Articles

Drug Interactions with Vitamins and Minerals

By Pete Hueseman, R.Ph.

Supplement use is typically a safe and effective method of maintaining a healthy body; however, supplements have the potential to interact with prescribed medications. This could be cause for concern since 52% of adults take dietary supplements1. Vitamins and minerals serve crucial functions in almost all bodily processes and must be obtained from foods or supplements, as our bodies are unable to make them. The risks increase as patients get older, because they are possibly on multiple medications, along with the supplements. As the patients age the liver and kidney functions also decrease, and these two organs are the main organs the drugs, minerals, and vitamins are metabolized through.
Patients need to consider discontinuing use of supplements while on an antibiotic. If an antibiotic is added for a short term use and one or more of the supplements might make it less effective while being used, consider discontinuing the supplements during that short time period, or changing the supplement when possible. For example, if an antibiotic of Tetracycline or Fluroquinolones is given to a patient treating an ulcer or GERD with an antacid, then an alternative could be used while on the antibiotic such as an H2-blocker or proton pump inhibitor, since the magnesium and calcium in the antacid would make the antibiotic less effective.

Some of the vitamins and minerals that cause some of the most common interactions follow:

Vitamin-A: a fat soluble vitamin found in some foods, liver, yellow-orange fruits and vegetables such as carrots, margarine, milk, spinach, and found in many multivitamins. Vitamin A helps with vision, bone growth, cell differentiation, and the immune system. The biggest interaction is with the retinoids such as isotretinoin (Accutane) and acitretin (Soriatane) which are for acne and psoriasis. Vitamin A toxicity can cause nausea, vomiting, poor muscle coordination, blurred vision and dizziness.

Vitamin B-6 (pyridoxine): a water soluble vitamin that treats some types of anemia and other B-6 deficiencies. It is found in vitamin supplements or alone and in the following foods: meats, some fruits and vegetables, and whole grains. It will decrease the effects of Phenytoin (Dilantin) and Levodopa alone. The decreasing effect is usually with 200mg per day or more for the Phenytoin, and 10 to 25 mg make the difference with levodopa, therefore add carbidopa to the therapy2.

Vitamin-E: a fat soluble vitamin that can help atherosclerosis, Alzheimer’s disease, some cancers, and cardiovascular disease. In the patient taking Warfarin the dose needs to be kept less than 800 IU per day to decrease the risk of bleeding. The amount in a multivitamin would be fine for this patient and not to add extra to the daily regimen. Vitamin E is also an antioxidant and if a patient is on chemotherapy it could interfere with the oxidative mechanism of the chemotherapy; so this patient should discuss with their oncologist how much to take if any.

Vitamin-K: can cause clotting and should not be used with warfarin or the warfarin activity is greatly decreased. It is found in the leafy vegetables like spinach and broccoli; and once on warfarin a patient should keep the diet consisting of those vegetables and multivitamins with a low dose in it consistent so the warfarin can be adjusted for the patient accurately.

Niacin: a water soluble B-Complex vitamin, used for pellagra and some hyperlipidemia. If used with statins it can increase risk of myopathies (pain). This usually only occurs if the Niacin is greater than 1,000mg/day.

Folic Acid: another B-Complex vitamin and used to treat folic acid deficiencies. It is used quite often with methotrexate as a prophylaxis to reduce toxicities in patients with psoriasis and rheumatoid arthritis.

Calcium: a mineral and used primarily to prevent and treat osteoporosis. It can be a supplement or found in antacids. Already mentioned was the interaction with antibiotics. If nothing else can be used in place of the calcium, then take the antibiotics and the calcium at 2 to 3 hours minimum in between the two with 4 to 6 hours being the best time frame in between. Corticosteroids decrease the absorption of calcium and this can lead to osteoporosis.

Aluminum and Magnesium: are minerals rarely found alone, but in combination vitamin and mineral supplements or antacids. The same rules apply as with calcium, previously mentioned. Aluminum and magnesium can also interfere with absorption of biphosphonates and Levothyroxine prescriptions, and should be taken 2 or more hours away from the prescription medications.

Iron: needed when the body CANNOT produce enough red blood cells. Symptoms of lack of iron could be tiredness, shortness of breath, decreased physical performance, increased infections. Do NOT use iron products within 2 hours of the following prescriptions: tetracyclines, Fluroquinolones, digoxin, and Levothyroxine. Also, dose them away from calcium supplements. Iron can interfere with levodopa absorption and decrease levodopa peak levels by 55%. The absorption of iron can also be decreased by patients also taking proton pump inhibitors.

Potassium: usually taken as prescription only and patients should not add extra unless told to do so by their physician. One must try to avoid hyperkalemia and discuss potassium intake with their physician if on these medications: ACE inhibitors, ARB’s, digoxin, Indomethacin; prescription potassium, potassium sparing diuretics. The small amount of potassium in vitamins will usually not be a problem, but salt substitutes can be a major problem. For ¼ teaspoonful of NoSalt= 650mg of potassium, and note that a potassium 20mEQ tablet on prescription contains 780mg of potassium; therefore it is very easy to overdose on potassium.

In conclusion, it is recommended that you discuss your supplements with your pharmacist and fill all your prescriptions at the same pharmacy. This way you can avoid the interactions which can attribute to poor outcomes or adverse events.

As an extra bit of advice for patients on hormone therapy: when on an antibiotic for infection it can make the hormones seem less effective for as long as ten days after stopping the antibiotics.

Sources:
1.)Radimer K, Bindewald B, Hughes J, et al. Dietary supplement use by US adults: data from the National Health and nutrition Examination Survey, 1999-2000. Am.J. Epidemiol. 2004;160:339-349.

2.)Sulli, M.M.; Ezzo, D.C.. Drug Interaction with Vitamins and Minerals. U.S. Pharmacist. 2007; 42-55.