REVIEW ARTICLE Drug dosing and monitoring in obese patients undergoing allogenic stem cell transplantation Claudia Langebrake • Friederike Bernhardt • Michael Baehr • Nicolaus Kro ¨ger • Axel R. Zander Received: 10 May 2011 / Accepted: 17 September 2011 / Published online: 29 September 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Background The effects of physiological changes in patients with obesity on pharmacokinetic parameters and the time course of drug response, especially in the field of haematology/oncology, are poorly under- stood. For some antimicrobial drugs, dosing considerations exist, while for cytostatic drugs, dose modifications for obese patients are not consistently recommended. Glo- merular filtration rate and renal perfusion appear to be similar in obese and normal weight individuals, thus elimination of hydrophilic and extensively renally cleared drugs mainly depends upon creatinine clearance. Aim of the review To provide information about drug dosing in mor- bidly obese patients undergoing allogenic haematopoietic stem cell transplantation and to develop dosing recom- mendations for those patients, based on literature data, pharmacokinetic properties and own experiences. Method A review on the literature on drug dosing in obese patients as well as on the pharmacokinetic properties of drugs which are supposed to be used in the field of stem cell transplantation was combined with own data on drug dosing and pharmacokinetic drug monitoring in a morbidly obese patient undergoing matched-unrelated allogenic peripheral blood stem cell transplantation. Results For hydrophilic and extensively renally cleared drugs (e.g. piperacillin/sulbactam, cotrimoxazole, fludarabine) stan- dard dosages for adult patients or dosing based on ideal body weight (IBW) (e.g. aciclovir, methotrexate) can be used. For ciclosporin and digitoxin we could show that high initial doses are needed to achieve sufficient plasma concentrations. After steady state distribution was com- pleted, maintenance doses comparable to normal weight patients are sufficient. Likewise, distribution of enoxaparin and phenytoin seems to take longer in obese patients. Dosing recommendations of 25 drugs that can be used in morbidly obese patients undergoing allogenic stem cell transplantation are given. Conclusions Pharmacotherapy in morbidly obese patients undergoing allogenic stem cell transplantation is possible, if pharmacokinetic properties of the drugs are considered and close monitoring of plasma concentrations is performed. Keywords Drug dosing Á Obesity Á Pharmacokinetics Á Stem cell transplantation Impacts on practice • Only limited data are available about dose adjustments in obesity for the majority of drugs used in the field of haematopoietic stem cell transplantation. • Drug dosing in morbidly obese patients has to take pharmacokinetic drug properties into account. • Close therapeutic drug monitoring and/or clinical monitoring is desirable in obese patients undergoing stem cell transplantation. Introduction Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. A C. Langebrake (&) Á F. Bernhardt Á N. Kro ¨ger Á A. R. Zander Clinic for Stem Cell Transplantation, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany e-mail: c.langebrake@uke.uni-hamburg.de C. Langebrake Á M. Baehr Pharmacy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany 123 Int J Clin Pharm (2011) 33:918–924 DOI 10.1007/s11096-011-9568-0