Evaluation of vitamin D medicines and dietary supplements and the physicochemical analysis of selected formulations.
BACKGROUND
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.


OBJECTIVE
To study vitamin D formulations available in the global market and evaluate physic-chemical properties of selected formulations from the New Zealand market.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
School of Pharmacy, University of Auckland, Auckland, New Zealand. sanjay.garg@unisa.edu.au
S
S
Garg
D
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Sabri
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J
Kanji
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PS
Rakkar
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Lee
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Naidoo
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D
Svirskis
D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D019587:Dietary Supplements / Q000032:analysis* / Q000592:standards; D004304:Dosage Forms; D004348:Drug Labeling / Q000592:standards*; D006801:Humans; D009520:New Zealand; D004364:Pharmaceutical Preparations / Q000032:analysis* / Q000592:standards; D014807:Vitamin D / Q000008:administration & dosage* / Q000032:analysis
D004304:Dosage Forms; D004364:Pharmaceutical Preparations; D014807:Vitamin D