. The very high water content and special surface properties of the swollen form give them the ability to simulate natural tissues. Hydrogels are very versatile materials . Much interest has been expressed in the application of hydrogels for controlled drug delivery, because they have been shown to be excellent carriers for the release of drugs and bioactive compounds. Particularly when used in a dehydrated state, they undergo glassy to rubbery transition.
Drug delivery technologists usually tend to consider all hydrophilic delivery systems as hydrogels. In fact, the most widely used polymers for drug delivery control, particularly in oral applications, are swellable polymers. These polymers allow the preparation of drug delivery systems that, after transition from the glassy to the rubbery state, differ from hydrogel in so far as they do not maintain a permanent shape. In any case, a common feature is the swelling of the polymer that often results from the glassy-rubbery transition of the dry form. This last property is used...