Solid Dispersion Formulation
Also known as: solid solution, amorphous dispersion, polymer-based formulation
Solid dispersion is a formulation technique where a poorly soluble drug is molecularly dispersed in a hydrophilic polymer matrix, improving aqueous solubility and bioavailability. Introduced by Chiou and Riegelman in 1971, solid dispersions remain a key strategy for overcoming solubility-limited absorption.
Key highlights
- Dramatically improves dissolution: amorphous drug dispersed in a hydrophilic polymer matrix dissolves far faster than crystalline drug
- Established technology: hot-melt extrusion and spray drying are scalable, GMP-compatible manufacturing platforms
- Excipient flexibility: wide range of approved polymers (HPMC, PVP, Eudragit) and plasticizers available
- Multiple approved products: Kaletra, Zelboraf, and others demonstrate regulatory and clinical viability
- Suitable for thermolabile drugs (spray drying): avoids high-temperature processing required for hot-melt extrusion
Intuition
This section is available to Pro members. Upgrade to Pro
How it works
This section is available to Pro members. Upgrade to Pro
When to use it
Use solid dispersion formulation when improving dissolution rate and oral bioavailability of Biopharmaceutics Classification System (BCS) Class II or IV drugs with poor aqueous solubility — particularly when conventional approaches (particle size reduction, salt formation) are insufficient to achieve therapeutic drug levels.
Strengths & limitations
- Dramatically improves dissolution: amorphous drug dispersed in a hydrophilic polymer matrix dissolves far faster than crystalline drug
- Established technology: hot-melt extrusion and spray drying are scalable, GMP-compatible manufacturing platforms
- Excipient flexibility: wide range of approved polymers (HPMC, PVP, Eudragit) and plasticizers available
- Multiple approved products: Kaletra, Zelboraf, and others demonstrate regulatory and clinical viability
- Suitable for thermolabile drugs (spray drying): avoids high-temperature processing required for hot-melt extrusion
- Physical instability: amorphous drug can recrystallize on storage, reverting to poor-solubility crystalline form
- Moisture sensitivity: hygroscopic polymers absorb water, plasticizing the matrix and promoting crystallization
- Drug loading limits: high drug loads (>40%) often compromise stability; polymer-rich formulations increase tablet size
- Manufacturing complexity: hot-melt extrusion requires careful temperature control; spray drying needs solvent handling infrastructure
- Supersaturation maintenance: improved dissolution in vitro does not always translate to improved in vivo absorption without precipitation inhibitors
Sources
- 1.Chiou, W. L., Riegelman, S. (1971). Pharmaceutical applications of solid dispersions. Journal of Pharmaceutical Sciences, 60(9), 1281-1302.
- 2.Vasconcelos, T., Sarmento, B., & Costa, P. (2007). Solid dispersions as strategy to improve oral bioavailability of poorly water soluble drugs. Drug Discovery Today, 12(23-24), 1068-1075.
You have read it. What now?
Cite this page
ScholarGate. (2026, June 3). Solid Dispersion. ScholarGate. https://scholargate.app/pharmacology/solid-dispersion