Aim The UK incidence of vitamin D prescribing in children has increased by 26-fold in recent years.1 Public Health England recommends that children over 1 year take a daily vitamin D supplement.2 But the availability of over 200 different vitamin D products can be confusing for parents and clinicians. Our study aimed to assess the usage of licensed and unlicensed vitamin D only (VDO) preparations across primary care in England, and to compare measured and labelled vitamin D content of VDO preparations marketed in England.
Method Analysis of the vitamin D content of randomly selected VDO preparations using reversed-phase high performance liquid chromatography. Retrospective trend analysis of prescription reimbursement data for VDO prescriptions from 2008 to 2018.
Results Licensed and unlicensed VDO preparations were available in a wide range of dose strengths from 400 to 50,000 IU. The number of licensed VDO preparations increased from 4 to 32 between 2008 and 2018, along with an increase in the proportion of VDO prescriptions fulfilled by licensed preparations. However, prescriptions of unlicensed preparations remained high and accounted for 42% of the prescription items in 2018. The 11 unlicensed preparations analysed had vitamin D concentrations ranging from 41.2 ± 10.6% to 165.3 ± 17.8% of the declared content, with only one meeting the acceptable criteria of 90-125%. The 2 licensed preparations met the required standards. There was no association between the preparation dose strength and the magnitude of percentage difference between measured and labelled contents (r=0.41, p =0.17). Unlicensed liquid preparations in dropper bottles showed the greatest inter-sample variability suggesting there may be a lack of uniformity in drop volume delivered which could lead to dose variability.
Conclusion Despite the increasing availability of licensed preparations with assured quality, use of unlicensed preparations to fulfil VDO prescriptions has continued in primary care in England. Unlicensed VDO preparations marketed showed wide variations between measured and declared vitamin D contents. Younger children who are more vulnerable to harm are thus exposed to unnecessary risks of under- and over-supplementation.
Wan M, Horsfall L, Basatemur E, et al. Vitamin D prescribing in children in UK primary care practices: a population-based cohort study. BMJ 2019;9:e031870.
Scientific Advisory Committee on Nutrition. SACN vitamin D and health report 2016. Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/537616/SACN_Vitamin_D_and_Health_report.pdf
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