Process for the preparation of roflumilast

1. A method for the treatment of chronic obstructive pulmonary disease, comprising: administering to a patient suffering from chronic obstructive pulmonary disease N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide and a therapeutically effective amount of roflumilast.

2. The method of claim 1 , wherein said roflumilast has a purity of greater than or equal to 99% by weight.

3. The method of claim 2 , wherein said roflumilast has a purity of greater than or equal to 99.8% by weight.

4. The method of claim 1 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.1% by weight.

5. The method of claim 4 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.05% by weight.

6. A method for the treatment of chronic obstructive pulmonary disease, comprising: administering to a patient suffering from chronic obstructive pulmonary disease, a therapeutically effective amount of roflumilast having a purity of greater than or equal to 99% by weight, and N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide present (relative to roflumilast) in an amount greater than zero and less than 0.1% by weight.

7. The method of claim 6 wherein said roflumilast has a purity of greater than or equal to 99.8% by weight.

8. The method of claim 6 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.05% by weight.

9. A method for the treatment of chronic obstructive pulmonary disease, comprising: administering to a patient suffering from chronic obstructive pulmonary disease a therapeutically effective amount of a pharmaceutical composition, comprising: roflumilast; N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide; and pharmaceutically acceptable auxiliaries and/or excipients.

10. The method of claim 9 , wherein said roflumilast has a purity of greater than or equal to 99% by weight.

11. The method of claim 10 , wherein said roflumilast has a purity of greater than or equal to 99.8% by weight.

12. The method of claim 9 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.1% by weight.

13. The method of claim 12 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.05% by weight.

14. A method for the treatment of chronic obstructive pulmonary disease, comprising: administering to a patient suffering from chronic obstructive pulmonary disease, a therapeutically effective amount of a pharmaceutical composition, comprising: roflumilast having a purity of greater than or equal to 99% by weight; N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide present (relative to roflumilast) in an amount greater than zero and less than 0.1% by weight; and pharmaceutically acceptable auxiliaries and/or excipients.

15. The method of claim 14 , wherein said roflumilast has a purity of greater than or equal to 99.8% by weight.

16. The method of claim 14 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.05% by weight.

17. A method for the treatment of chronic obstructive pulmonary disease, comprising: administering to a patient suffering from chronic obstructive pulmonary disease, a therapeutically effective amount of a pharmaceutical dosage form, comprising: roflumilast having a purity of greater than or equal to 99% by weight; N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide present (relative to roflumilast) in an amount greater than zero and less than 0.1% by weight; and pharmaceutically acceptable auxiliaries and/or excipients.

18. The method of claim 17 , wherein said roflumilast has a purity of greater than or equal to 99.8% by weight.

19. The method of claim 17 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.05% by weight.

20. The method of claim 17 , wherein said pharmaceutical dosage form is selected from the group consisting of tablets, coated tablets, capsules, caplets, suppositories, emulsions, suspensions, gels and solutions.

21. The method of claim 17 , wherein said pharmaceutical dosage form includes from between 0.1% and 95% roflumilast.

22. The method of claim 17 , wherein the pharmaceutical dosage form is an oral dosage form.

23. The method of claim 17 , wherein the pharmaceutical dosage form contains from 0.05 mg to 2.5 mg of roflumilast.

24. The method of claim 23 , wherein the pharmaceutical dosage form contains from 0.1 to 0.5 mg of roflumilast.

25. The method of claim 24 , wherein the pharmaceutical dosage form contains 0.25 mg of roflumilast.

26. The method of claim 24 , wherein the pharmaceutical dosage form contains 0.5 mg of roflumilast.

27. A method for the treatment of chronic obstructive pulmonary disease, comprising: administering to a patient suffering from chronic obstructive pulmonary disease, a therapeutically effective amount of a pharmaceutical tablet, comprising: 0.5 mg of roflumilast having a purity of greater than or equal to 99% by weight; N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide present (relative to roflumilast) in an amount less than 0.1% by weight; and pharmaceutically acceptable auxiliaries and/or excipients.

28. The method of claim 27 , wherein said roflumilast has a purity of greater than or equal to 99.8% by weight.

29. The method of claim 27 , wherein said N-(3,5-dichloropyrid-4-yl)-3-cyclopropylmethoxy-4-hydroxybenzamide is present (relative to roflumilast) in an amount greater than zero and less than 0.05% by weight.