Granules drug release dependent

Hypromellose acetate succinate may be used alone or in combination with other soluble or insoluble binders in the preparation of granules with sustained drug-release properties the release rate is pH-dependent. 

Hypromellose phthalate may be used alone or in combination with other soluble or insoluble binders in the preparation of granules with sustained drug-release properties the release rate is pH-dependent. Since hypromellose phthalate is tasteless and insoluble in saliva, it can also be used as a coating to mask the unpleasant taste of some tablet formulations. Hypromellose phthalate has also been co-precipitated with a poorly soluble drug to improve dissolution characteristics. 

The principal mechanism for the deactivation of released catecholamines is, however, not enzymatic destmction but reuptake into the nerve ending. The presynaptic membrane contains an amine pump—a saturable, high-affinity, Na" -dependent active-transport system that requires energy for its function. The recycled neurotransmitter is capable of being released again, as experiments with radiolabelled [ H]NE have shown, and can be incorporated into chromaffin granules as well. Many drugs interfere with neurotransmitter reuptake and metabolism, as discussed in subsequent sections. 

Enteric acrylic polymers were used as binders in high-shear wet granulation in order to target the colon and prevent drug from being released in the small intestine. Twenty percent ethanolic solutions of each of the following pH-dependent methacrylate... 

Rapid release granulation is expected to benefit the class of compound where absorption is highly dependent on the dissolution of the drugs in the gastrointestinal tract, termed as Class II compounds under the Biopharmaceutics Classification Scheme (Table 1). 

Dry granulation via slugging and roller compaction of hydroxypropyhnethyl-cellulose with naproxen, nifedipine, or carbazepine resulted in improvement of their dissolution profiles. The mechanism for dissolution enhancement was believed to be a microenviromnent hydroxypropyhnethylcellulose surfactant effect facilitated by plaeing the hydroxypropyhnethylcellulose in close proximity to the drug as simple mixing did not result in enhanced dissolution (40). Another example was the use of polyethylene 40 hydrogenated castor oil to improve the in vitro release of hydrochlorothiazide (41). The release was dependent on the concentration of surface active... 

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