Cellulose hydroxypropylmethylcellulose acetate

Ketoprofen (SIMS), hydroxypropylmethylcellulose E5 (HPMC, t =2%, 5mPas, Dow Chemical), glyceryl monostearate (Precirol, Gattefosse), Eudragit E 30 D (Rhom Pharma), Polyethylene glycol 400 (PEG 400, Merck) and cellulose acetate phthalate (CAP, Ambrochim) were used directly without any prior purification. 

The salt form of the polymer may also play a role in determining the performance of the formulation. Kane et al. [32] found that cellulose acetate phthalate was more effective than cellulose acetate trimellitate in controlling the dissolution of sulfothiazole-sodium tablets with cellulose acetate. The enteric properties of hydroxypropylmethylcellulose phthalate (HPMCP) were found to depend on the solubility of the drug that was coated. 

The core may be a water-soluble polymer, an inert salt or, as in the case of metoprolol fumarate, the drug itself, whose saturated solution has an osmotic pressure of 32.5 atm. The osmotic tablet of nifedipine is described in detail in Fig. 8.38, which shows the semipermeable cellulose acetate coating, the swellable hydrogel layer of polyoxyethylene glycol and hydroxypropylmethylcellulose (HPMC) and the dmg chamber containing nifedipine in HPMC and PEG. 

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