The edition · Clinical Pharmacology
Measure voriconazole and posaconazole levels routinely; for other antifungals, choose your patients
A review of antifungal TDM sets out where targets are solid and where they are not. Also: most breastfeeding mothers on medicines can keep feeding, one in five patients may carry a genotype that changes a prescription, rifampicin's grip on a long-acting HIV injectable, and an FDA supplement for tucatinib.
The edition in brief
Today's clinical pharmacology edition closes on therapeutic drug monitoring of antifungals. A review through November 2025 found robust support for routine trough monitoring of voriconazole and posaconazole, selective monitoring of isavuconazole in critically ill, paediatric and obese patients or those on extracorporeal therapy, and no routine role yet for echinocandins or amphotericin B. Over five years, the Lyon pharmacovigilance centre answered 2,473 questions about medicines in breastfeeding and supported continued feeding in 87%, with polytherapy linked to more restrictive advice. In a Singapore hospital, 38–43% of patients each year received a medicine with CPIC-level pharmacogenomic guidance, and about 18% could have had a prescription changed by pre-emptive testing. A case report showed rifampicin cut long-acting rilpivirine levels by 83% and cabotegravir by 57% within a week, with recovery after stopping. FDA recorded a supplement to the tucatinib application on 7 October; the record does not specify the change. The pearl explains why enzyme induction outlasts the inducer.
Most breastfeeding questions ended in advice to keep feeding
Most maternal medicines are compatible with breastfeeding; check a lactation resource before advising a mother to stop.
FDA records a supplement to the tucatinib application
Read the updated tucatinib label for the change, and review CYP3A and CYP2C8 interactions whenever it is prescribed.
About one in five patients could have had a prescription changed by genotype
Where a pharmacogenomic result is available, use it for clopidogrel, codeine, tramadol and simvastatin decisions.
Rifampicin cut long-acting rilpivirine levels by 83% in a week
When rifampicin cannot be avoided in a patient on long-acting cabotegravir/rilpivirine, give oral antiretroviral bridging and check levels.
Enzyme induction outlasts the inducer
When stopping an enzyme inducer, plan dose reductions and monitoring for narrow-margin drugs over the following two weeks.
Antifungal TDM: routine for voriconazole and posaconazole, selective for isavuconazole
Measure voriconazole and posaconazole troughs routinely, and consider isavuconazole levels in high-risk patients.
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