crystalline form of compound pirmido [6,1-a] isoquinolin-4-one

A crystalline polymorph (I) of (N- {2 - [(2E) -2- (mesitylimino) -9,10-dimethoxy-4-oxo-6,7-dihydro-2H-pyrimido [6,1-a] - isoquinolin-3 (4H) -yl] ethyl} urea) having a diffraction pattern in X-ray powder comprising characteristic peaks, in terms of 2θ, at 10,1o and 12.9 °.