The Clinical Pharmacokinetics Research Laboratory is specialized in the areas of pharmacokinetics (PK), pharmacodynamics (PD), and therapeutic drug monitoring (TDM). Located at the Kingston Campus of the University of Rhode Island, this lab is equipped with High Performance Liquid Chromatography (HPLC-UV, Hitachi) and LC-Tandem Mass Spectrometry (LC-MS/MS, Applied Biosystems) and a range of other instruments through RI-INBRE centralized core facility. We have established and validated analytical methods for determination of immunosuppressants (i.e. cyclosporine, tacrolimus, sirolimus and mycophenolic acid) and other medications (see the list below). In addition, we specialize in the measurement of free (unbound) drug concentration either in plasma or oral fluids (saliva) and have established methods for determination of contrast media agents, iohexol or iodixanol, useful for accurate estimation of Glomerular Filtration Rate (GFR).

Concentration of total drug and metabolites
Acetaminophen concentration for determination of gastric emptying time (HPLC)
Acetaminophen glucuronide and sulfate metabolites (under development)
Atorvastatin and metabolites [atorvastatin (ATV) lactone, o-hydroxy ATV, o-hydroxy ATV lactone, p-pydroxy ATV, p-hydroxy ATV lactone] (LC-MS/MS)
Cortisol metabolite (6 beta hydroxy cortisol) and free cortisol concentration in urine (under development)
Cyclosporine; total concentration (LC-MS/MS)
Iodixanol concentration for determination of GFR (HPLC)
Iohexol concentration for determination GFR (HPLC)
Midazolam and OH-midazolam (LC-MS/MS) (under development)
Mycophenolic acid (MPA) metabolites; concentration of MPAG and Acyl MPAG (HPLC)
Mycophenolic acid (MPA), total concentration (HPLC)
Oseltimivir and oseltimivir carboxylate (LC-MS/MS)
Prednisolone, prednisone and cortisol concentrations (HPLC)
Tacrolimus; total concentration (LC-MS/MS)
Thyroid hormones, T3 and T4 (LC-MS/MS and ICP-mass spcet)

Unbound (free) concentration of drugs
Cyclosporine; unbound concentration (equilibrium dialysis using [3H] cyclosporine as tracer)
Mycophenolic acid, unbound concentration (ultrafiltration followed by LC-MS/MS)
Tacrolimus; unbound concentration (equilibrium dialysis using [3H]tacrolimus as tracer)

Concentration of drugs in saliva
Cyclosporine; saliva concentration (LC-MS/MS)
Mycophenolic acid, saliva concentration (LC-MS/MS)

Pharmacodynamic assays for immunosuppressive agents

Measurement of inosine 5'-monophosphate dehydrogenase (IMPDH) catalytic activity in peripheral blood mononuclear cells (a marker for mycophenolic acid activity; enzymatic reaction followed by HPLC)

Measurement of intracellular cytokines (IL-2, TNF-alpha, IFN-gamma) expression in mitogen stimulated CD3+ cells (intracellular immunostaining of whole blood followed by flow cytometer)

B-lymphocyte (CD19+) phenotypic markers (CD54, CD86 and CD95) expression on mitogen stimulated peripheral blood mononuclear cells (immunostaining followed by flow cytometer)

ImmuKnow™ test (Cylex Inc): this test detects cell-mediated immunity by measuring the concentration of ATP from CD4+ cells following stimulation.

Preclinical studies

Evaluation of drug metabolism using primary human hepatocyte culture.

Pharmacokinetics and drug-drug interaction studies in rat.

Isolation and fractionation of lipoproteins from plasma to access plasma distribution of drugs among lipoprotein fraction.

Protein binding studies of new drugs and binding of drugs to different blood cells (i.e. red blood cells and lymphocytes).

Transwell assay using MDCK cell lines transfected with human MDR1 (P-glycoprotein) or MRP2 (cMOAT) genes. This assay is employed to characterize drug-drug interaction at transporter level.

 

Other methods

Design of protocols for pharmacokinetic studies
Analysis of data from conventional pharmacokinetic studies (WinNonlin software)
Analysis of population pharmacokinetics data (NONMEM software)