SN-38 (NK012) is an active metabolite of CPT-11, inhibitsDNA topoisomerase I, DNA synthesis and causes frequent DNA single-strand breaks. SN-38 inducesautophagy. In vitro
SN-38, a biological active metabolite of irinotecan hydrochloride (CPT-11). SN-38 causes the strongest inhibition of DNA topoisomerase I, followed by CPT and then CPT-11. CPT-11 dose dependently shifts the position of relaxed DNA in the direction of nicked DNA, but SN-38 and CPT shows no effect on the position of relaxed DNA. SN-38 dose-dependently and time-dependently inhibit DNA synthesis. Respective IC50 values of SN-38, in DNA synthesis is 0.077 μM. The inhibitory effect of SN-38 on RNA synthesis is less than that on DNA synthesis and it does not inhibit protein synthesis. SN-38 caused frequent DNA single-strand breaks in P388 cells.
In vivo
After oral dosing, peak SN-38 concentrations occurrs within 1 h, and the The percent unbound SN-38 lactone in murine plasma at 1000 ng/mL is 3.4 +/- 0.67%, whereas at 100 ng/mL the percent unbound is 1.18 +/- 0.14%. SN-38 lactone AUCs in micebearing human neuroblastoma xenografts are greater than in nontumor-bearing animals. Cell Data
