Table 2.

Inducers and Inhibitors of CYP1A2 Activity in Humans.

Substance/Activity	Directional Change	Note	Reference
Fasting	↑	36 h fasted.	[78]
Fasting	↑	36 h fasted.	[79]
Grapefruit Juice Grapefruit Juice Ciprofloxacin Growth Hormone	↔ ↓ ↓ ↑	200 mL single and repeat dose (1.2 L). 300 mL repeat dose (1.2 L). 750 mg x 3 doses. Effect is shared with many but not all quinolones. Healthy elderly men. Twelve week use.	[80] [81] [82,83,84] [85]
Growth Hormone	↔	Growth hormone deficient children. Four week use. Similar results in six month study.	[86,87]
Herbal Dietary Supplement Heavy/Vigorous Exercise Heavy/Vigorous Exercise Rifampin	↑ ↑ ↑ ↑	2-4 capsules x 3 days. Extracts containing kola nut, grape, green tea and Ginkgo biloba. 8-11 hours daily x 30 days. Single maximal exercise cycle test in young hockey players. 600 mg x 7 days.	[88] [89,90] [91] [92]