TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The supercritical or liquefied gas contains a gas selected from carbon dioxide, nitrous oxide, argon and/or nitrogen.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The supercritical or liquefied gas contains a gas selected from ethane, ethylene propane, cyclopropane, propylene, and butane.    TECHNOLOGY FOCUS - PHARMACEUTICALS - Preferred Method: The co-crystallization medium is saturated with both the active component and the co-builder. The solids in the co-crystallization medium are subjected to stirring, recirculation, gas injection, boiling, shaking and/or other methods of mechanical action. The active component ( not greater than 5%) is in a dissolved state during contacting and transforming steps. The co-builder ( not greater than 10%) is in a dissolved state during contacting and transforming steps. The supercritical or liquefied gas has a pressure of 70-500 bar, and a temperature of 30-100 degrees C. The solid particles of the active component that are employed in contacting step have a mass weighted average diameter of less than 50 mu m. The solid particles of the co-builder that are employed in contacting step have a mass weighted average diameter of less than 50 mu m. The active component employed in contacting step has a water solubility at 37 degrees C of less than 5 mg/l. The co-crystals contain the active component (20-80 wt.%) and the co-builder (80-20 wt.%). ACTIVITY - None given.    MECHANISM OF ACTION - None given.    ADMINISTRATION - The composition is administered orally. No dosage details given.    EXAMPLE - Carbamazepine (1 g) and nicotinamide (1 g) were mixed in the high pressure vessel in presence of 155 g of CO2 (40 degrees C, 100 bar) for 1.5 hours. Raman analysis showed that photon count maxima at Raman shifts typical for crystalline carbamazepine had completely vanished, count maxima for crystalline nicotinamide had decreased dramatically and new photon count maxima not representing carbamazepine or nicotinamide appeared, indicating complete conversion of the carbamazepine.