2-(3,4-dimethylphenyl)-4-{[2-hydroxy-3′-(1h-tetrazol-5-yl)biphenyl-3-yl]-hydrazono}-5-methyl-2,4-dihydropyrazol-3-one choline

1. 2-(3,4-dimethylphenyl)-4-{[2-hydroxy-3′-(1H-tetrazol-5-yl)biphenyl-3-yl]-hydrazono}-5-methyl-2,4-dihydropyrazol-3-one choline.

2. A pharmaceutical composition comprising 2-(3,4-dimethylphenyl)-4-{[2-hydroxy-3′-(1H-tetrazol-5-yl)biphenyl-3-yl]-hydrazono}-5-methyl-2,4-dihydropyrazol-3-one choline and a pharmaceutically acceptable carrier or diluent.

3. A method of treating thrombocytopenia in a mammal in need thereof which comprises administering to such mammal a therapeutically effective amount of a compound as described in claim 1 .

4. A method as claimed in claim 3 , wherein the mammal is a human.

5. The method of claim 3 wherein the compound is administered orally.

6. The method of claim 3 wherein the compound is administered parenterally.

7. A process for preparing a pharmaceutical composition containing a pharmaceutically acceptable carrier or diluent and an effective amount of a compound as described in claim 1 , which process comprises bringing the compound described in claim 1 into association with the pharmaceutically acceptable carrier or diluent.

8. The method of claim 3 further comprising co-administering a therapeutically effective amount of an agent selected from the group consisting of: a colony stimulating factor, cytokine, chemokine, interleukin or cytokine receptor agonist or antagonists, soluble receptors, receptor agonists and antagonist antibodies.

9. The method of claim 8 wherein the agent is selected from the group consisting of: G-CSF, GM-CSF, TPO, M-CSF, EPO, Gro-beta, IL-11, SCF, FLT3 ligand, LIF, IL-3, IL-6, IL-1, Progenipoietin, NESP, SD-01, IL-8, and IL-5.

10. A method of claim 3 wherein said thrombocytopenia is due to myelosuppression caused by chemotherapy or radiation therapy.

11. A method of claim 3 wherein said thrombocytopenia is due to an organ transplant.

12. A method of claim 3 wherein said thrombocytopenia is due to bone marrow, stem cell, or liver transplant.

13. A method of claim 3 wherein said thrombocytopenia is due to idiopathic thrombocytopenia purpura (ITP).

14. A method of claim 3 wherein said thrombocytopenia is due to myelodysplastic syndromes (MDS), aplastic anemia or leukemia.

15. A method of claim 3 wherein said thrombocytopenia is due to viral, fungal, microbial or parasitic infection.

16. A method of claim 3 wherein said thrombocytopenia is due to liver dysfunction.

17. A method of claim 3 wherein said thrombocytopenia is due to surgical procedures.

18. A method of claim 3 wherein said thrombocytopenia is drug—induced.

19. A process for preparing the compound of claim 1 , which process comprises:

i) dissolving 2-(3,4-dimethylphenyl)-4-{[2-hydroxy-3′-(1H-tetrazol-5-yl)biphenyl-3-yl]-hydrazono}-5-methyl-2,4-dihydropyrazol-3-one in an organic solvent or solvents, to form a solution;

ii) adding one or more equivalents of choline hydroxide to the solution; and

iii) isolating the prepared compound.

20. The process of claim 19 wherein the solution contains a mixture of ethyl acetate and ethanol.

21. The process of claim 19 wherein the solution contains tetrahydrofuran.