Oral osmotic system
An oral osmotic system (also called OROS , osmotic release oral system ) is a dosage form for the long-lasting , uniform release of an active ingredient . The release is controlled by the osmotic pressure .
OROS is a registered name of the Alza Corporation .
construction
With simple OROS, a strongly osmotically active auxiliary substance (e.g. sodium chloride or mannitol ) is mixed with the active substance and pressed. The resulting tablet is coated with a semipermeable film. This usually consists of ethylene vinyl acetate or cellulose acetate . Since the film is impermeable to the active substance, a laser drills a 100-250 nm hole in the film through which the active substance can later escape. The release in the gastrointestinal tract occurs when water flows into the interior of the tablet due to the osmotic pressure, dissolves the active ingredient and pushes it out through the hole. The release rate can thus be kept the same over a longer period of time.
Push-pull OROS
Push-Pull-OROS is a two-chamber system. One chamber contains the active substance, the other the osmotically active auxiliary substance. Both chambers are separated by a flexible partition. Again, the entire tablet is covered by a semipermeable film, but the hole must be on the side on which the active ingredient chamber is located. In production, this is ensured by the fact that the two tablet sides are colored differently so that the laser can recognize on which side it has to drill.
Here, too, water must flow from the outside to the inside for the release. However, the loosened active ingredient is now pushed outwards by the increase in volume of the second chamber and the resulting arched partition. This system ensures that only the active ingredient and no excipients are released.
A special form of the push-pull OROS does not contain osmotically active auxiliary substances in the second chamber, but swellable substances, mostly polyethylene glycol (e.g. PEG 200,000). These also show an increase in volume due to water retention. Mixtures of swellable and osmotically active auxiliaries are also possible.
Liquid OROS
Liquid-OROS (L-OROS for short) is also a two-chamber system. Here, however, the active ingredient is dissolved in a non-aqueous solvent. So that the active ingredient solution is not released before it is taken, the tablet must also be coated with a water-soluble film.
All forms of OROS retain their external shape as they pass through the gastrointestinal tract and are excreted undigested.
Problems
There are mainly problems with the choice of the right auxiliary material. This must generate a high osmotic pressure and maintain it during the entire release.
The dangers of supposedly harmless auxiliary materials were also not recognized at the beginning. Several complications with potassium chloride have been observed. If it hits the stomach wall in a saturated solution, as can happen with OROS, it can lead to perforation and consequently death. Therefore, nowadays, sodium chloride or mannitol are usually found as auxiliary substances.
Examples
Application examples of OROS are the Jurnista and Concerta prolonged-release tablets from Janssen-Cilag-GmbH. The former contains hydromorphone hydrochloride as a pain reliever. The second preparation is available for the treatment of ADHD with the active ingredient methylphenidate hydrochloride .
Individual evidence
- ^ Rudolf Voigt: Pharmaceutical Technology. 11th edition, 2010, Deutscher Apotheker Verlag, ISBN 978-376-925003-9
- ↑ L-OROS SOFTCAPTM for Controlled Release of Non-Aqueous Liquid Formulations
- ↑ With Jurnista® pain relief "around the clock" ( page can no longer be accessed , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ^ Concerta: Methylphenidate OROS in ADHD
