Controlled Release Systems

In a hydrophilic matrix system, a METHOCEL™ Premium CR cellulose ether or a POLYOX™ Water-Soluble Resin, NF Grade is uniformly incorporated throughout the tablet. Upon contact with water, it hydrates the outer tablet surface to form a gel layer. The rate of diffusion of drug out of the gel layer and the rate of tablet erosion control the overall dissolution rate and drug delivery.

METHOCEL™ Premium CR products and POLYOX™ Water-Soluble Resins, NF Grade are produced under controlled conditions that yield consistent properties and reproducible performance. They’re not subject to the range of variability sometimes encountered with polymers like guar, shellac, and other botanic extracts.

METHOCEL™ Premium CR cellulose ethers are specially engineered for pharmaceutical controlled release applications to deliver more consistent drug release performance. Using proprietary techniques, proven, trusted METHOCEL™ Premium CR cellulose ethers are manufactured for enhanced lot-to-lot consistency in chemical and physical properties that impact drug release performance, resulting in fast development of robust formulations.

Both METHOCEL™ Premium CR cellulose ethers and POLYOX™ Water-Soluble Resins, NF Grade have an excellent safety record — all needed data are available. Because they’re so widely used, techniques and equipment for formulation development and drug production are readily available.

When water-insoluble ETHOCEL™ Premium resin is combined with water-soluble METHOCEL™ Premium CR products, the water-soluble portions of the coating will dissolve in the gastrointestinal tract, leaving a non-continuous film of water-insoluble ethylcellulose. Controlling the relative concentrations of the coacervation processes and the ETHOCEL™ Premium polymer regulates the rate of drug diffusion from the inner tablet core. Diffusion is also controlled by the coating thickness.

ETHOCEL™ Premium polymers are used in film and bead coating for controlled release applications. They can also be used to coat drugs by a number of coacervation processes.

Dow/Colorcon Alliance
The alliance between Dow and Colorcon for the global marketing, sales, technical service and development, and distribution of Dow pharmaceutical excipient products for use in controlled release applications is our answer to the global pharmaceutical industry’s demand for faster development and more efficient production of drug ingredients.

Click here to see the specific METHOCEL™, ETHOCEL™ and POLYOX™ controlled release pharmaceutical products available through Colorcon. This alliance is being implemented by geography in 2007.

Dow Excipients in Controlled Release Applications

Application	Products Recommended	Typical Use Level	Advantages
Controlled Release Matrix Tablets	METHOCEL™ K100LV Premium CR, K4M Premium CR, K15M Premium CR, K100M Premium CR, E4M Premium CR, E10M Premium CR	20 – 55%1	METHOCEL™ K Premium CR has the fastest hydration rate of the METHOCEL™ family
	POLYOX™ WSR-205 NF, WSR-1105 NF, WSR N-12K NF, WSR N-60K NF, WSR-301 NF, WSR-303 NF, WSR Coagulant NF	20 – 90%	Molecular weight can be selected to tailor release profile
Controlled Release Coatings	ETHOCEL™ Standard Premium 4,7,10	3 – 20%1	Insoluble in water; provides good diffusion control membrane Mixing with METHOCEL™ Premium CR moderates diffusion
	ETHOCEL™ Premium blended with METHOCEL E5, E15 Premium	3 – 20%1	Insoluble in water; provides good diffusion control membrane Mixing with METHOCEL™ Premium CR moderates diffusion
Microencapsulation	ETHOCEL™ Standard 20, 45, 100 Premium	10 – 20%	Insoluble in water, can be coacervated (phase separated)

¹Use levels may vary with dosage form, size, and desired release rate

®™*Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow.