Controlling Drug Delivery

Type of Controlling Drug Delivery systems (controlled delivery drugs) are,

1. Immediate release (IR)

Allows the medicine to dissolve in the gastrointestinal contents, with no purpose of delaying or prolonging the dissolution or absorption of the drug.

Dosage forms whose drug release features of time course and/or location of the body are preferred to achieve therapeutic or convenience objectives not offered by conventional dosage forms such as a solution or an immediate-release dosage form.
Modified-release solid oral dosage forms consist of Delayed & Extended-Release drug products.
The modified-release systems can be further divided into,
- A. Delayed
- B. Extended
- C. Targeted-release systems.

Delayed-release (DR) systems can be used to protect drugs from a breakdown in the stomach’s low pH environment or to protect (shield) the stomach from medication discomfort.

Various Unit related DR medication
- Multiple-unit: A multiple unit dosage forms contain a variety of units e.g. pellets or beads. Every units covering release controlling excipients, e.g. in a Gelatin capsule or compressed in a tablet.
- Single-unit: The single-unit dosage forms contain of only one unit, e.g. osmotic tablet.

Extended-release products are formulated to make the drug available over an extended period after digestion.
When compared to a medicine delivered in a traditional dosage form, this allows for a reduction in dosing frequency (e.g. as a solution or an immediate-release dosage form).
Extended-release systems can be further divided into
- a. Sustained release (SR)
- b. Controlled release (CR) systems.

Sustained release means: Drug Delivery systems that keep the rate of drug release over a sustained period.
For example, if drug release from the dosage form is sustained across the whole gastrointestinal tract, C_max can be reduced and the time interval between drug concentrations in the therapeutic range can be extended.
This in turn may decrease the frequency of dosing.
Sustained Release Drug Use : With sustained release, a specific medicine can be administered at a set rate, resulting in long-lasting drug delivery. This method of drug release is particularly helpful for medications that are digested too quickly and leave the body soon after taking them.

Controlled-release systems have a sustained-release profile as well, but unlike sustained-release systems, they are designed to produce predictable consistent plasma concentrations regardless of the biological milieu at the application site. This means that, unlike a sustained-release method, they are truly managing the drug concentration in the body, not only the release of the medication from the dosage form.
Another difference between sustained- and controlled-release dosage forms is that the former is basically restricted to oral dosage forms on other hand, controlled-release systems are used in various administration routes, including vaginal, transdermal, oral administration.
Zero Order release kinetics.
Sustained release (SR) keeps drug release over a sustained period but not at a constant rate.
Controlled-release (CR) keeps drug release over a sustained period at a nearly constant rate.

Targeted drug delivery, sometimes called smart drug delivery, is a method of delivering drugs to a patient in a manner that raises the concentration of the drugs in some parts of the body relative to other parts of the body.
This delivery technique is mostly based on nanomedicine, so which intends to use nanoparticle-mediated drug delivery to overcome the drawbacks of traditional drug delivery.

Chart:

Prolonged release (PR) drug system is long time releasing system and extended release (ER) drug delivery system is used for extends the releasing time of drug.
Example of Extended-release (ER) :
- Venlafaxine Extended-Release Tablets
Example of Sustained Release tablets:
- Quel SR 100mg Tablet
- Calan SR (verapamil ER)

Immediate Release (IR) product release instant to the body (without delaying or prolonging dissolution or absorption). Some disease required instant medication, in this case IR medicine is required.
Extended Release Drug delivery system is that over a extended period release of drug occur. In some disease medication in blood stream required to maintain over a time in this case ER is good option.

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