Pharmaceutical compositions comprising a poorly water soluble ionizable drug, a cationic species and a dispersion polymer are disclosed, together with a process for forming the compositions. The neutral form of the drug has (i) a solubility of less than 1 mg/ml, in aqueous solution at a pH between 6 and 7, (ii) a solubility of less than 20 mg/mL in a volatile organic solvent, and (iii) an acidic pKa value of greater than 5. At least 90 wt % of the drug in the solid dispersion being in a non-crystalline form. The drug, the cationic species, and the dispersion polymer constitute at least 80 wt % of the solid dispersion.