Whilst innovation in inhaler devices and device components has been a regular occurrence over recent years, the same degree of novelty has not taken place in formulation science for drug delivery systems for inhalation. Perhaps a major constraint in innovation for formulation design is the limited number of excipients currently approved by the regulatory authorities for inhalation medicines, and the somewhat demanding requirements associated with the approval of additional excipients by regulators to this list even for those materials already approved for alternative routes of delivery. There are however a small number of exceptions to this scenario. The regulatory enforced changes associated with the new approved propellants for MDIs have been managed with the introduction of reformulated products, and through the approval of MDIs containing new NCEs onto the market. Also, with the growing desire to formulate inhaled medicines containing biotech based therapeutic agents, the drive to identify other suitable excipients to enable the preparation of stable, quality and efficacious inhalable medicines has increased. And there has been success in this particular field, although great care must be taken when generating micron sized particles of such sensitive materials