Related Experiment Video
Updated: Jun 2, 2026
10:17
High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry
Published on: April 23, 2019
Interferences with urine drug screens.
Charles Herring1, Andrew J Muzyk, Cynthia Johnston
1Campbell University School of Pharmacy and Health Sciences, Buies Creek, NC, USA.
Journal of Pharmacy Practice
|April 22, 2011
Summary
Urine drug tests help monitor patients on opioid therapy for chronic nonmalignant pain (CNMP). Understanding test interferences is crucial for accurate results and safe opioid prescribing.
Area of Science:
- Clinical Chemistry
- Pharmacology
- Pain Management
Background:
- Urine drug assays (UDAs) are vital for monitoring patients on opioid therapy for chronic nonmalignant pain (CNMP).
- These tests, alongside opioid contracts, aid in tracking prescribed and illicit substance use.
- Safe opioid prescribing for CNMP requires understanding UDA limitations.
Purpose of the Study:
- To review the literature on interferences with commonly used urine drug assays.
- To provide practitioners with information on confirming contested urine drug test results.
Main Methods:
- Literature review of urine drug assay interferences.
- Summary of findings on test interferences and confirmation options.
Main Results:
- Common urine drug assays can have interferences affecting results.
- Knowledge of these interferences is essential for clinical decision-making.
- Confirmation methods exist for contested test results.
Conclusions:
- Understanding urine drug assay interferences is critical for safe opioid prescribing in CNMP management.
- Practitioners must be aware of potential false positives/negatives and confirmation strategies.
- Appropriate use of UDAs supports safer management of patients on long-term opioid therapy.
Related Concept Videos
01:22Drug Elimination by Renal Route: Tubular Reabsorption
During the process of renal excretion, as the glomerular filtrate progresses to the distal convoluted tubule (DCT), drugs that are highly permeable, lipophilic, and nonionized undergo passive reabsorption from the tubular fluid into the surrounding peritubular capillaries. This reabsorption process restricts their elimination through the kidneys. However, the majority of drugs are either weak acids or weak bases, and their ionization level is dependent on pH. By altering the pH of urine, the...
01:09Factors Affecting Renal Clearance: Drug Distribution and Drug Interactions
Renal clearance plays a pivotal role in drug elimination from the body and can be influenced by drug distribution and interactions. Understanding these factors is crucial in pharmacology as they impact the effectiveness and duration of drug therapy.
One important factor is the relationship between renal clearance and the apparent volume of distribution. Renal clearance tends to be inversely proportional to the apparent volume of distribution. Drugs with an extensive distribution volume or those...
One important factor is the relationship between renal clearance and the apparent volume of distribution. Renal clearance tends to be inversely proportional to the apparent volume of distribution. Drugs with an extensive distribution volume or those...
01:30Drug toxicity: Drug–Drug Interaction
Drug–drug interactions can precipitate toxicity through multiple mechanisms. Absorption interactions alter how drugs enter the body, exemplified when ranitidine increases the absorption of basic drugs, while cholestyramine decreases the levels of propranolol. Protein binding interactions occur when drugs share the same binding sites on plasma proteins. Drugs like aspirin and warfarin, when bound in excess, can lead to increased free drug concentrations, enhancing the potential for...
01:25Pharmacokinetics: Drug–Drug Interactions
Drug interactions occur when the pharmacological effect of one drug is altered by another substance, either enhancing or diminishing its activity. The drug whose activity is altered is known as the object drug, and the substance causing the alteration is called the agent drug or the precipitant. The net effects of these interactions are mostly undesirable, leading to decreased effectiveness or increased adverse effects. In rare cases, interactions can be beneficial, such as the enhanced...
01:15Drug Elimination by Renal Route: Tubular Secretion
Once the process of glomerular filtration is completed, blood carrying unfiltered drug molecules traverses through efferent arterioles and makes its way into the peritubular capillaries in the proximal tubule. A variety of carriers play a pivotal role in actively secreting drugs from these peritubular capillaries into the tubular fluid. The organic anion transporter transfers acidic drugs, against an electrochemical gradient, from the peritubular capillaries into the renal tubule cells and...
01:26Urine Studies II: Urine Culture and Sensitivity Test
A urine culture and sensitivity test is a diagnostic procedure used to identify urinary tract bacterial infections and determine the most effective antibiotics for treatment. This test is generally preferred when a patient shows manifestations of a urinary tract infection, such as frequent or painful urination, cloudy or foul-smelling urine, or lower abdominal pain.Purpose of the TestThe primary goals of a urine culture and sensitivity test are to:Determine the specific bacteria causing the...