Crystal structure of minoxidil at low temperature and polymorph prediction

J Pharm Sci. 2008 Feb;97(2):815-30. doi: 10.1002/jps.21015.


An experimental and theoretical investigation on crystal forms of the popular and ubiquitous pharmaceutical Minoxidil is presented here. A new crystallization method is presented for Minoxidil (6-(1-piperidinyl)-2,4-pyrimidinediamide 3-oxide) in ethanol-poly(ethylene glycol), yielding crystals with good quality. The crystal structure is determined at low temperature, with a final R value of 0.035, corresponding to space group P2(1) (monoclinic) with cell dimensions a = 9.357(1) A, b = 8.231(1) A, c = 12.931(2) A, and beta = 90.353(4) degrees . Theoretical calculations of the molecular structure of Minoxidil are set forward using empirical force fields and quantum-mechanical methods. A theoretical prediction for Minoxidil crystal structure shows many possible polymorphs. The predicted crystal structures are compared with X-ray experimental data obtained in our laboratory, and the experimental crystal form is found to be one of the lowest energy polymorphs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallization
  • Hydrogen Bonding
  • Minoxidil / chemistry*
  • Models, Molecular
  • Temperature
  • Thermodynamics


  • Minoxidil