Pharmaceutical formulation comprising one or more fumaric acid esters in an erosion matrix

1. A method of preparing a pharmaceutical formulation in the form of an erosion matrix tablet comprising:

a) dissolving or suspending a rate-controlling agent in the form of a polymeric matrix material in water to produce an aqueous suspension;

b) spraying the aqueous suspension on granules of dimethyl fumarate for a period of time sufficient to obtain a uniform coating thereon;

c) drying the coated granules;

d) sieving or milling the coated granules;

e) blending the coated granules with a pharmaceutically acceptable excipient or additive, and pressing the blend to produce a tablet core; and

f) film and enteric coating the tablet core to produce the erosion matrix tablet;

wherein steps (a)-(f) are performed at a temperature such that a product temperature does not exceed 45° C.;

wherein the tablet core comprises:

i) 30% to 60% by weight dimethyl fumarate;

ii) 3% to 6% by weight hydroxypropyl cellulose, as the rate-controlling agent; and

iii) 35% to 65% by weight lactose, as the pharmaceutically acceptable excipient or additive; and

wherein erosion of said erosion matrix permits controlled or sustained release of the dimethyl fumarate.

2. The method of claim 1 , wherein the tablet core further comprises:

0.15% to 0.7% by weight magnesium stearate; and

0.05% to 0.25% by weight silicon dioxide.

3. The method of claim 2 , wherein the enteric coating is applied at a level of 1.5% to 3.5% by weight of the tablet core.

4. The method according to claim 1 , wherein steps (a)-(f) are performed at a temperature such that the product temperature does not exceed 35° C.

5. The method according to claim 1 , wherein the tablet core comprises:

i) 40% to 55% by weight dimethyl fumarate;

ii) 4% to 6% by weight hydroxypropyl cellulose;

iii) 35% to 55% by weight lactose.

6. The method according to claim 3 , wherein erosion of said erosion matrix results in release of the dimethyl fumarate, when subjected to an in vitro dissolution test employing 0.1N hydrochloric acid as dissolution medium during the first 2 hours of the test and then 0.05 M phosphate buffer pH 6.8 as dissolution medium, as follows:

within the first 2 hours after start of the test from 0% w/w to less than 10% w/w of the dimethyl fumarate contained in the formulation is released;

within the first 3 hours after start of the test from 20% w/w to 75 w/w of the dimethyl fumarate contained in the formulation is released;

within the first 4 hours after start of the test from 50% w/w to 98% w/w of the dimethyl fumarate contained in the formulation is released; and

within the first 5 hours after start of the test from 70% w/w to 100% w/w of the total amount of the dimethyl fumarate contained in the formulation is released.