Chlorzoxazone

Safetychecker Summary for Chlorzoxazone
(for details about the summarized interactions, read the full article)

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.	Brussels sprouts Broccoli Chinese cabbage Garlic Tea Watercress
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	Caffeine* Alcohol
Depletion or interference	None known
Side effect reduction/prevention	None known
Supportive interaction	None known

Interactions with Foods and Other Compounds

Food
Test tube studies show that watercress, garlic, tea, and cruciferous vegetables, such as Brussels sprouts, broccoli, and Chinese cabbage, block the breakdown of chlorzoxazone into inactive compounds.¹ ² Controlled human research is needed to determine whether these interactions are important in people taking chlorzoxazone.

Alcohol
Drinking alcoholic beverages while taking chlorzoxazone may enhance side effects of the drug, such as drowsiness, dizziness, and light-headedness.³ In addition, test tube studies show that alcohol might increase the elimination of chlorzoxazone from the body.⁴ Consequently, people who are taking chlorzoxazone should avoid drinking alcohol.

Smoking
Studies show that cigarette smoking increases the elimination of chlorzoxazone from the body.⁵ Problems could occur if people either start or stop smoking while taking chlorzoxazone: individuals who stop smoking may experience increased side effects, while those who start smoking may notice that the drug is less effective.

Caffeine
Controlled studies show that chlorzoxazone reduces the elimination of caffeine from the body,⁶ which could cause side effects of caffeine, such as restlessness and insomnia. If side effects occur, some individuals may need to avoid caffeinated beverages, such as coffee and tea, while taking chlorzoxazone.

References:

1. Walter-Sack I, Klotz U. Influence of diet and nutritional status on drug metabolism. Clin Pharmacokin 1996;31:47–64.

2. Marchand LL, Wilkinson GR, Wilkens LR. Genetic and dietary predictors of CYP2E1 activity: a phenotyping study in Hawaii Japanese using chlorzoxazone. Cancer Epidemiol Biomarkers Prev 1999;8:495–500.

3. Sifton DW, ed. Physicians Desk Reference. Montvale, NJ: Medical Economics Company, Inc., 2000, 2200.

4. Klotz U, Ammon E. Clinical and toxicological consequences of the inductive potential of ethanol. Eur J Clin Pharmacol 1998;54:7–12.

5. Zevin S, Benowitz NC. Drug interactions with tobacco smoking. An update. Clin Pharmacokinet 1999;36:425–38.

6. Berthou F, Goasduff T, Lucas D, et al. Interaction between two probes used for phenotyping cytochromes P4501A2 (caffeine) and P4502E1 (chlorzoxazone) in humans. Pharmacogenetics 1995;5:72–9.

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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, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2003.