While continuing to occupy a smaller market share of drug delivery than oral solid dosage, parenteral formulations are today a major focal point – not least because of rapidly growing interest in biopharmaceuticals. Meanwhile, parenteral-grade excipients continue to be in short supply, are expensive to produce and require stringent test data. Sarah Williams speaks to Sandeep Nema, executive director portfolio and project management, global biologics, at Pfizer, about the challenges of formulating novel excipients, how the industry has progressed in recent years and where future developments might lead.