The DRI showed a considerable dose reduction for
herbal extracts and drugs used as a result of their synergism
(Table 3). When using synergistic drug combinations at
corresponding dose levels, the DRI indicated that the concentration
of doxorubicin necessary to inhibit the growth
of 50% of cancer cells (IC50) could be decreased 1.64-fold
(A549, P. emblica/doxorubicin) to 4.69-fold (HepG2, P. emblica/
doxorubicin), and the IC90 could be reduced 2.59-fold
(A549, P. emblica/cisplatin) to 2.60-fold (A549, P. emblica/
doxorubicin; Table 3). The dose reduction level was different
and specific to each combination and cell line.