Pick the beta-blocker that SSRIs cannot slow down

The edition in brief

The edition closes on a scoping review of 48 studies of adverse events when beta-blockers and SSRIs are taken together. Bradycardia was the commonest report, mostly with metoprolol or propranolol combined with fluoxetine, paroxetine or sertraline, and the usual proposed mechanism was CYP2D6 inhibition raising beta-blocker levels. The evidence is mostly case reports, but the pharmacology is sound: when an SSRI and a beta-blocker must be combined, a beta-blocker not cleared by CYP2D6, or an SSRI with little CYP2D6 effect, avoids the problem. Data from the IMPAACT 2001 study show rifapentine, given weekly with isoniazid for TB prevention, passes into breast milk at about 2% of maternal plasma levels, with an estimated infant dose under 1%; it crosses the placenta, but infant levels look unlikely to matter. A retrospective study found valproate lowered dose-corrected quetiapine concentrations by about 17%, an effect seen in women but not men. FDA lists a Class II recall of compounded semaglutide syringes from a US pharmacy for lack of sterility assurance. The pearl covers rifampicin's interactions.