I have not taken Tapentadol but I found that it's got a half-life of about 4 hours, so I'd say you should be good to take 6-APB 24 hours after your last Tapentadol dose, at least there won't be any risk of serotonin syndrome.
Tapentadol Metabolism and Elimination
In humans, the metabolism of tapentadol is extensive. About 97% of the parent compound is metabolized. Tapentadol is mainly metabolized via Phase 2 pathways, and only a small amount is metabolized by Phase 1 oxidative pathways. The major pathway of tapentadol metabolism is conjugation with glucuronic acid to produce glucuronides. After oral administration approximately 70% (55% O-glucuronide and 15% sulfate of tapentadol) of the dose is excreted in urine in the conjugated form. A total of 3% of drug was excreted in urine as unchanged drug. Tapentadol is additionally metabolized to N-desmethyl tapentadol 13% by CYP2C9 and CYP2C19 and to hydroxy tapentadol 2% by CYP2D6, which are further metabolized by conjugation. Therefore, drug metabolism mediated by cytochrome P450 system is of less importance than phase 2 conjugation.
None of the metabolites contributes to the analgesic activity.
Tapentadol and its metabolites are excreted almost exclusively (99% via the kidneys. The terminal half-life is on average 4 hours after oral administration. The total clearance is 1530 +/- 177 ml/min.
