Impact of nasogastric administration using the simple suspension method on serum tirabrutinib levels: A case report.
Hideaki Yashima, Takuya Araki, Akiko Kaneta et al.
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Case in brief
An 82-year-old man with relapsed primary central nervous system lymphoma began tirabrutinib at 320 mg/day while fasting. As dysphagia progressed, administration changed from swallowing tablets to nasogastric delivery by the simple suspension method. Serum tirabrutinib measured 11 hours after dosing was 83.2 ng/mL with oral administration and 191 ng/mL with nasogastric administration; dose, concomitant medications, and sampling conditions were consistent. A suspected drug-related rash led to discontinuation on day 19. The nasogastric concentration was not markedly above a previously reported mean 12-hour concentration of around 120 ng/mL, and excessive exposure was considered unlikely to explain the rash.
What made this case unusual
In this patient, nasogastric administration by the simple suspension method was associated with a more than 2-fold higher serum tirabrutinib concentration than oral tablet administration under otherwise consistent conditions.
Diagnostic / clinical pearl
When dysphagia necessitates nasogastric tirabrutinib administration by the simple suspension method, serum concentrations may increase; monitor clinically and consider therapeutic drug monitoring in select cases.
Why it matters
The concentration difference may reflect improved dispersion and absorption, but changes in absorption rate or inter-individual variability cannot be excluded. Further cases and pharmacokinetic investigations are needed.