Evaluation of vitamin D medicines and dietary supplements and the physicochemical analysis of selected formulations.
J Nutr Health Aging. 2013 Feb;17(2):158-61. doi: 10.1007/s12603-012-0090-4.
Garg S1, Sabri D, Kanji J, Rakkar PS, Lee Y, Naidoo N, Svirskis D.
1School of Pharmacy, University of Auckland, Auckland, New Zealand. sanjay.garg at unisa.edu.au
Vitamin D is purported to offer wide ranging and numerous health benefits leading to increased interest from manufacturers of medicines and dietary supplements. Elderly patients frequently require vitamin D supplementation due to reduced sun exposure and dietary intake. There are ever increasing numbers of vitamin D formulations in the global market. However, due to a lack of regulatory restrictions for some of these products the quality of these dosage forms can be of some concern.
To study vitamin D formulations available in the global market and evaluate physic-chemical properties of selected formulations from the New Zealand market.
The first component of this study consisted of a search for different vitamin D formulations available in selected countries. The second component of the study involved assaying selected vitamin D formulations available in New Zealand. Vitamin D was extracted from capsule, tablet and emulsion formulations and quantified using a validated High Performance Liquid Chromatography (HPLC) method.
Of the 14 analysed formulations, only 60% were within 100±10 % of the label claim. The two registered, prescription formulations available exhibited vitamin D levels of 90±4% and 97±2% of the labeled amount, while non-registered, non-prescription dietary supplements had vitamin D levels ranging from 8±2% to 201±29% of the labeled amount.
Dietary supplements do not require strict regulation and showed a large variation in the percentage label claim of vitamin D. Prescription formulations which are more strictly regulated gave content values within standard acceptance ranges. Vitamin D has proven health benefits and also the potential to cause harm, therefore there is a need for tougher regulations of dietary supplements to ensure acceptable quality.
This study purchased pills which were claimed to have 500 – 1000 IU of vitamin D
Maximum claimed amount is 1000 IU in New Zealand
- Vitamin D sachets in India – fewer than a third had the stated amount – Nov 2013 vs 60% in NZ had within 10% of amount claimed on label
- Most vitamin D bought over-the-counter meet requirements – Feb 2013 US