Controlled release formulations having rapid onset and rapid decline of effective plasma drug concentrations

1. An oral controlled release formulation which provides a rapid onset of therapeutic effect and a rapid drop in plasma concentration after a prolonged period of therapeutic effect, comprising

a plurality of substrates comprising a portion of an effective dose of methylphenidate hydrochloride in immediate release form,

a hydrophobic material comprising an acrylic polymer, coated onto the surface of said substrates in an amount sufficient to retard the release of said drug,

an enteric coating applied over said hydrophobic coating in an amount sufficient to substantially delay the release of said drug from said substrate until after said formulation passes through the stomach, wherein said enteric coating is derived from an aqueous dispersion comprising an acrylic/methacrylic copolymer, a plasticizer and a glidant,

the formulation further comprising the remaining portion of said methylphenidate hydrochloride in immediate release form, and

wherein the formulation provides a time to maximum plasma concentration of said methylphenidate hydrochloride at about 0.5 to about 4 hours after oral administration.

2. The formulation of claim 1 , wherein said remaining portion of said methylphenidate or a pharmaceutically acceptable salt thereof is applied to said substrates over said enteric coating.

3. The formulation of claim 1 , wherein a unit dose comprises said plurality of substrates contained within a gelatin capsule, and said remaining portion of said methylphenidate or pharmaceutically acceptable salt thereof is contained within said gelatin capsule in a form selected from the group consisting of an immediate release powder, an immediate release granulate, immediate release matrix spheroids, immediate release beads, and as a coating applied onto the surface of said enteric coated substrates.

4. The formulation of claim 1 , wherein said hydrophobic material comprises a plasticized aqueous dispersion of an acrylic polymer which is sprayed onto the surface of said substrates.

5. The formulation of claim 4 , wherein said substrates are subjected to oven curing at a temperature above the glass transition temperature of the plasticized acrylic polymer at a temperature from about 40 to about 50°C. for a time period of at least about 12 hours prior to the application of said enteric coating.

6. The formulation of claim 1 , which provides a peak plasma concentration of the methylphenidate or a pharmaceutically acceptable salt thereof which is from about 1.0 to about 2.0 times the plasma concentration of the methylphenidate or a pharmaceutically acceptable salt thereof provided by the formulation at about 9 hours after oral administration.

7. The formulation of claim 6 , wherein the duration of effect provided by the methylphenidate or a pharmaceutically acceptable salt thereof contained in the formulation falls below effective plasma concentrations at about 8 to about 12 hours after oral administration.

8. The formulation of claim 7 , wherein the oral dosage form provides a time to maximum plasma concentration at about 0.5 to about 2 hours after oral administration.

9. The formulation of claim 6 , wherein the peak plasma concentration is from about 1.0 to about 1.7 times the plasma concentration of methylphenidate or a pharmaceutically acceptable salt thereof provided by the formulation at about 9 hours after oral administration.

10. The formulation of claim 6 , wherein the duration of effect provided by the methylphenidate or a pharmaceutically acceptable salt thereof contained in the oral dosage form falls below effective plasma concentrations at about 8 to about 10 hours after oral administration.

11. The formulation of claim 10 , which provides a “square wave” plasma profile.

12. The formulation of claim 10 , which provides an in-vitro dissolution as follows:

Time

% Methylphenidate

(hours)

Dissolved

0.25

0–45%

1

5–50%

4

40–90% 

8

NLT 60%

12

NLT 80%.