Labetalol
Labetalol. Combined α1 + non-selective β-adrenergic blocker (~3:1 β:α IV, ~7:1 PO). BP-lowering without reflex tachycardia. Workhorse for… Oral half-life 4.9 h.
Combined α1 + non-selective β-adrenergic blocker (~3:1 β:α IV, ~7:1 PO). BP-lowering without reflex tachycardia. Workhorse for hypertension in pregnancy + emergency BP control + pheochromocytoma pre-op management.
PK: F 0.18 is verbatim and stands, and V 660 L IS INTRAVENOUS-DERIVED — a steady-state volume of 9.41 L/kg — so pairing the two is CORRECT and was checked before judging; had it been an oral apparent volume, dividing by F again would have inflated it about 5.5-fold. Half-life corrected 6 to the stated 4.9 h. ITS EFFECT-COMPARTMENT VALUE IS REMOVED ON TWO GROUNDS: it was borrowed from a rat single-enantiomer atenolol study under a "class-typical" label that is not a real quantity, and its note claim of "no published keo" is FALSE — this record own cited paper fits an effect compartment and reports a significant correlation, it simply does not print the rate. FOUR STEREOISOMERS SHARE THIS RECORD with different actions: the parent is an alpha-1 antagonist while one isomer, about a quarter of the material, is a beta-2 agonist with negligible alpha affinity. A reference is a paper on alpha-1 AGONISTS in which labetalol, an antagonist, does not appear.
Pharmacokinetics
- Oral — t½ 4.9 h · F 18% · Vd 660 L
- IV — t½ 4.9 h · F 100% · Vd 660 L
Sources: PMID:7203731, PMID:15655528, PMID:1884570, PMID:6370541