Quality and use of unlicensed vitamin D preparations in primary care in England: Retrospective review of national prescription data and laboratory analysis

Aim To evaluate the type (licensed vs unlicensed) and cost of preparations used to fulfil vitamin D prescriptions in England over time, and to compare measured vitamin D content of selected vitamin D preparations against labelled claim. Methods Retrospective analysis of vitamin D prescription data in primary care in England (2008‐2018). Laboratory analysis of 13 selected vitamin D preparations. Results Alongside a rise in the number of oral licensed colecalciferol preparations from 0 to 27 between 2012 and 2018, the proportion of vitamin D prescriptions in which licensed vitamin D preparations were supplied increased from 11.8 to 54.2%. However, the use of unlicensed food supplements (dose strength 400‐50 000 IU) remained high, accounting for 39.7% of vitamin D prescriptions in 2018. The two licensed preparations showed mean (±SD) vitamin D content of 90.9 ± 0.7% and 90.5 ± 3.9% of the labelled claimed amount, meeting the British Pharmacopeia specification for licensed medicines (90‐125% of labelled claim). The 11 food supplements showed vitamin D content ranging from 41.2 ± 10.6% to 165.3 ± 17.8% of the labelled claim, with eight of the preparations failing to comply with the food supplement specification (80‐150% of labelled claim). Conclusions Despite the increasing availability of quality assured licensed preparations, food supplements continued to be used interchangeably with licensed preparations to fulfil vitamin D prescriptions. Food supplements, manufactured under less stringent quality standards, showed wide variations between measured and declared vitamin D content, which could lead to the risk of under‐ and over‐dosing.