Calcium Impairs Absorption of Certain Antibiotics

Calcium-rich foods, such as dairy products and tofu, even milk added to tea or coffee, are sufficient to significantly impede the absorption of several antibiotics, including tetracycline, minocycline, doxy- cycline, levofloxacin, and ciprofloxacin [1]. To improve their absorption, these medications should be taken 1 h before or 2 h after calcium, magnesium, and iron supplements or dairy products.

Ginger Enhances Anticoagulant Effects

Ginger is a widely used condiment, food, and herbal medicine. It is used as a digestive aid, to treat inflammation, for morning sickness, but also has antiplatelet and antimicrobial effects. Ginger therefore has the potential to interact with anticoagulants. In the scientific literature, there are a few reports of an increase in the International Normalized Ratio (INR) in patients taking ginger root, ginger tea, and other herbal medicines containing ginger, in conjunction with warfarin [2]. The INR is an alternate measure of the common coagulation test known as prothrombin time (PT) and was introduced by the World Health Organization. A normal INR is approximately 0.9—1.1 and is elevated to between 2 and 3.5 when patients are on warfarin therapy, so an elevation in the case of ginger supplementation indicates that ginger has anticoagulant effects. One longitudinal study showed that concurrent administration of warfarin with a ginger product resulted in a statistically significant increase in bleeding episodes [2]. In addition, it has been shown that ginger and/or its chemical components inhibit cytochrome P450 (CYP450) isoenzymes. This action may be due to mutual competitive inhibition, mechanism-based inhibition, or nonselective inhibition of CPYs. These effects of ginger on the activity of CPYs may result in alterations in the pharmacokinetics and pharmacodynamics of co-administered drugs.

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