Understanding the interaction between food and treatment

Garlic (Allium sativum) is widely used as a folk remedy for hypertension, atherosclerosis, and cancer. Garlic may also change docetaxel clearance in breast cancer patients, though this finding is preliminary.⁶ Docetaxel is metabolized by CYP enzymes modulated by chemicals from garlic, particularly allicin.¹² Laboratory and animal studies suggest both inhibition and activation of these enzymes. Garlic has been shown to alter the interaction between two antiretroviral drugs affected by CYP enzymes.¹² However, the clinical implications of laboratory studies on the interaction between dietary garlic and chemotherapy drugs are far from clear.

Docetaxel is metabolized by the enzyme CYP3A4, and drug clearance has been found to be progressively slower through time in the presence of garlic allicin, although the trend has not reached statistical significance in available studies.¹² Clinical data suggest garlic may inhibit docetaxel metabolism in some patients, but clinical results have been inconsistent.¹² Until more is known, patients should be discouraged from using it during cancer chemotherapy.

Ginkgo biloba is a folk remedy used by some cancer patients for memory loss and dementia. Patients undergoing radiation and chemotherapy frequently experience neuropathies and impaired cognitive performance. Drug interactions between ginkgo and blood thinners have been identified. However, the metabolic pathways and enzyme interactions of ginkgo-derived chemicals in the gut are not known. Laboratory and animal studies suggest gingko chemicals can both activate and inhibit CYP enzymes involved in drug metabolism, leading some authors to suggest that clinically relevant drug interactions are possible or likely.¹² Laboratory animal studies suggest gingko alters the metabolism for heart drugs, asthma and emphysema drugs, and psychiatric drugs, such as alprazolam.¹² Human studies have been inconsistent, however, and the effects of ginkgo on chemotherapy drug metabolism is unknown. Caution dictates that until more is known, it should not be used by cancer patients undergoing chemotherapy.

Fish and fish oil consumption are associated with lower rates of several cancers. Many fish are rich in anti-inflammatory omega-3 fatty acids and docosahexaenoic acid, both of which have been tied epidemiologically to a reduced risk of numerous cancers. The fatty acids in fish oil may have an influence on the effectiveness of chemotherapy drugs; however, no human clinical trials have confirmed any suggestive findings from animal and in vitro laboratory studies.¹³ ONA

Bryant Furlow is a medical writer in Albuquerque, New Mexico.

DRUGS MENTIONED

Alprazolam (Niravam, Xanax, generics) Imatinib (Gleevec)

Bortezomib (Velcade) Irinotecan (Camptosar, generics)

Docetaxel (Taxotere) Lapatinib (Tykerb)

Etoposide (VePesid, generics) Nilotinib (Tasigna)

REFERENCES

1. Marchetti S, Mazzanti R, Beinjnen JH, Schellens JH. Concise review: Clinical relevance of drug drug and herb drug interactions mediated by the ABC transporter ABCB1 (MDR1, P-glycoprotein). Oncologist. 2007;12(8):927-941.

2. Koch KM, Reddy NJ, Cohen RB, et al. Effects of food on the relative bioavailability of lapatinib in cancer patients. J Clin Oncol. 2009;27(8):1191-1196.

3. Tanaka C, Yin OP, Sethuraman V, et al. Clinical pharmacokinetics of the BCR-ABL tyrosine kinase inhibitor nilotinib. Clin Pharmacol Ther. 2010;87(2):197-203.

4. Singh BN. Effects of food on clinical pharmacokinetics. Clin Pharmacokinet. 1999;37(3):213-255.

5. Bar-Sela G, Epelbaum R, Schaffer M. Curcumin as an anti-cancer agent: review of the gap between basic and clinical applications. Curr Med Chem. 2010;17(3):190-197.

6. Yang AK, He SM, Liu L, et al. Herbal interactions with anticancer drugs: mechanistic and clinical considerations. Curr Med Chem. 2010;17(16):1635-1678.

7. Corner J, Yardley J, Maher EJ, et al. Patterns of complementary and alternative medicine use among patients undergoing cancer treatment. Eur J Cancer Care (Engl). 2009;18(3):271-279.

8. Lawenda BD, Kelly KM, Ladas EJ, et al. Should supplemental antioxidant administration be avoided during chemotherapy and radiation therapy? J Natl Cancer Inst. 2008;100(11):773-783.

9. Perrone G, Hideshima T, Ikeda H, et al. Ascorbic acid inhibits antitumor activity of bortezomib in vivo. Leukemia. 2009;23(9):1679-1686.

10. Clauson KA, Santamarina ML, Rutledge JC. Clinically relevant safety issues associated with St. John’s wort product labels. BMC Complement Altern Med. 2008;8:42.

11. Meyerhardt JA, Niedzwiecki D, Hollis D, et al. Association of dietary patterns with cancer recurrence and survival in patients with stage III colon cancer. JAMA. 2007;298(7):754-764.

12. Meirjerman I, Beijnen JH, Schellens JH. Herb-drug interactions in oncology: focus on mechanisms of induction. Oncologist. 2006;11(7):742-752.

13. Shaikh IA, Brown I, Wahle KW, Heys SD. Enhancing cytotoxic therapies for breast and prostate cancers with polyunsaturated fatty acids. Nutr Cancer. 2010;62(3):284-296.

From the August 01, 2010 Issue of Oncology Nurse Advisor