Background and Importance Although obesity is a risk factor of inferior health, it has not been conclusively proven to be associated with worse outcomes in haematopoietic stem cell transplantation (HSCT). Despite the insufficient scientific evidence, the American Society for Blood and Marrow Transplantation (ASBMT) consider that some drugs used in conditioning therapy before HSCT may need dose adjustment in obese patients in order to reduce toxicities, such as gastrointestinal and haematologic toxicities.

Aim and Objectives The objective of this study is to assess pharmaceutical interventions of dose drug adjustment in obese patients during hospital admission following the ASBMT recommendations.

Material and Methods Prospective observational study of obese patients receiving HSCT from January 2021 to August 2023. Drugs that required weight dose adjustment were busulfan, etoposide, cyclophosphamide, thiotepa and carmustine. Patients were categorised by body mass index (BMI): normal (<25kg/m2), overweight (25–29.9kg/m2), obese (30–39.9kg/m2) or severely obese (BMI>40kg/m2). Dose adjustment was made when real weightţ >120% of ideal weight and BMI ≥27kg/m2. Pharmaceutical interventions were carried out for a correct drug dosage.

Results 154 adult patients received HSCT in the study period (87 autologous, 67 allogeneic) for haematological diseases. In 77 (50%) patients had been prescribed a chemotherapy drug that required weight dose adjustment, 31.2% (24/77) patients were overweight or obese, so they needed a prescription, pharmaceutical review. Median BMI of these patients were 31 kg/m2 (28–32). Out of these 24 obese patients, 17 (70.8%) medical prescriptions were reviewed and 23 drug doses were modified after pharmaceutical intervention to get an appropriate dose in obese (10 busulfan, 6 thiotepa, 5 carmustine, 2 cyclophosphamide).

Conclusion and Relevance Selecting the optimal dose of conditioning chemotherapy in obese patients is complicated, but the role of the pharmacist is essential to optimise chemotherapy in obese patients receiving HSCT, working with the haematologist in a multidisciplinary team. Further research is necessary to corroborate whether these dose adjustments provide real benefit in reducing toxicity.

Conflict of Interest No conflict of interest.