excipient William R. Hogan a role of a scattered molecular aggregate in aiding the manufacture, prolonging the shelf life, or ensuring proper administration of a drug product excipient role not all excipients aid in delivery of the drug, although it is their most common role. examples include preservatives and sorbents. some excipients are used in manufacture of a drug product and do not end up being part of the drug product at the end, for example, water in the manufacture of lyophilized products and inert gasses in the headspace of containers (http://www.ipapharma.org/epharmatimes/Mar2013/#65). the net result is that the aggregate bearing the excipient role need not be part of the drug product. role of scattered molecular aggregate