Validation and Application of a Dried Blood Spot Assay for Biofilm-Active Antibiotics Commonly Used for Treatment of Prosthetic Implant Infections.
Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic (PK)/pharmacodynamic (PD) studies in situations where venous blood sampling is logistically difficult. We sought to develop, validate, and apply a DBS assay for rifampin (RIF), fusidic acid (FUS), and ciprofloxacin (CIP). These antibiotics are considered active against organisms in biofilms and are therefore commonly used for the treatment of infections associated with prosthetic implants. A liquid chromatography-mass spectroscopy DBS assay was developed and validated, including red cell partitioning and thermal stability for each drug and the rifampin metabolite desacetyl rifampin (Des-RIF). Plasma and DBS concentrations in 10 healthy adults were compared, and the concentration-time profiles were incorporated into population PK models. The limits of quantification for RIF, Des-RIF, CIP, and FUS in DBS were 15 μg/liter, 14 μg/liter, 25 μg/liter, and 153 μg/liter, respectively. Adjusting for hematocrit, red cell partitioning, and relative recovery, DBS-predicted plasma concentrations were comparable to measured plasma concentrations for each antibiotic (r > 0.95; P < 0.0001), and Bland-Altman plots showed no significant bias. The final population PK estimates of clearance, volume of distribution, and time above threshold MICs for measured and DBS-predicted plasma concentrations were comparable. These drugs were stable in DBSs for at least 10 days at room temperature and 1 month at 4°C. The present DBS antibiotic assays are robust and can be used as surrogates for plasma concentrations to provide valid PK and PK/PD data in a variety of clinical situations, including therapeutic drug monitoring or studies of implant infections.
Department of Infectious Diseases, Fremantle Hospital, Fremantle, Western Australia, Australia.
Ben
B
Knippenberg
School of Pharmacy, Curtin University, Bentley, Western Australia, Australia.
Madhu
M
Page-Sharp
School of Medicine and Pharmacology, University of Western Australia, Fremantle Hospital, Fremantle, Western Australia, Australia.
Sam
0000-0002-8276-6784
S
Salman
Department of Infectious Diseases, Fremantle Hospital, Fremantle, Western Australia, Australia.
Ben
B
Clark
Department of Infectious Diseases, Fremantle Hospital, Fremantle, Western Australia, Australia.
John
J
Dyer
School of Pharmacy, Curtin University, Bentley, Western Australia, Australia.
Kevin T
KT
Batty
School of Medicine and Pharmacology, University of Western Australia, Fremantle Hospital, Fremantle, Western Australia, Australia.
Timothy M E
TM
Davis
School of Medicine and Pharmacology, University of Western Australia, Harry Perkins Research Institute, Fiona Stanley Hospital, Murdoch, Western Australia, Australia laurens.manning@uwa.edu.au.
Laurens
L
Manning
D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D018441:Biofilms / Q000187:drug effects*; D001681:Biological Assay / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods; D002939:Ciprofloxacin / Q000627:therapeutic use; D059788:Dried Blood Spot Testing / Q000379:methods*; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D005672:Fusidic Acid / Q000627:therapeutic use; D006400:Hematocrit / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants / Q000382:microbiology*; D016459:Prosthesis-Related Infections / Q000188:drug therapy* / Q000382:microbiology*; D015203:Reproducibility of Results; D012293:Rifampin / Q000627:therapeutic use; D053719:Tandem Mass Spectrometry / Q000379:methods
D000900:Anti-Bacterial Agents; D005672:Fusidic Acid; D002939:Ciprofloxacin; D012293:Rifampin