Phenylpropanolamine HCl Microcapsules: Preparation and release studies

Microcapsules of phenylpropanolamine HCL were prepared by three techniques, viz. coacervation-phase separation, air suspension, and pan coating, using different polymers and/or waxes as wall-forming materials.

Formulations showed reasonable dissolution behaviour, viz. microcapsules prepared by air suspension with polymer level of 20% polyvinyl acetate copolymer (PVAC) associated with 40% carnauba wax (II) and microcapsules prepared by pan coating with polymer level of 25% Rodopace^R (III), were evaluated for their absorption rates by demonstrating their toxicities compared to pure grug (I) by the LD₅₀ method. Toxicity assessment showed close agreement between the increase in lethal dose and the decrease in dissolution rate and revealed that Formula III has more prolonged action than Formulae II and I.