Dried Blood Spot Measurement: Application in Tacrolimus Monitoring Using Limited Sampling Strategy and Abbreviated Auc Estimation

Abstract

single centre propectively collected outcome results on an early steroid withdrawal, low dose tacrolimus based immunosuppression in low immunologic risk living donor kidney transplantation. Induction therapy consisted of either 2 doses of basiliximab given 4 days apart or 2 doses of daclizumab, 1 mg/kg body wt, given 2 weeks apart. I.v. methylprednisolone 500 mg/day was given for 3 days beginning on day 0. Oral prednisolone was administered at a dose of 30/day for 3 days, 20 mg/day for 3 days, 15 mg/day for 3 days, 10 mg/ day for 3 days and continued on 5.0 mg/day until day 30 post transplant. Tacrolimus was started at a dose of 0.2 mg/kg body wt the night before the transplant, tacrolimus dose was adjuested to maintain the trough level at 8-12 ug/L for the fi rst 3 months, 5-8 ug/L from 3-12 months and 4-6 ug/L onwards. Mycophenolate was given at a dose of 750 mg b.i.d. for the fi rst 3 months and reduced to 500 mg b.i.d. later. Protocol biopsy was performed at day 10 post transplant, all suspected acute rejection episodes were biopsied. The 1-year acute rejection rate, 1-, 5-and 10-years patient and graft survival rates were studied. A total of 210 patients, mean age; 55.3±12.1 years (range 8-78 years), males:female; 136:64 were studied. Diabetes mellitus was the cause of endstage renal disease in 60% of patients. Subclinical rejection was detected in 5% of patients on protocol biopsy but was not treated if there was no rise in serum creatinine. The 1-year biopsy-confi rmed acute rejection and steroid-resistant rejection rates were 10% and 2% respectively. The 1-, 5-, and 10-years death censored graft survival rates were 99%, 95% and 90% respectively. The 1-, 5-and 10-years patient survival rates were 100%, 92% and 85% respectively. De novo diabetes mellitus occurred in 7% of patients at 1-year. 5/210 patients developed malignancy, 4 were PTLDs. In conclusion, early steroid withdrawal, low dose tacrolimus and mycophenolate based immunosuppression with anti-IL2 receptor induction therapy is an effective immunosuppression regimen with minimal complications for living donor kidney transplantation.

Dried blood spot sampling in combination with LC‐MS/MS for quantitative analysis of small molecules

“…Thus, a comparison is recommended as part of the assay method validation. A good correlation between the data from both the DBS and venous blood methods defi nitely provides further confi dence in quantitative analysis (Cheung et al, 2008;Garcia Boy et al, 2008;Hoogtanders et al, 2007;Koal et al, 2005;van der Heijden et al, 2009).…”

“…DBS samples can be promptly taken whenever a concentrationrelated side eff ect appears. The obtained analytical results might lead to a necessary adjustment of dose or dose regimen (Cheung et al, 2008;Wilhelm et al, 2009).…”

“…As listed in Table 1, DBS-LC-MS/MS has been increasingly employed in clinical study and therapeutic drug monitoring for the analysis of a wide spectrum of drug molecules, including antipyretic (Spooner et al, 2009), antitussive (Liang et al, 2009), antimalarial (Burhenne et al, 2008), anticonvulsant (la Marca et al, 2009, antiretroviral (Koal et al, 2005;ter Heine et al, 2008ter Heine et al, , 2009a, immunosuppressant (Cheung et al, 2008;Hoogtanders et al, 2007;Wilhelm et al, 2009), antiepileptic (la Marca et al, 2008b and vinca alkaloids (Damen et al, 2009), and in monitoring drug abuse (Henderson et al, 1997;Garcia Boy et al, 2008). Because DBS samples could be collected by patients themselves or their guardians with minimum training, this opens up the possibilities of collecting clinical pharmacokinetic samples not only from various in-patients, but also from out-patients, especially those from remote areas (Burhenne et al, 2008).…”

Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS

“…In comparison with previously described LC-MS/MS assays to quantify tacrolimus in dried bloods spots [29][30][31][32][33][34]36,39,41,42 , the present assay matches or exceeds their performance in terms of lower limit of quantification, extraction recovery, accuracy and precision while avoiding potentially risky concepts such as one-step protein precipitation procedures and ultra-short chromatography times, which usually give acceptable results during the validation based on blood samples from healthy individuals. However, transplant patients are a highly complex group of patients who have diseases that affect the composition of blood and who take multiple medications.…”

“…After a simple finger stick the patient collects a blood drop on a special filter paper card and after the blood spot has dried, it can be mailed to a central laboratory for analysis of tacrolimus and any other immunosuppressant that the patient may currently be taking. This has become possible due to the development of highly sensitive and specific LC-MS/MS assays for the quantification of tacrolimus and other immunosuppressants in very small blood volumes such as dried blood spots (typically 20 µl of blood) 25,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] . Another advantage is that minimally invasive, low volume sample collection strategies such as dried blood spots greatly facilitate therapeutic drug monitoring and pharmacokinetic studies in small children 28 .…”