Rifapentine barely reaches breast milk, and hydroxychloroquine's metabolite may track lupus control better than the parent drug

The edition in brief

Pharmacokinetic modelling of the IMPAACT 2001 study of once-weekly isoniazid plus rifapentine in pregnant and postpartum women found breast milk concentrations of rifapentine about 2% of maternal plasma and a relative infant dose under 1%; the drug crosses the placenta at levels unlikely to matter. In 102 Japanese patients with lupus on hydroxychloroquine, CYP2D6 intermediate metabolisers made less of the active metabolite desethylhydroxychloroquine, and higher metabolite levels, not parent drug levels, were associated with low disease activity (adjusted OR 1.80 per SD); discrimination was modest. A review and FAERS analysis of bispecific antibodies in haematological cancers found teclistamab and glofitamab carried the heaviest toxicity and non-relapse mortality signals, mainly infection-driven, and mosunetuzumab the lightest. A case with drug levels showed lenacapavir concentrations stayed therapeutic alongside low-dose primidone, despite a label warning. The FDA lists a Class II recall of compounded tirzepatide syringes for sterility. The pearl covers how slowly enzyme induction wears off.