Microencapsulation using poly(L-lactic acid). I: Microcapsule properties affected by the preparative technique.
Microcapsules were prepared using a poly (L-lactic acid) (L = PLA), mol. wt. 43,200, by an emulsification and solvent evaporation technique. Phenobarbitone (PB) was used as a reference drug, (core to polymer ratio, 1:1). Both the o/w and w/o emulsion system were investigated in order to study microcapsule properties affected by the preparative technique. In the o/w system, dichloromethane (DCM) was used to dissolve L = PLA and PB and the resulting solution was dispersed in 1 per cent aqueous gelatin solution. Subsequent evaporation of the DCM resulted in the formation of microcapsules. PB was found to be poorly encapsulated within microcapsules from this o/w system. PB content in the microcapsules was found to improve using PB saturated aqueous gelatin solution as the continuum. In the w/o system, acetonitrile (AN) was used as a solvent for L-PLA and PB and light liquid paraffin (LLP), containing 2 per cent w/w Span 40, as the continuous phase. PB loading in the microcapsules was found to be very high from this w/o system. Microcapsules from the o/w system were very small compared to microcapsules obtained from the w/o system. The morphology of the microcapsules and the surface properties were found to be affected distinctly by the two techniques. Microcapsules from the o/w system showed a smooth and less porous surface, whereas a highly porous surface containing embedded PB crystals was found in the microcapsules from the w/o system.
Jalil
R
R
Chelsea Department of Pharmacy, King's College London.
Nixon
J R
JR
D002214:Capsules / Q000138:chemical synthesis*; D004339:Drug Compounding / Q000379:methods*; D007773:Lactates; D019344:Lactic Acid; D008855:Microscopy, Electron, Scanning; D010634:Phenobarbital / Q000008:administration & dosage*; D011091:Polyesters; D011108:Polymers; D013499:Surface Properties
D002214:Capsules; D007773:Lactates; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D010634:Phenobarbital