A pharmaceutical answer to nonadherence: Once weekly oral memantine for Alzheimer's disease.

Adherence to medication regimens is a major barrier to effective treatment in many disease areas, notably in dementia which causes cognitive impairment that reduces patients' awareness of non-adherence and their ability to manage medication. The development of oral dosage forms that can be infrequently dosed, and therefore improve adherence rate and facilitate direct observed therapy, has been a goal for decades. We describe the first demonstration of an oral formulation that achieves >7-day gastric retention and sustained pharmacokinetics in the challenging dog model. Gastric retention requires physical resistance of the dosage form to gastric emptying forces, which are known to be stronger in dogs than in humans, making successful gastric retention in dogs a stringent test for predicting human translatability. This formulation of memantine hydrochloride is the first oral dosage form that achieves multi-day drug release with near zero-order kinetics and efficient delivery. In the dog model, relative memantine bioavailability approaches 100% with sustained plasma levels of memantine over seven days and profiles that can be tuned by varying components of the formulation. A single gastric resident dosage form achieves an AUC equivalent to 7 daily treatments with the marketed daily capsule, with a Cmax that is no higher than the daily product. PK modeling predicts that the gastroretentive formulation will maintain therapeutic blood levels in humans when administered once weekly. The formulation methodology presented here is applicable to many water soluble drugs and may enable the development of long-acting oral therapies for a wide variety of conditions.

Preclinical development and clinical translation of a PSMA-targeted docetaxel nanoparticle with a differentiated pharmacological profile.

We describe the development and clinical translation of a targeted polymeric nanoparticle (TNP) containing the chemotherapeutic docetaxel (DTXL) for the treatment of patients with solid tumors. DTXL-TNP is targeted to prostate-specific membrane antigen, a clinically validated tumor antigen expressed on prostate cancer cells and on the neovasculature of most nonprostate solid tumors. DTXL-TNP was developed from a combinatorial library of more than 100 TNP formulations varying with respect to particle size, targeting ligand density, surface hydrophilicity, drug loading, and drug release properties. Pharmacokinetic and tissue distribution studies in rats showed that the NPs had a blood circulation half-life of about 20 hours and minimal liver accumulation. In tumor-bearing mice, DTXL-TNP exhibited markedly enhanced tumor accumulation at 12 hours and prolonged tumor growth suppression compared to a solvent-based DTXL formulation (sb-DTXL). In tumor-bearing mice, rats, and nonhuman primates, DTXL-TNP displayed pharmacokinetic characteristics consistent with prolonged circulation of NPs in the vascular compartment and controlled release of DTXL, with total DTXL plasma concentrations remaining at least 100-fold higher than sb-DTXL for more than 24 hours. Finally, initial clinical data in patients with advanced solid tumors indicated that DTXL-TNP displays a pharmacological profile differentiated from sb-DTXL, including pharmacokinetics characteristics consistent with preclinical data and cases of tumor shrinkage at doses below the sb-DTXL dose typically used in the clinic.