The tools for detecting false positives, false negatives, and interference in interactions when testing and monitoring therapeutic drug use

For physicians monitoring a patient's progress, efficacy of treatment is often linked to a patient's response to medication. Determining whether a patient is taking the prescribed amount, the drug or dosage is effective, or the prescribed medication is interacting with other drugs can be determined through drug testing. Written as a guide for toxicologists, chemists, and health professionals involved in patient care,Resolving Erroneous Reports in Toxicology and Therapeutic Drug Monitoring provides an up-to-date introduction to the tests and methodologies used in a toxicology lab as well as the sources of testing error that can lead to false positives, false negatives, and unreliable conclusions of drug abuse or under use.

Covering a host of common therapeutic drugs as well as specific types of interference in immunoassays used in drug testing, the book details a number of possible testing scenarios and problems as well as solutions:

False positive results in immunoassays for drugs in abuse testingInterferences in immunoassays used for monitoring anticonvulsants, tricyclic antidepressants, and digoxinFalse positive alcohol tests using breath analyzers and automated analyzersWhen a toxicology report is negative in a suspected overdose patient: the world of designer drugsEffects of drug-herb interactions on therapeutic drug monitoringPharmacogenomics and the general principles of genetic analysisApproaches for eliminating interference/discordant specimen in therapeutic drug monitoring and drugs in abuse testingWhat to do in case there is no readily available method for testing

Complete with easy-to-read tables and flowcharts, this book helps toxicologists, clinical chemists, clinical pathologists, and forensic pathologists develop accurate, unbiased drug monitoring and toxicology reports. Health care professionals involved in patient care, especially of critically ill patients, will find this guide indispensable in making sure lab tests are reliable enough to provide high-quality care. An indispensable handbook to the entire suite of toxicology lab tests, as well as all the possible sources of testing error,Resolving Erroneous Reports in Toxicology and Therapeutic Drug Monitoring offers clear remedies for eliminating and preventing testing error.

AMITAVA DASGUPTA is a Professor in the Department of Pathology and Laboratory Medicine at the University of Texas Medical School at Houston and the director of clinical chemistry, toxicology, and point of care testing at the Memorial Hermann Hospital. He is the author ofHerbal Supplements andPharmacogenomics in Clinical Therapeutics, both published by Wiley.

Preface vii

Chapter 1 An Introduction to Tests Performed in Toxicology Laboratories 1

Chapter 2 Challenges in Drugs of Abuse Testing 31

Chapter 3 False-Positive Results Using Immunoassays for Drugs of Abuse Testing 53

Chapter 4 True-Positive Drugs of Abuse Test Results Due to Use of Prescriptions and Nonprescription Drugs 67

Chapter 5 When Toxicology Report Is Negative in a Suspected Overdosed Patient:

The World of Designer Drugs 85

Chapter 6 Abuse of Magic Mushrooms, Peyote Cactus, Khat, and Solvents: No Readily Available Laboratory Tests 101

Chapter 7 Limitations of Blood Alcohol Measurements Using Automated Analyzers and Breath Analyzers 121

Chapter 8 Role of the Laboratory in Detecting Other Poisoning, Including Pesticides, Ethylene Glycol, and Methanol 139

Chapter 9 Poisoning with Warfarin and Superwarfarin: What Can Laboratory Testing Do? 161

Chapter 10 Plant Poisoning and the Clinical Laboratory 185

Chapter 11 Sources of Erroneous Results in Therapeutic Drug Monitoring Due to Preanalytical Errors, High Bilirubin, Hemolysis, and Lipids 213

Chapter 12 Challenges in Therapeutic Drug Monitoring of Digoxin Using Immunoassays 237

Chapter 13 Interference in Immunoassays Used for Monitoring Anticonvulsants and the Usefulness of Monitoring Free Anticonvulsants 265

Chapter 14 Interference in Immunoassays Used to Monitor Tricyclic Antidepressants 293

Chapter 15 Therapeutic Drug Monitoring of Immunosuppressants: Limitations of Immunoassays and the Need for Chromatographic Methods 323

Chapter 16 Effect of DrugHerb Interactions on Therapeutic Drug Monitoring 355

Chapter 17 Pharmacogenomics and the Toxicology Laboratory 385

Chapter 18 Approaches for Eliminating Interference/Discordant Specimens in Therapeutic Drug Monitoring and Drugs of Abuse Testing 411

Index 429