What is the mechanism of fickian transport?
Table 1
| Type of material | Type of device | Transport mechanism |
|---|---|---|
| Elast-Eon™ | Drug-eluting stent | Fickian diffusion |
| Polyurethane (Walopur®) | Disk-shaped matrices | Matrix- controlled |
| Poly(urea- urethane) | Microcapsule | Non-Fickian Diffusion |
| PEG modified polyurethane | Dermal patch | – |
What is the mechanism of release?
noun Ethology. a hypothetical control complex in the central nervous system of animals that triggers the appropriate behavioral response to a releaser.
How do you get a zero order drug release?
Zero-order release can be achieved, in principle, by surrounding the tablet core with a polymer membrane that is permeable to both drug and water. When the core becomes hydrated in the gastrointestinal tract, the drug will dissolve until it reaches its saturation concentration (i.e., solubility).
What is the difference between fickian and non fickian diffusion?
The main difference between Fickian and Non Fickian Diffusion is the presence or absence of boundaries; there are no boundaries in Fickian diffusion whereas non Fickian diffusion has a sharp boundary separating the highly swollen region from a dry, glassy region.
What is a fickian diffusion?
Simple Fickian diffusion is a process in which the transport of the penetrant (water) is a diffusion process driven by the penetrant concentration gradient. From: Comprehensive Composite Materials, 2000.
What is controlled release mechanism?
Controlled release systems have been developed to improve the temporal and spatial presentation of drug in the body, to protect drug from physiological degradation or elimination, to improve patient compliance, and to enhance quality control in manufacturing of drug products.
What is delayed release system?
Delayed release. Delayed-release dosage forms can be defined as systems which are formulated to release the active ingredient at a time other than immediately after administration.
What does Fick’s law state?
Fick’s law states that the rate of diffusion of a substance across unit area (such as a surface or membrane) is proportional to the concentration gradient.
What is CDDS in pharma?
Controlled Release Drug Delivery System (CDDS)
How do you control drug release?
The main mechanisms to control drug release include complexation, matrix embedment and coated reservoir systems. Complexation may involve ion exchange resins or other adsorption agents.
How does polymer drug delivery work?
Polymeric drug delivery system has defined as a formulation or a device that enables the introduction of a therapeutic substance into the body. It improves its safety and efficacy by controlling the rate, time, and place of release of drugs in the body.
What is difference between delayed release and extended release?
Delayed release Release of a drug (or drugs) at a time other than immediately following oral administration. Extended release Extended-release products are formulated to make the drug available over an extended period after ingestion.
What is difference between prolonged release and extended release?
Prolonged release means long time releasing system while extended release system means system which extends the releasing time. ER and PR are the same and have single functionality of extending the time of release of a drug from dosage forms.
What causes the Fickian diffusion in acoustic waves?
Fickian diffusion occurs when the water penetration rate in the gel is less than the polymer chain relaxation rate. D.S. BallantineJr., E.T. Zellers, in Acoustic Wave Sensors, 1997 The Fickian diffusion described above is relatively easy to analyze, and demonstrates the capabilities of AW devices for monitoring transient uptakes.
What is the difference between Fickian and non-Fickian diffusion?
In non-Fickian diffusion (Figs. 6.19 and 6.20 ), moisture uptake may initially exhibit characteristics similar to Fickian diffusion (i.e., relatively rapid with constant diffusivity), but it can eventually slow down and exhibit variable diffusivity.
What is the Fickian behavior of polymers at low temperatures?
In Fickian behavior the diffusion rate of the penetrant is considerably lower than the rate of relaxation processes of the polymer. However, at temperatures below Tg in both glassy and semicrystalline polymers there are considerable deviations from Fickian performance.
How does surface concentration change during Fickian diffusion?
through stress dependence of the flux. A fundamental criterion of Fickian diffusion is that the surface concentration attains its equilibrium value immediately upon a change in conditions and remains constant through the sorption process.