Betaxolol
Betaxolol. Cardioselective β1-adrenergic blocker. Oral form for hypertension; ophthalmic form (Betoptic) for glaucoma — preferred over timolol in… Oral half-life 18 h.
Cardioselective β1-adrenergic blocker. Oral form for hypertension; ophthalmic form (Betoptic) for glaucoma — preferred over timolol in patients with respiratory disease due to β1 selectivity reducing bronchospasm risk.
PK: FOUR VALUES REPLACED, ALL VERBATIM, AND THE REPLACEMENTS ARE MUTUALLY COHERENT. F 0.85 was a CROSS-ARM AVERAGE - the source reports "F: 0.88 +/- 0.08, 0.82 +/- 0.06, 0.84 +/- 0.07" for 10, 20 and 40 mg, whose mean is 0.847 - and becomes the 10 mg arm, matching this record typical dose; an independent study confirms the magnitude at "89 +/- 5%". ka 0.6 is probably that sentence STANDARD DEVIATION, since the only 0.6 in this literature is in "apparent absorption rate constant ... 1.0 +/- 0.6 versus 1.2 +/- 0.6 h-1", and it is independently wrong: 0.6 predicts a peak at 4.89 h, OUTSIDE the observed "3-4 h", while 1.0 predicts 3.36 h inside it. V 360 becomes the verbatim "342 +/- 62 versus 340 +/- 65 L", which is INTRAVENOUS so the F pairing stays correct. t-half 18 was neither endpoint nor midpoint of a printed "13-20 h" and becomes a verbatim 17.5 h. THE CHECK THAT MATTERS: the new set implies CL/F 15.4 L/h against a measured intravenous 15.6 and 16.4, and predicts Cmax 22.6 ug/L against an observed "21.6 +/- 3.7". IN FAIRNESS TO THE OLD RECORD, its exposure was never badly wrong, only about 7% off; what was wrong was that nothing but F traced to the cited paper, and a Tmax misplaced by 1.5 h. A rabbit anterior-chamber "volume of distribution" of 1421 microlitres was rejected. MATRIX CAVEAT: both studies assayed WHOLE BLOOD, harmless today but decisive before any ec50 is added. PK: THE STORED ABSORPTION RATE WAS THE SOLVER DEFAULT WEARING A CITATION. A ka of 1.0/h is exactly what resolvePk substitutes when the field is ABSENT, and no source on this record states one. Removing it is NUMERICALLY A NO-OP — the resolver supplies the identical number — so no curve moves; what changes is that the record stops asserting an absorption rate it never measured. This is the same shape already found on a volume of 35 L, which is likewise the default at the seventy-kilogram reference. THE WIDER DEBT IS LEFT ALONE ON PURPOSE: twelve values account for 152 of the 276 authored absorption rates, but the other eleven are NOT the default, so deleting those would move their curves rather than leave them, which is the error this audit spent a batch documenting.
Pharmacokinetics
- Oral — t½ 17.5 h · F 88% · Vd 342 L
Sources: PMID:2906367, PMID:1865331, PMID:6104498, PMID:6108127