Abstract
When short plasma half-life drugs act only briefly, they require frequent or continuous administration. We report the engineering of a non-invasive oral drug delivery system for long-term, continuous administration of these drugs. Their non-invasive, long-term, continuous administration at daily doses exceeding 100 mg has, for many years, been considered an insurmountable challenge. We show that over 1200 mg/day of 4:1 levodopa-carbidopa (LD-CD) can be non-invasively and continuously extruded when formulated as a semisolid paste, loaded with 63%w/w of the solid drugs. The drug delivery system comprises a reusable orthodontic retainer with a co-molded pocket into which the patient inserts after each meal a new 1 mL propellant-driven, prefilled, disposable, drug delivery extruder. The paste is delivered to the lingual side of the teeth where it is mixed with saliva and swallowed. As reported elsewhere, a 15-day, 16 patient open label clinical trial of the drug delivery system continuously extruding LD-CD paste significantly reduces the variability of the plasma LD concentration and alleviates symptoms of advanced Parkinson's disease (PD) as compared to LD-CD tablets.