Quinidine is used to treat and prevent certain forms of heart arrhythmia.
Summary of
Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem
contradictory. For clarification, read the full article for details about the summarized
interactions.
May Be Beneficial:Side effect
reduction/prevention—Taking these supplements may help reduce the likelihood and/or
severity of a potential side effect caused by the medication.
Beta-carotene
Magnesium
Potassium
May Be Beneficial:Supportive
interaction—Taking these supplements may support or otherwise help your medication
work better.
Food
Avoid:Reduced drug absorption/bioavailability—Avoid these supplements
when taking this medication since the supplement may decrease the absorption and/or activity
of the medication in the body.
High-salt diet
Avoid:Adverse interaction—Avoid these supplements when taking this
medication because taking them together may cause undesirable or dangerous results.
Food
Grapefruit juice
Low-salt diet
Pomegranate juice*
Sodium bicarbonate
Depletion or interference
None known
An asterisk (*) next to an item in the summary indicates that the
interaction is supported only by weak, fragmentary, and/or contradictory scientific
evidence.
Interactions with Dietary Supplements
Potassium and Magnesium
People taking potassium-depleting diuretics
may develop low potassium and magnesium blood levels. Prolonged diarrhea and vomiting might also result in low blood
potassium levels. People with low potassium or magnesium blood levels who take quinidine might
develop serious drug side effects.1 Therefore, people taking quinidine should have
their blood potassium and magnesium levels checked regularly and might need to supplement with
both minerals, especially when taking potassium-depleting diuretics.
Beta-carotene
Some people taking quinidine develop sensitivity to ultraviolet radiation from the sun. In a
preliminary study, three people with quinidine-induced skin inflammation were able to tolerate
intense sun exposure without recurrence of the rash after supplementing with 90–180 mg
of beta-carotene each day.2 Further research is needed to confirm that people
taking quinidine can prevent side effects by supplementing with beta-carotene.
Interaction with Foods and Other Compounds
Grapefruit
juice
Drinking grapefruit juice together with quinidine increases the amount of time that the drug
remains in the body,3 which might increase the likelihood of side effects and
toxicity. Therefore, based on currently available information, people taking quinidine should
avoid drinking grapefruit juice or eating grapefruit.
Pomegranate
juice
Pomegranate juice has been shown to inhibit the same enzyme that is inhibited by grapefruit juice.45 The degree
of inhibition is about the same for each of these juices. Therefore, it would be reasonable to
expect that pomegranate juice might interact with quinidine in the same way that grapefruit
juice does.
Salt
One controlled study showed that people consuming a high-salt diet had dramatically lower
quinidine blood levels compared with people on a low-salt diet.6 Problems might
occur when people switch from a high-salt diet to a low-salt diet and vice versa. Therefore, people taking
quinidine should notify their health practitioner before changing their salt intake.
Food
Taking quinidine with food greatly increases the speed and extent of absorption of the
drug.7 Serious problems might occur when people switch from taking quinidine with a
meal to taking it on an empty stomach and vice versa. Therefore, quinidine should be
consistently taken with a meal to enhance drug action and to avoid potential problems.
Sodium
bicarbonate
Sodium bicarbonate reduces the amount of quinidine eliminated from the body, which might
result in increased drug side effects and toxicity.8 Therefore, people taking
quinidine should avoid using antacids or toothpaste that contain sodium bicarbonate.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Roden DM, Iansmith DH. Effects of low potassium or magnesium
concentrations on isolated cardiac tissue. Am J Med 1987;82:18–23.
2. Fisher DA. Quinidine photosensitivity. Arch Dermatol
1984;120:298 [letter].
3. Damkier P, Hansen LL, Brosen K. Effect of diclofenac, disulfiram,
itraconazole, grapefruit juice and erythromycin on the pharmacokinetics of quinidine. Br J
Clin Pharmacol 1999;48:829–38.
4. Sorokin AV, Duncan B, Panetta R, Thompson PD. Rhabdomyolysis
associated with pomegranate juice consumption. Am J Cardiol 2006;98:705–6.
5. Summers KM. Potential drug-food interactions with pomegranate juice.
Ann Pharmacother 2006;40:1472–3.
6. Darbar D, Dell’Orto S, Morike K, et al. Dietary salt increases
first-pass elimination of oral quinidine. Clin Pharmacol Ther
1997;61:292–300.
7. Sifton DW, et. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 757–60.
8. Sifton DW, et. Physicians’ Desk Reference. Montvale,
NJ: Medical Economics Company, Inc., 2000, 757–60.
The information presented in Aisle7 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, practitioner, and/or pharmacist
for any health problem and before using any supplements or before making any changes in
prescribed medications. Information expires February 2010.
