In addition space is not limited to binary combinations (acid-base pairs) since tertiary and quaternary co-crystals are realistic one (Indian J Pharm Sci.)

In addition, co-crystals of the muscle relaxant metaxalone have been reported to improve preclinical in vivo bioavailability. (Dove Press)

As part of an effort to clarify and help advance the development of pharmaceutical co-crystals, the US Food and Drug Administration (FDA) on Tuesday released revised draft guidance providing information on the appropriate classification of co-crystal solid-state forms, the data that should be submitted to support the classification and the regulatory implications of such a classification. (Regulatory Focus™)