RELEASE RATE PROFILES OF THEOPHYLLINE AND INSULIN FROM STABLE MULTIPLE W O/W EMULSIONS/

Stable multiple w/o/w emulsions have been prepared using various Pluro nic F127:PAA complexes in the internal aqueous phases of these emulsio ns. Theophylline and I-125-insulin were incorporated into the internal aqueous phases of these stable multiple emulsions and their release r ates studied. The release rates of theophylline from these emulsions w ere found to be related to the droplet sizes of the emulsions which in turn was dependent on the particle sizes of the Pluronic:PAA complex in the internal aqueous phase, and the type of lipophilic surfactant i n the oil phase, The use of surfactants with different HLB values in t he external aqueous phase did not affect the entrapment efficiency of these emulsions. The release rate of I-125-insulin from one of these e mulsions was significantly slower than from I-125-insulin solution. Th e release pattern of I-125-insulin from this same emulsion after stora ge for three days was not significantly different from the newly-prepa red emulsion. The results indicate that it is possible to formulate dr ugs such as theophylline and insulin in multiple w/o/w emulsions where we have found them to be stable and could thus be formulated for rapi d onset of action or as sustained drug delivery system, depending on t he choice of Pluronic:PAA complex in the internal aqueous phase and th e type of lipophilic surfactant in the oil phase. (C) 1997 Elsevier Sc ience Ireland Ltd.