Figure 5. Enhancement of liposomal doxorubicin accumulation and toxicity after pretreatment of NCI-ADR-RES spheroids. NCI-ADR-RES spheroids were preincubated with cytotoxic doses of priming drugs before addition of Lipo-Dox (LDOX, 100 µM): sclareol (SCL + LDOX), dexamethasone (DXM + LDOX), cisplatin (CIS + LDOX), methotrexate (MTX + LDOX), paclitaxel (PTX + LDOX), mitoxantrone (MXO + LDOX) or LDOX alone (LDOX). The accumulation of doxorubicin (black bars) was quantitated (Fig. 2). LDH release (white bars) was measured (Fig. 1). Data represent the mean ± SD, n = 3. Student’s t-test; **p < 0.01 compared with unprimed group.