Composition and method for treating neurological disease

A dosage form suitable for once-daily oral administration to a human subject consisting of

• (i) 50 mg to 500 mg of a drug selected from the group consisting of amantadine and pharmaceutically acceptable salts thereof, and (ii) at least one excipient, wherein at least 50% of the drug in the dosage form is in an extended release form, and wherein the dosage form provides a mean change in amantadine plasma concentration as a function of time (dC/dT) that is less than 40% of the dC/dT provided by the same quantity of the drug in an immediate release form, wherein the dC/dT values are measured in a single dose human pharmacokinetic study over the time period between administration and Tmax of the immediate release form.

A dosage form suitable for once-daily oral administration to a human subject consisting of

• (i) 50 mg to 500 mg of a drug selected from the group consisting of amantadine and pharmaceutically acceptable salts thereof, and (ii) at least one excipient, wherein at least 50% of the drug in the dosage form is in an extended release form, and wherein the dosage form provides a mean change in amantadine plasma concentration as a function of time (dC/dT) that is less than 40% of the dC/dT provided by the same quantity of the drug in an immediate release form, wherein the dC/dT of the dosage form is measured in a single dose human pharmacokinetic study over the time period between 2 hours and 4 hours after administration and the dC/dT provided by the same quantity of the drug in an immediate release form is measured in a single dose human pharmacokinetic study over the time period between administration and Tmax of the immediate release form.