Medicinal chemistry and pharmaceutical chemistry are disciplines of pharmacy on the intersection of chemistry, specially synthetic organic chemistry, and pharmacology and numerous other biological specialties, where they may be concerned with design, chemical synthesis and improvement for market of pharmaceutical agents, or bio-active molecules. Compounds used as drugs are most customarily organic compounds, which can be regularly divided into the broad classes of small natural molecules and "biologics", the latter of which can be most customarily medicinal preparations of proteins. Inorganic and organometallic compounds are also useful as drugs.