MODIFIED RELEASE DRUG POWDER COMPOSITION COMPRISING GASTRO-RETENTIVE RAFT FORMING SYSTEMS HAVING TRIGGER PULSE DRUG RELEASE

An orally administrable drug powder composition which forms a gastro-retentive RAFT having at least two trigger pulses is provided. The composition contains, at a minimum, (a) at least one drug in an immediate release pulse release form; (b) at least one drug in a delayed trigger release form; (c) at least one non-toxic gas generating agent and (d) a RAFT system, wherein following oral ingestion, the composition provides a self-assembling gastro-retentive RAFT having entrapped therein, the at least one drug of (a) and (b) and the gas generated in situ by the non-toxic gas generating agent, thereby providing a floating gastro-retentive RAFT having a dual pulse system wherein at least the second pulse is a trigger pulse and which retains the at least one drug in the stomach for at least about 3 hours, provided that the composition does not include a gamma hydroxybutyrate and its salts, hydrates, tautomers, or solvates, or complexes thereof.