...release

[ykw]

just wondering the difference between sustained-release, controlled-release, extended-release.... or are these just different names to something similar?

[pharmatron]

These are similar but different dosage forms strictly speaking. Have a look in a Pharmaceutics textbook (e.g. Aulton) for details. From my notes the definitions are as follows:

Delayed release: Indicates that the drug is not being released immediately following administration but at a later time, e.g. EC tablets, pulsatile-release capsules.
Repeat action: Indicates that an individual dose is released fairly soon after administration, and second or third doses are subsequently released at intermittent intervals.
Prolonged release: Indicates that the drug is provided for absorption over a longer period of time than from a conventional dosage form. However, there is an implication that onset is delayed because of an overall slower release rate from the dosage form.
Sustained release: Indicates an initial release of drug sufficient to provide a therapeutic dose soon after administration, and then a gradual release over an extended period.
Extended release (ER): Dosage forms release drug slowly, so that plasma concentrations are maintained at a therapeutic level for a prolonged period of time (usually between 8 and 12 hours).
Controlled release (CR): Dosage forms release drug at a constant rate and provide plasma concentrations that remain invariant with time.
Modified release (MR): Dosage forms are defined by the USP as those whose drug release characteristics of time course and/or location are chosen to accomplish therapeutic or convenience objectives not offered by conventional forms, whereas an extended-release (ER) dosage form allows a twofold reduction in dosing frequency or increase in patient compliance or therapeutic performance. It is interesting to note that the USP considers that the terms controlled-release, prolonged release and sustained release are interchangeable with extended release. From a biopharmaceutical perspective this is not strictly a concern.

Aulton details the methods of manufacture and the typical plasma concentration curves for these specialised dosage forms.

[pharmatron]

Forgot to mention - in practice care is needed when dispensing different forms to ensure the correct one e.g. Adizem-SR (given BD) / Adizem-XL (given OD). Similarly take care with Dilzem SR/XL etc... (Also, see advice in BNF re: prescribing diltiazem as a brand since diltiazem m/r capsules 120mg could mean Adizem, Angitil, Dilzem etc... and different preparations may not have the same clinical effect). Similarly, with nifedipine...Adalat LA/Adalat Retard and various other brands...

[Linnear]

Originally Posted by pharmatron

Forgot to mention - in practice care is needed when dispensing different forms to ensure the correct one e.g. Adizem-SR (given BD) / Adizem-XL (given OD). Similarly take care with Dilzem SR/XL etc... (Also, see advice in BNF re: prescribing diltiazem as a brand since diltiazem m/r capsules 120mg could mean Adizem, Angitil, Dilzem etc... and different preparations may not have the same clinical effect). Similarly, with nifedipine...Adalat LA/Adalat Retard and various other brands...

Then care needed when Dr's misprescribe.

XL as BD doses
SR as OD doses etc.

All good fun.

[Pharmanaut]

Originally Posted by Linnear

Then care needed when Dr's misprescribe.

XL as BD doses
SR as OD doses etc.

All good fun.

Check out the "Dictionary of medicines and devices", DM+D, this is the NHS standard classification that will be used by Primary Care. It will be the 'linqua franca' of the electronic prescription service.

If you look at Tramadol for example the brands are all attached to the same generic. (VMP is the generic and AMP is the brand)
If the GP software ignores the 'prescribe only by brand' flag on the VMP, and switches the product selection to the generic we will end up with scripts that you can't figure out if an XL or SR is required.

One of the things that will happen in a lot in the EPS.

Enjoy!

[ykw]

thanks for all the replies

[pharmacopola]

Originally Posted by pharmatron

These are similar but different dosage forms strictly speaking. Have a look in a Pharmaceutics textbook (e.g. Aulton) for details. From my notes the definitions are as follows:

oh that brings back memories of sleeping through formulation lectures! Good recap though - thanks!