通过头发分析调查的儿童和青少年对滥用药物的暴露

Drug dependence, abuse, and addiction are complex phenomena that can precipitate various abnormal states. Physical dependence refers to a state of pharmacological adaptation to a drug. This adaptation often results in tolerance—a reduced response to the drug after repeated administrations. When the drug use is abruptly stopped, withdrawal symptoms occur due to the body's need to readjust from the pharmacologically induced imbalance. However, tolerance and withdrawal symptoms do not...

Drug excretion involves various organs, including the liver, intestines, skin, and eyes. In the case of drugs or toxins, they can be actively secreted into bile by transporters in the hepatocyte's canalicular membrane. These substances enter the GI tract during digestion and may be reabsorbed into the body from the intestine. This process, known as enterohepatic recycling, can significantly prolong the presence and effects of a substance in the body. To interrupt this cycle, specific...

Drug concentration is the quantity of a drug present in a biological sample. Measuring drug amounts in biological samples allows the clinician to understand how a drug is absorbed, distributed, metabolized, and excreted. Samples can be obtained through invasive or non-invasive methods. Invasive techniques involve surgical or parenteral interventions to gather blood, cerebrospinal fluid, or tissue biopsy. Conversely, non-invasive approaches provide samples like urine, feces, and saliva.
Plasma...

Substance use disorders involve a pattern of using drugs more extensively than intended and continuing use despite harmful consequences. This includes legal substances like alcohol and nicotine, as well as illegal drugs. These disorders often involve both physical and psychological dependence, reflecting compulsive use of substances that significantly alter thoughts, feelings, and behaviors, contributing to a major public health issue.
Understanding the concepts of physical dependence,...

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by persistent inattention, hyperactivity, and impulsivity. It affects approximately 5-8% of children globally, with around 60-70% of cases persisting into adulthood. ADHD has significant implications for educational attainment, social interactions, and occupational success.
Diagnostic Criteria and Symptoms
To diagnose ADHD, symptoms must manifest before age 12 and be evident across multiple settings....

Gaseous substances like general anesthetics are absorbed and excreted through the lungs via simple diffusion. This process depends on factors such as pulmonary blood flow, respiration rate, and the substance's solubility. Gaseous anesthetics like nitrous oxide with low blood solubility are excreted rapidly, while compounds like alcohol, with high blood and tissue solubility, are excreted slowly.
Drugs can also be excreted in breast milk, which is crucial for breastfeeding infants. The...