Method for treating pain in trigeminal neuralgia

1. A method for alleviating and/or treating neuropathic trigeminal pain in a subject in need of such alleviation and/or treatment, the method comprising administering to a subject a compound of Formula (IIb)

wherein

Ar is phenyl which is unsubstituted or substituted with at least one halo group;

R 3 is CH 2 -Q, wherein Q is lower alkoxy containing 1-3 carbon atoms; and

R 1 is lower alkyl containing 1-3 carbon atoms, or a pharmaceutically acceptable salt thereof, in a dosage amount of about 50 mg/day to about 1 g/day.

2. The method of claim 1 , wherein the subject has neuropathic trigeminal pain and atypical facial pain.

3. The method of claim 1 wherein, in the compound of Formula (IIb), Ar is unsubstituted phenyl.

4. The method of claim 1 wherein, in the compound of Formula (IIb), halo is fluoro.

5. The method of claim 1 wherein, in the compound of Formula (IIb), R 3 is CH 2 -Q, wherein Q is alkoxy containing 1-3 carbon atoms, and Ar is unsubstituted phenyl.

6. The method of claim 1 , wherein the compound of Formula (IIb) is (R)-2-acetamido-N-benzyl-3-methoxypropionamide or a pharmaceutically acceptable salt thereof.

7. The method of claim 6 wherein the compound is substantially enantiopure.

8. The method of claim 1 , wherein the compound is administered at increasing daily doses until a predetermined daily dose is reached which is maintained during further treatment.

9. The method of claim 1 , wherein the compound is administered in no more than three doses per day.

10. The method of claim 6 , wherein the compound is administered in an amount resulting in a plasma concentration of the compound of 0.1 to 15 μg/ml (trough) and 5 to 18.5 μg/ml (peak).

11. The method of claim 1 , wherein the compound is administered orally or intravenously.

12. The method of claim 1 , further comprising administering to the subject a further active agent for alleviation and/or treatment of neuropathic trigeminal pain.

13. The method of claim 12 , wherein the compound of Formula (IIb) and the further active agent are administered in a single dose.

14. The method of claim 1 , wherein the subject is a mammal.

15. The method of claim 14 wherein the subject is a human.

16. The method of claim 1 , wherein the compound of Formula (IIb) or a pharmaceutically acceptable salt thereof is administered in a dosage amount of about 200 mg/day to about 1 g/day.

17. The method of claim 16 , wherein the compound of Formula (IIb) or a pharmaceutically acceptable salt thereof is administered in a dosage amount of about 200 mg/day to about 600 mg/day.

18. The method of claim 1 , wherein the compound of Formula (IIb) is (R)-2-acetamido-N-benzyl-3-methoxypropionamide in an oral dosage amount of about 50 mg/day to about 600 mg/day.

19. The method of claim 18 , wherein the dosage amount is about 200 mg/day to about 600 mg/day.

20. A method for alleviating and/or treating neuropathic trigeminal pain in a subject in need of such alleviation and/or treatment, the method comprising administering to the subject (R)-2-acetamido-N-benzyl-3-methoxypropionamide.