DRUG DELIVERY SYSTEMS UTILIZING LIQUID CRYSTAL STRUCTURES

摘要

Vitamin E TPGS/drug compositions and methods are provided which obviate theneed for surfactants or non-evaporated co-solventsbecause the active drug component is dissolved directly into Vitamin E TPGS toform a true molecular solution - not an emulsion or amicro-emulsion. The invention provides a slowly dissolving TPGS/drug matrixthat absorbs gastrointestinal fluid into the matrix at thedosage form/fluid interface where a gel-like liquid crystal is formed. Thisgel front forms a liquid crystal boundary where drug dissolutionis highest. At this liquid crystal/GI fluid boundary, a synchronization takesplace in which the rate of formation of liquid crystals equalsthe dissolution rate of liquid crystals at the water interface, thereby givingcontrolled order release of the drug into the GI tract. The rateof dissolution is also controlled by the geometry of the dosage form. Thesolid vitamin E TPGS/drug matrices of the invention can besolidified and compressed into tablets or filled into capsules, with otherexcipients, binders and/or fillers. The solid TPGS/drug solution ofthe invention also can be made into an immediate release liquid formulationupon addition of water, or into a controlled release systemsolid tablet by the use of impermeable or semi-permeable barriers or coatingssurrounding portions of the tablet.