Spray Drying as a Process for Microencapsulation and the Effect of Different Coating Polymers

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Abstract
Microencapsulation of theophylline drug particles was carried out by a spray drying technique using an aqueous system. Comparison was made between the use of a solution and a suspension feed. The spray dried products obtained from a suspension feed were encapsulated and have better flowability. Various polymers, hydroxypropylmethylcellulose acetate succinate (HPMCAS), hydroxypropylmethylcellulose (HPMC), methylcellulose (MC) and sodium carboxymethylcellulose (NaCMC) were studied to evaluate their spray-coating properties. The results showed that drug release from the coated products was dependent on the hydrophilicity of the polymer. NaCMC, which is more hydrophilic, gelled faster and retarded the drug release more effectively. HPMC and MC produced products with similar dissolution profiles and flow properties. Spray coating with HPMCAS was unsuccessful. The polymers also affect the size and cohesiveness of the products. Smaller size particles which are more cohesive cause agglomeration and delay release of the drug.