Dextromethorphan-Quinidine

Drug Information

Summary of Interactions with Vitamins, Herbs, & Foods

Types of interactions:BeneficialAdverseCheck

Replenish Depleted Nutrients

  • none

Reduce Side Effects

  • 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. Further research is needed to confirm that people taking quinidine can prevent side effects by supplementing with beta-carotene.

  • Magnesium

    Two individuals taking sotalol developed a side effect of the drug (a heart arrhythmia known as torsades de pointes) which was effectively treated with intravenous magnesium. Additional research is needed to determine whether people taking sotalol might be able to prevent this side effect by taking supplemental magnesium.

Support Medicine

  • none

Reduces Effectiveness

  • none

Potential Negative Interaction

  • Drinking grapefruit juice together with quinidine increases the amount of time that the drug remains in the body, 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 has been shown to inhibit the same enzyme that is inhibited by grapefruit juice. 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.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Explanation Required

  • 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. 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.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
  • 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. 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.

    The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

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