Sep 3 2013, 5:14pm CDT | by PR.com
Sun City Center, FL, September 03, 2013 --(PR.com)-- Alprazolam (Xanax) is a short-acting benzodiazepine commonly prescribed for treating panic disorder, anxiety and insomnia. As a benzodiazepine, alprazolam exerts its pharmacological actions by binding to the GABAA receptor in the central nervous system and potentiating its neuroinhibitory effects. Oral alprazolam is extensively metabolized by the human hepatic CYP3A4 to form two less active metabolites, alphahydroxy alprazolam and 4-hydroxyalprazolam. CYP3A4 is the most abundant P450 enzyme in both the human liver and intestine. While variations in metabolic capacity, due to CYP3A4 gene polymorphism, are rare, drug-drug interactions leading to induced or inhibited CYP3A4 enzymatic activities are quite common. Concurrent uses of grapefruit juice or drugs like macrolides and azoles might inadvertently increase alprazolam blood concentration and slow its clearance. Alprazolam and its metabolites are predominantly eliminated through the urinary route. American Clinical Solutions provides testing service for alprazolam and alphahydroxy alprazolam in urine and oral fluid. Detection windows for alprazolam and alphahydroxy alprazolam in urine are about 1-3 days after last exposure. In oral fluid, alprazolam can be detected within 12 hours. For unknown reasons, alprahydroxy alprazolam has been rarely detected in oral fluid. Early research indicated that in urine about 20% of a dose is eliminated as an unchanged drug, and excretion of alphahydroxy alprazolam accounts for 17% of a dose. An internal study conducted by American Clinical Solutions with patients prescribed alprazolam confirmed those findings. Average concentrations of positive (above cutoff value, 50 ng/ml for both) alprazolam and alphahydroxy alprazolam samples were 335 and 447 ng/ml. Detection rate of alphaphydroxy alprazolam was slightly higher than that of alprazolam among patients with the prescription (57.0% versus 49.7%).
Comparable urinary concentration and detection rates between alprazolam and its metabolite suggest that physicians prescribing alprazolam should expect to see both in a patient’s urine sample. A recent national survey suggested that alprazolam is the most commonly abused benzodiazepine . In 2011, there were 123,744 emergency department (ED) visits due to nonmedical use of alprazolam nationwide, which accounted for 9.9% of all ED visits due to nonmedical use of medications  . The true number of alprazolam misuses in the general population might be even higher. The high prevalence of alprazolam misuses and abuses might be due to its pharmacological properties (as a drug with rapid onset of action), easy availability and a false sense of drug safety. Compared to other compounds like alcohol and barbiturates working on GABAA receptors, benzodiazepines are generally considered to have a higher margin of safety. Theoretically, benzodiazepines have a ceiling effect in GABAA-mediated pharmacological actions, and further increasing doses will not lead to heightened CNS depression. Among benzodiazepines, short-acting ones like alprazolam are deemed safer than long-acting ones like diazepam, simply due to their shorter half-lives in the human body. However, concomitant use of alprazolam, with other CNS depressants such as alcohol and opioid analgesics, could have an additive CNS depression effect and lead to severe toxicity or even death. In light of rampant alprazolam misuses and abuses, monitoring alprazolam adherence would be highly advisable for physicians to practice safe and effective medicine.
1. The Substance Abuse and Mental Health Services Administration (SAMHSA). Results from the 2011 National Survey on Drug Use and Health: Summary of National Findings. 2012.
Cheng Fang, MD., PH D., DABT | email@example.com
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