Venlafaxine
Venlafaxine. Dose-dependent reuptake profile: SERT alone at ≤75 mg; adds NE at ~150 mg; DAT at ≥300 mg. Desvenlafaxine (Pristiq) is the major… Oral half-life 4 h.
Dose-dependent reuptake profile: SERT alone at ≤75 mg; adds NE at ~150 mg; DAT at ≥300 mg. Desvenlafaxine (Pristiq) is the major active metabolite. Short t½ and serotonergic → severe discontinuation syndrome (brain zaps).
PK: THE HALF-LIFE WAS REFUTED BY ITS OWN CITATION AND THE BIOAVAILABILITY WAS RIGHT UNDER THE WRONG ONE. PMID:1487561 states "Steady-state elimination half-life was 3 to 4 hours for venlafaxine and 10 hours for O-desmethylvenlafaxine"; the stored 5 is neither number nor their midpoint, and becomes the verbatim upper endpoint. F 0.45 moves to PMID:9549664, a four-way crossover with a genuine 10 mg INTRAVENOUS arm - "The absolute bioavailability of venlafaxine was between 40% and 45%" - where the previously cited abstract contains no bioavailability at all. ka 1.88 is the second member of the 1.5-hour generator, solving to Tmax 1.497 h against a measured 2-2.5 h; V 490 is reproducible from this record own numbers, CL/F 0.98 L/h/kg times 70 divided by the stored ke, giving 495. NO TRANSPLANT WITH DESVENLAFAXINE - both records were compared field by field from both sides and share no value. The real analyte issue is subtler and is recorded here: this models the MINOR circulating species, since "The area under the metabolite curve was two to three times greater than that for venlafaxine" and the metabolite has "almost equal activity", so a parent-only curve understates serotonergic exposure roughly threefold.
Pharmacokinetics
- Oral — t½ 4 h · F 45% · Vd 490 L
Sources: PMID:1487561, PMID:17497139, PMID:11750180, PMID:7856622, PMID:9549664, PMID:9537821