Anticancer agents, problems, selectivity: terrible, ty to kill all our own cells, resistance by tumor cells. Inadequate host defense: disease and treatment decrease immune response: cell cycle, s phase specific. Arab: others are phase non-specific, mechanism, have to act on rapidly growing tumor. If the doubling time takes too long (80-90 days), like lung and colon cancer, drugs are not effective (low growth fraction is bad: toxic and growth fraction. If the tissue has high gf, when the anticancer drugs kill the cancer cells, the healthy tissues will be affected too. Reproductive, cns, kidney too: alkylating agents, cyclophosphamide. Mechanism: cross-links dna (no replication), inhibit dna & rna synthesis. Cell specificity: nonspecific cell cycle, proliferation dependent more effective in growing tumor resistance: decrease uptake, excision-repair dna rapid iv infusion, app 1 min circulation time is 6hrs, drugs affect p450 can affect circulation time. Mechanism: competitive inhibitor of fh2 reductase, no dna synthesis. Use: cns complication from leukemia, osteogenic sarcoma.