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Drugs Testing Book
- Table of Contents
- Introduction
- Immunoassays and Their Screening
- An Overview Regarding the History of Immunoassays
- Basic Immunoassay Principles and Guidelines
- Variety of Immunoassays Used for Illicit Drug Testing Programs for workplaces
- Characteristics of an Immunoassay’s Performance
- Methodology Limitations
- Types and Mechanisms of Interference of Assays
- Sources of Interference
- Immunoassays and Their Application Regarding Workplace Drug Testing Programs
- Cutoff Ranges and Result Interpretation
- Selection and Troubleshooting of Immunoassays
- Summary
- Confirmation via Contemporary and Latest Techniques
- Conventional Confirmatory methods
- Gas Chromatography
- Liquid Chromatography (High Performance)
- Mass Spectrometry
- Basic Theory
- Ionization Of Electrons
- Chemical Ionization
- Full Scan Analysis
- Selected Ion Monitoring
- Quadruple Mass Spectrometer
- Quadruple ion Trap MS
- Modern Method Of Drug Confirmation
- Additional Mass Analyzers
- Time Of Flight – Mass Spectrometers
- Fticr-MS – Fourier Transform Ion Cyclotron Resonance – Mass Spectrometry
- Capillary Electrophoresis
- Summary
- Quality Assurance
- Organization Employee Assistance Programs
- Chain of Custody
- Specimen Collection
- Standard Operation Procedures
- Personnel
- Accessioning/Specimen Processing
- Security
- Internal Proficiency Testing
- External Proficiency Testing
- Inspection
- Initial and Confirmation Testing
- Equipment and Maintenance
- Laboratory Information Management System
- Records
- Specimen Validity Testing
- Quality Assurance Oversight
- Lean Six Sigma
- Summary
- Supervision of Regulated Workplace
- Historical Overview
- The Responses Of Laboratory and Regulatory Agency to the Problem
- US Federal Regulations/Criteria
- Scope of Adulterant/Substitution Products
- The HHS-Certified Laboratories Experience
- Effects of Adulterants on Analytical Tests
- Governmental Responses to the Problem
- Alternate Specimen Matrices
- Summary
- Drugs of Abuse in Hair
- Drug of Abuse in Oral Fluid
- Sweat Testing
- Amphetamines
- Opoids
- Phencyclidine
- Cocaine
- Cannabinoids
- Stability of Drugs of Abuse in Biological Fluids
- Interpretation of Workplace Drug Test Results by Medical Review Officer
- Federal Drug-Testing Programs
- Amphetamines
- Cocaine
- Marijuana
- Opiates
- Phencyclidine
- Other Drugs Tested For in Workplace Programs
- Benzodiazepines
- Barbiturates
- Methadone, Methaqualone, and Propoxyphene
- Ethyl Alcohol
- Dot-Mandated Alcohol Testing
- Specimen Validity Testing
- Additional MRO Functions Under the Federal Drug-Testing Programs
- Summary
- Laboratory Accreditation & Regulation
Drug of Abuse in Oral Fluid
Therapeutic drug monitoring for the oral fluids has been widely used over the decade and has become very popular as supportive or alternative matrix for use in forensic studies, including drug testing at workplace. Generally the process requires that the drug enters through saliva by simple diffusion via cell membranes, usually it require the free drug in nonionized and lipid soluble form. The Equilibrium shows the relationship between the saliva’s drug concentration and its level in plasma which is dependent upon the drug binding to the plasma protein, the pKa of the drug and pH of both matrices. The Henderson-Hasselbach equation can help us to better understand the relationship as follows:
Basic drugs: S/P = ([1+ 10(pKd-pHs)]/[1+10(pKd-pHp)])+(fp/fs)
Acidic drugs: S/P = ([1+ 10(pHs-pKa)]/[1+10(pHp-pKa)])+(fp/fs)
Where S = concentration of drug in Saliva, pHs = pH of saliva, P = concentration of drug in plasma, pHp = pH of plasma, pKd = log of ionization constant for basic drugs, pKa = log of ionization constant for acidic drugs, fp = fraction of drug bound to plasma, and fs = fraction of drug bound to saliva.
The pH ranging from 6.2 to 7.0 has been found for unstimulated saliva on the other side the pH can reach up to 8.0 for stimulated oral fluid collections, affecting the detection of specimen concentration of drug. The free portion (unbound) of the drug in the circulating blood is reflected by the saliva at the time of sampling. The reason for the detection of higher concentrations of weekly basic drugs in saliva than in blood is due to the pH of saliva being lower than that of the plasma. As it quite clear that the amount of free drug circulating in the plasma can be related to the saliva drug concentrations, they may also be correlated to pharmacological effects.
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