Types of Modified-Release Dosage
- Mechanism that delivers a drug with a delay after administration (delayed-release dosage)
- Mechanism that delivers a drug for a prolonged period of time (extended-release dosage)
- Mechanism that delivers a drug to a specific target in the body (targeted-release dosage)
- Sustained-release dosage forms maintain a constant drug concentration for a specific period of time with minimum side effects
- Extended-release dosage consists of sustained-release (SR) or controlled-release (CR) dosage
Abbreviations and Considerations
- No industry standard for abbreviations, leading to potential confusion and misreading
- Clear handwriting is necessary, and putting the meaning in parentheses is advisable for drugs with multiple formulations
- Examples of abbreviations include XR (extended-release), XL (extended-release), and SR (sustained-release)
- Abbreviations should be used with caution to avoid prescribing errors
- Lack of standardization in abbreviations can be a challenge in the medical field
Methods of Modified-Release Formulation
- Most time-release drugs are formulated with the active ingredient embedded in an insoluble matrix
- Some sustained-release formulations involve drug dissolution into the matrix, causing it to swell and form a gel
- Micro-encapsulation is a technology used to produce complex dissolution profiles for sustained-release drugs
- Considerations for sustained-release formulation include pharmacological activity, absorption, and biological half-life of the drug
- Therapeutic index and dose dumping are factors to consider when developing time-release drugs
Diffusion and Dissolution Systems
- Diffusion systems rate release is dependent on the rate at which the drug dissolves through a barrier, usually a polymer
- Reservoir devices coat the drug with polymers to achieve sustained-release effects
- Matrix devices form a matrix where the drug is dissolved or dispersed
- Matrix devices cannot achieve zero-order release, but higher molecular weight molecules can be used
- Factors such as food can affect the release rate of diffusion matrix devices
- Dissolution systems require the drug to dissolve or disperse within a matrix
- Reservoir devices have sustained-release effects when the polymer does not dissolve and allows drug release through diffusion
- Matrix devices release the drug by undergoing diffusion, with the rate of dissolution determining the release rate
- Matrix devices are easier to produce and protect from changes in the gastrointestinal tract, but release rate can be affected by factors like food.
Other Modified-Release Systems
- Osmotic controlled-release oral delivery systems (OROS) use a semi-permeable outer membrane and small laser-drilled holes to release the drug.
- Ion-exchange resins are cross-linked water-insoluble polymers that contain ionisable functional groups.
- Floating systems float on gastric fluids due to their low density.
- Bio-adhesive systems stick to mucus and are favorable for mouth-based interactions.
- Matrix systems use a mixture of materials with the drug to slow down release.
Modified-release dosage Data Sources
| Reference | URL |
|---|---|
| Glossary | https://www.alternix.com/blogs/glossary-of-terms/modified-release-dosage |
| Wikipedia | http://en.wikipedia.org/wiki/Modified-release_dosage |
| Wikidata | https://www.wikidata.org/wiki/Q5165929 |
| Knowledge Graph | https://www.google.com/search?kgmid=/m/0277b_c |
