Drug-herb and drug-nutrient interactions can
adversely influence the clinical response to
treatment. "erefore, the effect of herbal and
nutrient compounds on hepatic metabolic enzymes
that influence drug pharmacokinetics is an area of
interest in modern medicine. Singh et al reported
that an 80-percent hydroalcohol extract (50 and
100 mg/kg/day for 14 days) of A. paniculata to mice
significantly increased the levels of acid-soluble
sulfhydryl content, cytochrome P450 (CYP450),
cytochrome P450 reductase, cytochrome b5
reductase, glutathione S-transferase, and superoxide
dismutase at both doses; while significant
increases in the levels of catalase, glutathione
peroxidase, and glutathione reductase were
observed only at higher doses.34 Both aqueous and
alcoholic extracts of A. paniculata are reported to
significantly increase the activities of CYP1A1 and
CYP2B without affecting the total hepatic CYP450
contents in ICR male mice.35 Andrographolide
significantly induced CYP1A1 and CYP1A2 mRNA
expression in cultures of mouse hepatocytes and
acted synergistically with CYP1A inducers.36 A.
paniculata extract has recently been reported to
noncompetitively inhibit CYP1A2 and CYP2C in rat
and human liver microsomes and competitively
inhibit CYP3A4 in human microsomes; whereas,
andrographolide was found to be a weak inhibitor
of rat CYP2E1 only.37 Similar effects of the extract
and andrographolide on CYP2C and CYP3A in rat
and human hepatocyte cultures have been
observed.38 Existing evidence is not sufficient to
draw any conclusions on drug-herb interactions.
More extensive studies on hepatic metabolizing
enzymes should be conducted in healthy humans
and in humans taking medications that are
susceptible to pharmacokinetic alterations by these
inducible hepatic enzymes.