Interactions with Dietary Supplements
Potassium
An uncommon yet potentially serious side effect of taking ACE inhibitors is increased blood
potassium levels.1 2 3 This problem is more likely to occur
in people with advanced kidney disease. Taking potassium supplements,4
potassium-containing salt substitutes (No Salt®, Morton Salt Substitute®, and
others),5 6 7 or large amounts of high-potassium foods (such
as bananas and other fruit) at the same time as taking ACE inhibitors could cause
life-threatening problems.8 Therefore, people should consult their healthcare
practitioner before supplementing additional potassium and should have their blood levels of
potassium checked periodically while taking ACE inhibitors.
Lithium
Lithium is a mineral that may be present in some supplements and is also used in large amounts
to treat mood disorders, such as bipolar disorder. Taking lithium at the same time as ACE
inhibitors may increase blood levels of the mineral.9 Controlled studies are needed
to determine whether taking moexipril together with the tiny amounts of lithium present in
some supplements might produce similar side effects. People taking moexipril should exercise
caution when supplementing with lithium until more information is available.
Iron
In a double-blind study of patients who had developed a cough attributed to an ACE inhibitor,
supplementation with iron (in the form of 256 mg of ferrous sulfate per day) for four weeks
reduced the severity of the cough by a statistically significant 45%, compared with a
nonsignificant 8% improvement in the placebo group.10
Interactions with Foods and Other Compounds
Food
Taking moexipril with food dramatically reduces the absorption of the drug, especially when
taken with a high-fat meal.11 Therefore, moexipril should be taken an hour before
or two hours after a meal.
Low-salt diet
Taking moexipril while on a low-salt diet might cause excessively low blood
pressure.12 Therefore, people taking moexipril should notify their healthcare
practitioner before starting a low-salt diet.
References:
1. Good CB, McDermott L, McCloskey B. Diet and serum potassium in
patients on ACE inhibitors. JAMA 1995;274:538.
2. Rush JE, Merrill DD. The Safety and tolerability of lisinopril in
clinical trials. J Cardiovasc Pharmacol 1987;9(Suppl 3):S99–107.
3. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 1965–8.
4. Burnakis TG, Mioduch HJ. Combined therapy with captopril and potassium
supplementation. A potential for hyperkalemia. Arch Intern Med
1984;144:2371–2.
5. Burnakis TG. Captopril and increased serum potassium levels.
JAMA 1984;252:1682–3 [letter].
6. Ray K, Dorman S, Watson R. Severe hyperkalemia due to the concomitant
use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening
interaction. J Hum Hypertens 1999;13:717–20.
7. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 1965–8.
8. Stoltz ML. Severe hyperkalemia during very-low-calorie diets and
angiotensin converting enzyme use. JAMA 1990;264:2737–8 [letter].
9. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 2871–3.
10. Lee SC, Park SW, Kim DK, et al. Iron supplementation inhibits cough
associated with ACE inhibitors. Hypertension 2001;38:166–70.
11. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 2871–3.
12. Sifton DW, ed. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 2871–3.
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The information presented in Healthnotes is for informational
purposes only. It is based on scientific studies (human, animal, or in vitro),
clinical experience, or traditional usage as cited in each article. The results reported may
not necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over-the-counter medication is also available. Consult your doctor,
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before making any changes in prescribed medications. Information expires December 2003.