Propylthiouracil
Propylthiouracil. Thionamide antithyroid — same TPO inhibition as methimazole + additional inhibition of peripheral T4→T3 conversion. Preferred… Oral half-life 1.3 h.
Thionamide antithyroid — same TPO inhibition as methimazole + additional inhibition of peripheral T4→T3 conversion. Preferred over methimazole in first-trimester pregnancy (lower teratogen risk) and in thyroid storm. Hepatotoxicity warning at high doses.
PK: the half-life of 1.5 h is the exact MIDPOINT of a review "half-life of 1 to 2 hours", and the cited primary says only that half-lives were unchanged by surgery, giving no number; the measured value of 75 minutes now replaces it. V 30 L is real but belongs to that review, not to the cited paper — whose only volume sentence is about AMPICILLIN, the other drug in the study — and it is re-attributed under label provenance. A TRAP IS LOGGED SO A FUTURE PASS DOES NOT REVERSE THIS CORRECTLY-STORED VALUE: F 0.8 is genuinely a bioavailability, verbatim, but the same review states the drug is "about 80% protein-bound" — the exact coincidence that has produced four protein-binding-read-as-bioavailability errors elsewhere in this audit. This one is correct. Its population is intestinal-bypass patients, which is recorded. ka 1 is dropped, and no scalar is defensible: absorption rate is about three times higher in younger than elderly subjects. THE EFFECT IS PROFOUNDLY DECOUPLED and its own reference says so: the drug is "concentrated in the thyroid gland, exerting an effect on intrathyroidal iodine metabolism for periods exceeding those in which serum concentrations can be measured", rate-limited by turnover of stored hormone over weeks.
Pharmacokinetics
- Oral — t½ 1.3 h · F 80% · Vd 30 L
Sources: PMID:6713763, PMID:6172233, PMID:6688911