The edition · Clinical Pharmacology
Medicines while breastfeeding: 87% of five years' pharmacovigilance queries ended with feeding supported
A French pharmacovigilance centre reviewed 2,473 breastfeeding questions. Also: one week of rifampicin cut long-acting rilpivirine below target, lenacapavir held up alongside primidone, pharmacogenomic prescribing in a multi-ethnic Asian population, and where antifungal drug monitoring earns its place.
The edition in brief
Over five years, the Lyon pharmacovigilance centre answered 2,473 questions about medicines during breastfeeding; 87% ended with advice supporting continued breastfeeding, sometimes with monitoring, dose changes or timing, and infant adverse effects were rare and non-serious. Polytherapy, present in 35%, was linked to more restrictive advice. In a man on long-acting cabotegravir/rilpivirine, a week of rifampicin lowered cabotegravir by 57% and rilpivirine by 83%, below target, with recovery within a week of stopping; oral bridging kept the viral load undetectable. In another case, lenacapavir concentrations stayed well above target over six months despite low-dose primidone, a CYP3A inducer. Across 1.16 million patients at a Singapore hospital, about 40% received at least one medicine with actionable pharmacogenomic guidance each year, and an estimated 18.4% might have had a prescription changed by pre-emptive testing; Indian and Malay patients received these medicines younger. A review supports routine monitoring of voriconazole and posaconazole levels, selective monitoring of isavuconazole, and not routinely for echinocandins or amphotericin B. The pearl covers prescribing principles in breastfeeding.
One week of rifampicin pushed long-acting rilpivirine below target; levels recovered within a week of stopping
Rifampicin cut long-acting rilpivirine below target within a week; avoid the combination or bridge with an active oral regimen.
Lenacapavir stayed well above target over six months alongside low-dose primidone
In one patient, low-dose primidone did not push lenacapavir below target; use with caution and monitoring where the combination cannot be avoided.
About 40% of patients in a Singapore hospital received a medicine with actionable pharmacogenomic guidance each year
Pharmacogenomically relevant prescribing is common in a multi-ethnic Asian population; consider gene effects when a common drug fails or harms.
Antifungal drug monitoring: routine for voriconazole and posaconazole, selective for isavuconazole
Monitor voriconazole and posaconazole levels routinely, isavuconazole selectively, and echinocandins and amphotericin B not routinely.
Prescribing for a breastfeeding mother
Choose well-studied, short-acting medicines, limit polytherapy and tell the mother what to watch for in the baby.
In five years of breastfeeding queries to a pharmacovigilance centre, 87% ended with breastfeeding supported
Most medicines a breastfeeding mother needs are compatible with continued feeding; check a lactation reference before advising her to stop.
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