Dapoxetine
Dapoxetine. SSRI purpose-engineered for short half-life (~90 min initial; ~19 h terminal but minor). Designed to get out fast enough for on-demand… Oral half-life 3 h.
SSRI purpose-engineered for short half-life (~90 min initial; ~19 h terminal but minor). Designed to get out fast enough for on-demand use without the chronic-SSRI side effect + withdrawal burden. Not approved in US (NDA withdrawn 2004).
PK: A 6.45x ERROR THAT DECOMPOSES EXACTLY INTO TWO NAMED CLASSES MULTIPLYING TOGETHER. Removing the double division by bioavailability accounts for 2.38x, and replacing a DISTRIBUTION half-life with an effective one accounts for 2.71x; their product is the whole error. The stored 1.4 h is verbatim but the same sentence names it: "Elimination was biphasic, with an initial half-life of approximately 1.4 hours and a terminal half-life of approximately 20 hours" — AND THIS RECORD OWN PROSE ALREADY SAID "~90 min initial; ~19 h terminal", so the author knew. The old set asserted 3163 mL/min, twice hepatic blood flow and roughly sixty percent of cardiac output, against a published 29.41 L/h. NEITHER PUBLISHED HALF-LIFE IS THE RIGHT MONO-EXPONENTIAL: the terminal one fails the exposure-to-peak floor by 4.8x while the distribution one passes, and the value satisfying the identity sits between them. All four adopted numbers are DERIVED rather than verbatim and are disclosed as such; the two-compartment slot is the physically right answer but no abstract states the transfer constant it needs. ka 1.77 is removed as a back-derivation of a rounded phrase — it solves to a peak at 0.9993 h against "approximately 1 hour after dosing" — where the measured value is 1.47 h.
Pharmacokinetics
- Oral — t½ 3 h · F 100% · ka 2.671 h⁻¹ · Vd 126 L
Sources: PMID:16490806, PMID:16920897, PMID:17322143