Possible Warfarin Interaction with Menthol Cough Drops

Kassebaum, Paul J; Shaw, Don L; Tomich, D

doi:10.1345/aph.1e537

Cited by 14 publications

(11 citation statements)

References 8 publications

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“…In addition, deteriorating asthma control has been reported with Echinacea use, likely due to an associated ragweed allergy since Echinacea and ragweed are members of the same plant family [80]. Lastly, case reports of urticaria and asthma, as well as decreases in international normalized ratio levels of patients on warfarin have been attributed to overdosing on the over-the-counter menthol throat lozenges [81–83]. …”

Section: Discussionmentioning

confidence: 99%

Health beliefs, treatment preferences and complementary and alternative medicine for asthma, smoking and lung cancer self-management in diverse Black communities

George

2012

Patient Education and Counseling

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Objectives The purpose of this literature review is to characterize unconventional health beliefs and complementary and alternative medicine (CAM) for asthma, smoking and lung cancer as those that are likely safe and those that likely increase risk in diverse Black communities. These findings should provide the impetus for enhanced patient-provider communication that elicits patients’ beliefs and self-management preferences so that they may be accommodated, or when necessary, reconciled through discussion and partnership. Methods Original research articles relevant to this topic were obtained by conducting a literature search of the PubMed Plus, PsychINFO and SCOPUS databases using combinations of the following search terms: asthma, lung cancer, emphysema, chronic obstructive pulmonary disease (COPD), smoking, beliefs, complementary medicine, alternative medicine, complementary and alternative medicine (CAM), explanatory models, African American, and Black. Results Using predetermined inclusion and exclusion criteria, 51 original research papers were retained. Taken together, they provide evidence that patients hold unconventional beliefs about the origins of asthma and lung cancer and the health risks of smoking, have negative opinions of standard medical and surgical treatments, and have favorable attitudes about using CAM. All but a small number of CAM and health behaviors were considered safe. Conclusions When patients’ unconventional beliefs and preferences are not identified and discussed, there is an increased risk that standard approaches to self-management of lung disease will be sub-optimal, that potentially dangerous CAM practices might be used and that timely medical interventions may be delayed. Practice implications Providers need effective communication skills as the medical dialogue forms the basis of patients’ understanding of disease and self-management options. The preferred endpoint of such discussions should be agreement around an integrated treatment plan that is effective, safe and acceptable to both.

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Section: Discussionmentioning

confidence: 99%

Health beliefs, treatment preferences and complementary and alternative medicine for asthma, smoking and lung cancer self-management in diverse Black communities

George

2012

Patient Education and Counseling

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“…At this dose, the clinical reports 5,6) showing that menthol attenuated an effect of warfarin were reproducible on mice. 7) When calculated based on the amount of menthol contained in foods (cough drop, menthol content: 1-10 mg/drop) and drugs (antiperistaltic drug, menthol content: 160 mg), the dose used in this study is equivalent to 5- to 100-fold the dose for humans.…”

Section: Discussionmentioning

confidence: 86%

“…Based on reports showing that the intake of menthol attenuates the anticoagulant effect of warfarin when concurrently administered, 5,6) we performed a pharmacokinetic study and demonstrated that menthol induces the expression of CYP3A and CYP2C, which are hepatic enzymes participating in the metabolism of warfarin, and thereby lowers the plasma concentration of warfarin, resulting in a reduced anticoagulant effect. 7) Menthol is contained in candies, cigarettes, and herbal teas, as well as pharmaceutical products, and its safety has been assured.…”

mentioning

confidence: 99%

Effects of Menthol on the Pharmacokinetics of Triazolam and Phenytoin

Hoshino

Ikarashi

Hirobe

et al. 2015

Biological & Pharmaceutical Bulletin

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We have previously shown that menthol attenuates the anticoagulant effect of warfarin by increasing the expression levels of CYP3A and CYP2C in the liver. This study evaluated the effects of menthol on the pharmacokinetics of the CYP3A substrate triazolam and the CYP2C substrate phenytoin. Menthol was orally administered to mice for 7 d. Twenty-four hours after the administration of menthol, triazolam was orally administered, and the plasma concentration was measured. In addition, the CYP3A metabolic activity for triazolam and the CYP3A expression level in the liver were determined. The effects of menthol on the pharmacokinetics of phenytoin were assessed in the same manner. In the menthol-treated group, the area under the blood concentration-time curve (AUC) of triazolam was lower and its clearance was higher compared with the control group. The CYP3A metabolic activity and CYP3A expression level in the liver were significantly increased in the menthol-treated group compared with the control group. Similarly, the AUC of phenytoin was lower and the hepatic CYP2C expression level was higher in the menthol-treated group. Thus, menthol lowered the plasma concentrations of triazolam and phenytoin when concurrently administered. These effects may be attributed to an increased metabolic activity for these drugs due to the increased expression of CYP3A and CYP2C in the liver.

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“…There are however two recently published reports claiming a probable interaction between warfarin and separate other brands of menthol-containing cough drops 3 4. In both cases, a drop in INR was observed soon after the patient began to consume the menthol drops regularly and the INR recovered back to the previous level on cessation of the drops, with the dose of warfarin subsequently being able to be lowered to the dose that was previously being taken to maintain a therapeutic INR.…”

Section: Discussionmentioning

confidence: 99%

“…It is not the only potentially active compound in most cough drops however and both ‘Fisherman’s Friend’ and the brand of cough drop cited as causing a potential reaction by Kassebaum et al 3 contain other potentially active substances, among them eucalyptus oil. Eucalyptus oil is present in many cough remedies, sweets, shampoos and herbal remedies in greatly varying concentrations and has in vitro at least the capacity to interact with P450 isoenzymes4 and therefore theoretically with the metabolism of warfarin in humans.…”

Section: Discussionmentioning

confidence: 99%

Clinically significant interaction between warfarin and popular cough lozenges 'Fisherman's Friend'

Boyle

Walters²

2011

Case Reports

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Possible Warfarin Interaction with Menthol Cough Drops

Abstract: This case documents a significant decrease in the INR following the use of menthol cough drops. Patients who are ill have several factors that can potentially affect their INR and should be monitored closely.

Cited by 14 publications

References 8 publications

Health beliefs, treatment preferences and complementary and alternative medicine for asthma, smoking and lung cancer self-management in diverse Black communities

Health beliefs, treatment preferences and complementary and alternative medicine for asthma, smoking and lung cancer self-management in diverse Black communities

Effects of Menthol on the Pharmacokinetics of Triazolam and Phenytoin

Clinically significant interaction between warfarin and popular cough lozenges 'Fisherman's Friend'

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