The association between drugs frequently used by the elderly and vitamin D blood levels: a review of observational and experimental studies.
The risk of adverse drug reactions (ADRs) rises with increasing age. In the field of ADRs, drug-nutrient interactions (DNIs) are a relatively unexplored area. More knowledge will contribute to the simple prevention of this type of ADR. As the prevalence of vitamin D deficiency in the elderly is high, the primary objective of this review is to evaluate the literature on the relationship between drug use and vitamin D status, focusing on medicines commonly used by the elderly. PubMed was searched for human epidemiological and clinical studies published until early 2013, investigating the relationship between vitamin D blood levels and use of drugs from one of the following groups: proton pump inhibitors (PPIs), biguanides, vitamin K antagonists, platelet aggregation inhibitors, thiazide diuretics, loop diuretics, beta-blocking agents, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II antagonists, statins, benzodiazepines, and antidepressants. A total of 63 publications were identified. Thiazide diuretics, statins, and calcium channel blocking agents were the most frequently studied drug groups. Associations between thiazides and vitamin D were mixed (n = 22), statins had no or positive associations (n = 16) and calcium blockers were not associated or were negatively associated with vitamin D (n = 10). In conclusion, several knowledge gaps exist on the relationship between drug use and vitamin D blood levels. Available data are scarce (particularly for the aged), study characteristics are highly variable, and found associations may be confounded by, amongst other things, the underlying disease. Nonetheless, this review provides a basis for future research on ADRs that contribute to nutrient deficiencies.