Benchtop nuclear magnetic resonance performance evaluation according to ASTM E691-22 on a population of instruments: Molar substitution determination in hydroxypropyl betadex as a case study for use in quality control environments.

The inclusion of quantitative nuclear magnetic resonance (qNMR) spectroscopy in industry has historically been stifled by a lack of accessibility, caused in-part by the large costs of traditional high-field spectrometers, the maintenance required for these, and the expertise necessary to manage and use them. In recent years, the emergence of benchtop NMR technology, an accessible, affordable, and automatable alternative, has led to a more feasible incorporation of NMR into quality control spaces, an area traditionally reserved for other techniques such as gas chromatography and liquid chromatography, which are routinely combined with detection techniques such as mass spectrometry. While these techniques are commonly used in analyzer-type applications using gold standard methods of analysis, wherein an instrument is dedicated to performing specific assays, this remains uncommon for NMR. Herein, we perform a full method verification using benchtop qNMR on a population of benchtop NMR instruments according to the ASTM designation E691-22, a standard used to determine the precision of a test method. To our knowledge, this is the first published example of this type of study for benchtop NMR spectroscopy. For this work, a total of five analysts performed assays on 23 different benchtop NMR instruments for the analysis of hydroxypropyl betadex according to the USP-NF method, and the results are compared using a variety of statistical methods. The results of this work demonstrate that benchtop NMR technology is effective and robust under repeatability and reproducibility conditions and is a powerful tool for these types of routine quality control analyses.

Resolución Quirúrgica para Un Caso de Polisinusitis de Origen Odontogénico / Surgical Resolution for A Case of Polysinusitis of Odontogenic Origin

La celulitis orbitaria es una patología grave que está asociada con sinusitis paranasal. Éstas suelen presentar edema periorbitario, dolor, y movimiento extraocular restringido. La mayoría de los casos presentan pronóstico favorable, asociado a terapia antibiótica o drenaje quirúrgico. Las celulitis de origen odontogénico representan 2 a 5 % de todos los casos; se caracterizan por una diseminación del proceso infeccioso desde los ápices de las raíces, infectando al seno maxilar, llegando a la órbita a través de la fisura orbitaria inferior o a través de un defecto en el piso de la órbita. En el presente estudio se reporta el caso de un paciente masculino de 28 años que consulta por aumento de volumen periorbitario izquierdo con 4 días de evolución, posterior a exodoncia de segundo molar superior izquierdo. Al examen extraoral presenta aumento de volumen izquierdo con eritema periorbitario, proptosis ocular ipsilateral con visión conservada, y salida de líquido purulento por fosa nasal izquierda. En los exámenes de laboratorio e imagenológicos se pesquisa compromiso de seno maxilar, etmoidal y esfenoidal, decidiendo su hospitalización y manejo quirúrgico en tres tiempos operatorios, los cuales permiten acceso a pared anterior del seno maxilar y a espacio pterigoideo. Dentro de los diagnósticos de celulitis orbitaria pueden incluir reacciones alérgicas, conjuntivitis o herpes. Se excluyeron los diagnósticos mencionados debido a que no se observaron alteraciones dermocutáneas periorbitarias. Por el contrario, el compromiso unilateral, movimiento ocular alterado y doloroso indica que el cuadro abarcaba espacios profundos. La infección de senos paranasales posterior a una exodoncia es una complicación poco frecuente. Un diagnóstico temprano adecuado disminuye la morbilidad y mortalidad de esta condición. Debemos estar alertas a complicaciones posteriores en procedimientos realizados, tener conocimiento en diagnóstico y manejo de posibles evoluciones tórpidas en pacientes.

Orbital cellulitis is a serious pathology that is associated with paranasal sinusitis. These medical conditions usually present with periorbital edema, pain, and restricted extraocular movement. Most cases have a favorable prognosis, associated with antibiotic therapy or surgical drainage. Cellulitis of odontogenic origin represents 2 to 5 % of all cases. They are characterized by a spread of the infectious process from the apices of the roots, infecting the maxillary sinus, reaching the orbit through the inferior orbital fissure or through a defect in the floor of the orbit. The present study reports the case of a 28-year-old male patient, who consulted for a volume increase in left periorbital volume with 4 days of evolution, after extraction of the upper left second molar. Extraoral examination showed left volume increase with periorbital erythema, ipsilateral ocular proptosis with preserved vision, and discharge of purulent fluid from the left nostril. The laboratory and imaging tests showed compromise of the maxillary, ethmoid and sphenoid sinus deciding on hospitalization and surgical management in three operative times, which allow access to the anterior wall of the maxillary sinus and the pterygoid space. Diagnoses of orbital cellulitis may include allergic reactions, conjunctivitis, or herpes. These diagnoses were excluded because no periorbital dermocutaneous alterations were observed. In contrast, unilateral involvement, impaired eye movement, and pain indicate that the condition involved deep spaces. Paranasal sinus infection after tooth extraction is a rare complication. An early diagnosis adequately decreases the morbidity and mortality of this condition. We must be alert to subsequent complications in procedures performed, have knowledge in diagnosis and management of possible torpid evolutions in patients.

Determination of copolymer compositions in polyhydroxyalkanoates using 1H benchtop nuclear magnetic resonance spectroscopy.

Continuous research into polyhydroxyalkanoates (PHAs), biodegradable polymers which can be produced by, and harvested from, various bacteria has led to more cost-effective ways of isolating and commercializing them. As bio-based polymers, PHAs can be transformed into compostable bioplastics and utilized for a variety of applications. Often isolated as copolymers, the monomeric ratio compositions of these products greatly affect both the properties and consequently, possible end uses of these products. As such, methods of reliably characterizing these ratios are important for quality control and product development purposes. Herein, we discuss how 1H benchtop nuclear magnetic resonance (NMR) instruments can be used for the determination of monomeric ratio compositions in PHAs and compare results obtained at three different NMR field strengths: 1.40 T (60 MHz), 2.35 T (100 MHz), and 9.4 T (400 MHz).

Identification of seven psychedelic 2,5-dimethoxy-phenylethyl-amine-based designer drugs via benchtop 1 H nuclear magnetic resonance spectroscopy.

The dissemination of spectral information of new psychoactive substances (NPS) acquired on benchtop nuclear magnetic resonance (NMR) spectrometers is of high importance considering the emerging application of such portable and accessible instruments in forensic analyses. Seven members of the 2C-X series (2C-B, 2C-C, 2C-D, 2C-E, 2C-P, 2C-T2, and 2C-T7) of NPS were analyzed via 60 MHz 1 H benchtop NMR spectroscopy and their molecular structural relations are discussed with respect to the observed proton NMR spectra.

3,4-Methylenedioxymethamphetamine quantification via benchtop 1H qNMR spectroscopy: Method validation and its application to ecstasy tablets collected at music festivals.

We describe a method validation for the quantification of 3,4-methylenedioxymethamphetamine (MDMA) in tablets based on the United Nations Office on Drugs and Crime (UNODC) guideline for quantitative Nuclear Magnetic Resonance analysis (qNMR). qNMR experiments were carried out on a 60 MHz benchtop NMR spectrometer employing ethylene carbonate as an internal calibrant. A series of 'ecstasy' tablets seized at music events were quantified and the results discussed regarding their within-batch variation and yearly median dose. The method showed good specificity and selectivity, with linearity, precision, accuracy, and recovery well within the UNODC recommended criteria. The limit of detection and quantification are 0.33 mg/mL and 0.10 mg/mL respectively, proving the method works well on small amounts of MDMA. Overall, the lowest amount of MDMA free base detected in this study was 9.35 mg in a piperazine mix, while the highest dosed tablet contained 237.55 mg MDMA free base, with a 9.1% decrease in median amount compared to the pre-pandemic data (2019), but still higher than the data collected in a previous study (105 mg median amount of MDMA free base in 2018). The within-batch variation was insignificant for one of the seizures but showed greater variation for the other, which confirmed that the MDMA content of a single tablet may not reflect that of the whole batch. This dynamic upward change in tablet dosage highlights the importance of ongoing trend monitoring and specific prevention intervention to counteract the negative consequences associated with MDMA use. Benchtop NMR has been successfully employed in quality control, material science and more recently, drug analysis. The present study demonstrates its beneficial application in forensic science overcoming the limitations of currently available instruments and techniques employed in harm reduction and field testing.

Lithium-7 qNMR as a method to quantify lithium content in brines using benchtop NMR.

A novel 7Li quantitative NMR (qNMR) method to analyze lithium was developed to determine the lithium content in real brine samples using benchtop NMR instruments. The method was validated, and limits of detection and quantification of 40 and 100 ppm, respectively, were determined. Linearity, precision, and bias were also experimentally determined, and the results are presented herein. The results were compared to those obtained using atomic absorption (AA) spectroscopy, currently one of the few validated methods for the quantification of lithium. The method provides both accurate and precise results, as well as excellent correlation with AA. The absence of matrix effects, combined with no need for sample preparation or deuterated solvents, shows potential applicability in the mining industry.

Quantitative analysis of cannabinoids using benchtop NMR instruments.

The quantification of cannabinoids is an essential part of cannabis profiling and testing, whether for medical or recreational use. As regulatory bodies continue to increase testing requirements for these products, it is crucial that alternative and effective analytical methods be developed. Herein, we describe the use of benchtop NMR instruments for the quantification of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in a variety of cannabis concentrates and compare the values to those obtained using HPLC, the most common approach for the quantification of cannabinoids. Based on the discrepancies observed in test values from different laboratories using only HPLC, the value of orthogonal testing methods has been identified and is increasingly desired.

Prevalence of Marijuana Use among University Students in Bolivia, Colombia, Ecuador, and Peru.

Young adults 18 to 25 years old show the highest prevalence of marijuana use in Latin America. This study analyzes the changes in prevalence of marijuana use among university students in the Andean Community (Bolivia, Colombia, Ecuador, and Peru) from two studies carried out in 2009 and in 2012. Data were collected through representative two-stage samples of universities and students in the Andean Community. An online survey was administered using a standardized questionnaire. Prevalence was calculated for lifetime, past year, and past month. Marijuana was the most widely used illicit substance consumed among university students, in 2009 and in 2012. Past month prevalence among university students in 2009 in Colombia was 5.27%, in Peru 1.00%, in Ecuador 1.68%, and in Bolivia 0.76%. Past month prevalence in 2012 in Colombia was 7.14%, in Ecuador 3.67%, in Peru 1.62%, and in Bolivia 1.45% in 2012. Among university students in the Andean Community, past month prevalence increased among both males and females between 2009 and 2012 in most countries. Marijuana continues to be the most commonly used illicit drug in Latin American countries. Increases in prevalence among young adults could have important implications for national drug policy.

BN-Dibenzo[a,o]picenes: analogues of an unknown polycyclic aromatic hydrocarbon.

Reflecting on synthetic pinnacles: Whereas the parent hydrocarbon is not readily accessible, several examples of BN substituted-dibenzo[a,o]picenes can be prepared in two steps from known starting materials. These non-linear heptacene analogues are water-stable materials. Their preparation utilizes a potentially general method for preparing extended BN analogues of difficult-to-synthesize polycyclic aromatic hydrocarbon frameworks.

Caracterización de parámetros clínicos y anatomopatológicos de pacientes con cáncer de próstata localmente avanzado en Hospital Barros Luco Trudeau / Characterization of clinical and pathological parameters of patients with locally advanced prostate cancer in Hospital Barros Luco Trudeaus

La estadificación clínica del Cáncer de Próstata es una evaluación de la extensión de la enfermedad mediante el uso de parámetros previos al tratamiento como tacto rectal, PSA, biopsia transrectal e imágenes radiológicas. El estadío anatomo patológico post quirúrgico comprende el análisis histopatológico de la pieza operatoria, lo que constituye una estimación más precisa de la extensión de la enfermedad y representa el método más ¬ fiable para predecir el resultado del tratamiento. De 386 pacientes sometidos a Prostatectomía entre los años 2002 y 2012 se realiza estudio retrospectivo de 48 pacientes, que presentaron compromiso extra prostático. Análisis estadístico de las variables estudiadas mediante prueba de Chi cuadrado. De 386 pacientes sometidos a Prostatectomía, el 12,4 por ciento presentó compromiso extra prostático. La edad promedio fue de 64,1 años; el PSA promedio 12,2 ng/ml. El 37,77 por ciento presentaba un tacto rectal sospechoso. El tamaño prostático promedio estimado por ecografía fue 38,2 cc. La biopsia defi¬nitiva reveló un volumen glandular promedio de 64 cc. y volumen tumoral promedio de 6,9 cc. El 72,92 por ciento fue clasi¬ficado con un score de Gleason 7. El 82 por ciento presentaba compromiso glandular bilateral. El 65,12 por ciento presentó compromiso capsular; 73,9 por ciento compromiso de bordes quirúrgicos; 23,4 por ciento compromiso unilateral y 19,1 por ciento bilateral de vesículas seminales. No fue posible establecer evidencia que permita afirmar la existencia de algún factor predictor para el compromiso capsular, de bordes quirúrgicos, de vesículas seminales, de conductos deferentes, ni permeación linfática. Se logró establecer una relación estadísticamente significativa entre niveles de PSA y probabilidad de compromiso vascular.

Clinical staging of prostate cancer is an assessment of the extent of disease by using pretreatment parameters as DRE, PSA, transrectal biopsy and scans. The postoperative pathologic stage comprises histopathological analysis of surgical piece, which is a more accurate estimate of the extent of disease and represents the most reliable method to predict the outcome of treatment. Retrospective study of 48 patients with prostate cancer who underwent radical prostatectomy between 2002 and 2012, which showed extraprostatic commitment. Statistical analysis of the variables using chi-square test. Of 386 patients undergoing prostatectomy, 12.4 percent had extraprostatic commitment. The average age was 64.1 years and the mean PSA 12.2 ng / ml. The 37.77 percent had a suspicious DRE. The average prostate size estimated by ultrasound was 38.2 cc. The ¬ final biopsy revealed an average volume of 64 cc glandular. and average tumor volume of 6.9 cc. The 72.92 percent was classified with a Gleason score 7. 82 percent had bilateral glandular involvement. The capsular involvement showed 65.12 percent, 73.9 percent commitment surgical margins, 23.4 percent and 19.1 percent unilateral commitment bilateral seminal vesicles. It was not possible to establish evidence to a rm the existence of a predictor factor for capsular involvement of surgical margins, seminal vesicle, vas deferens, or lymphatic permeation. They managed to establish a statistically significant relationship between PSA levels and probability of vascular compromise.

Photochemical synthesis of a ladder diborole: a new boron-containing conjugate material.

Climbing the ladder: Reductive cyclization of alkynyl haloboranes lead to the bis-benzocycloborabutylidene rather than the expected ladder diborole, despite the former being much less thermodynamically favored. Photochemical conversion to the ladder diborole was, however, quite facile upon irradiation at 254 nm.

Test de Tolerancia a la Glucosa para diagnóstico de Diabetes Mellitus tipo 2 y sus estadios previos, experiencia de un Centro de Salud Primaria de Chile: Estudio preliminar / Test of Glucose Tolerance for diagnosis of type 2 Diabetes Mellitus and its previous stages, experience of a Primary Health Center of Chile: Preliminary study

El objetivo de este estudio fue caracterizar a los pacientes con sospecha de diabetes mellitus tipo 2 con glicemia en ayunas previa menor a 126 mg/dl diagnosticados precozmente a través del test de tolerancia a la glucosa. Se realizó un estudio descriptivo transversal, en el Centro de Salud Familiar Violeta Parra de Chillán-Chile. La población estudiada fueron los pacientes con glicemias en ayuno menores de 126 mg/dl, que ingresaron al monitoreo de sospecha de diabetes mellitus tipo 2, a los cuales se les realizó el test de tolerancia oral a la glucosa. Se realizó la revisión de los registros de pacientes que ingresaron entre julio y diciembre de 2011 a monitoreo para diagnóstico de diabetes mellitus tipo 2. Las principales medidas del estudio fueron la frecuencia de diagnóstico de diabetes mellitus tipo 2 y de los estadios pre-diabéticos. Se usó estadística descriptiva para el análisis de los datos, de 364 registros de pacientes en monitoreo, se excluyeron 61 por haber sido ingresados al monitoreo sin test de glicemia en ayunas, de los 303 pacientes con registros adecuados, a 49 (16, 1%) se les diagnosticó diabetes mellitus tipo 2, de éstos 14(4,6%) habían presentado glicemia en ayunas de 110 mg/dl o menos, 176 (58%) pacientes presentaron alteraciones pre-diabéticas y 89 (29,3%) pacientes no presentaron alteraciones. Un alto porcentaje que no sería diagnosticado como diabetes mellitus tipo 2 logra serlo a través del test de tolerancia a la glucosa, lo que justifica la realización del mismo.

The Objective of this study was to characterize patients with suspected diabetes mellitus type 2 with fasting glucose less prior to 126mg/dl diagnosed early through the test of glucose tolerance.We did a cross sectio-nal study in the Family Health Center Violeta Parra de Chillan, Chile. The populations studied were patients with fasting blood glucose less than 126mg/dl, who entered the monitoring of suspected diabetes mellitus 2, to which test they performed oral glucose tolerance. A revision of the records of patients admitted from July to December 2011 monitoring for diagnosis of type 2 diabetes mellitus.The main measures of the study were the frequency of diagnosis of type 2 diabetes mellitus and other pre diabetic stage. Descriptive statistics were used to analyze the data. Of 364 patient records 61 were exclused for being admitted to monitoring blood glucose test without fasting. Of the 303 patients with adequate records, 49 (16.1%) were diagnosed with type 2 diabetes mellitus, of these 14 (4.6%) had fasting glucose of 110mg/dL or less. Pre-diabetes abnormalities had 176 (58%) patients. Only 89 (29.3%) patients showed no abnormalities. A high percentage would not be diagnosed as type 2 diabetes mellitus be achieved through the test of glucose tolerance, which justifies the realization.

Tratamiento con altas dosis de corticoides de Púrpura Trombocitopénica Inmune en paciente con Diabetes Mellitus y Obesidad Mórbida, un desafío metabólico / Treatment of Inmune Thrombocytopenic Purpura whit high doses of steroids in patients with Diabetes Mellitus and Morbid Obesity, a metabolic challenge

El manejo de la púrpura trombocitopénica inmune con altas dosis de corticoides en pacientes con diabetes mellitus y obesidad mórbida no está definido. Mujer de 64 años con obesidad mórbida, diabetes mellitus 2 y púrpura trombocitopénico inmune presenta trombocitopenia severa de 2 000 plaquetas asociada a equimosis extensas en ambas extremidades inferiores y glicemia descompensada. Se inició tratamiento con Metilprednisolona 500mg por tres días y luego Prednisona 60mg/día, al quinto día se aumentó dosis a 1 1 0mg/día. Se usó Metformina (850mg, tres veces al día), insulina NPH e insulina cristalina, logrando pasar de una glicemia capilar promedio de 322mg/ dl (primer día) a 122mg/dl (decimotercer día). Al decimocuarto día, con 86 000 plaquetas, fue dada de alta con tratamiento vía oral y control en policlínico. Se logró compensación metabólica con altas dosis de insulina NPH y Metformina. Es posible usar altas dosis de corticoides en pacientes con diabetes mellitus 2 y obesidad mórbida.

The immune thrombocytopenic purpura management with high doses of corticosteroids in patients with diabetes mellitus and morbid obesity is not defined.A 64 years old woman with morbid obesity, type 2 diabetes mellitus and immune thrombocytopenic purpura, presents sever thrombocytopenia with 2000 platelets, associated to extensive bruising in both legs and decompensate glucose. It was treated with Methylprednisolone 500 mg for three days and then Prednisone 60 mg/day, at the fifth day the dose was increased to 110 mg/day. Metformin was used (859 mg/ three times daily), NPH insulin and crystalline insulin achieving an average capillary glycemia of 322 mg/dl (first day) and 122 mg/dl (thirteenth day). At the fourteenth day with a recount of 86000 platelets she was discharged with oral treatment and clinical control. Metabolic compensation was achieved with high doses of NPH insulin and Metformin. It is possible to use high doses of corticosteroids in patients with type 2 diabetes mellitus and morbid obesity.

Prevalencia del consumo de sustancias psicoactivas en pacientes no psiquiátricos que consultan un servicio de urgencias en Bogotá / Prevalence of Psychoactive Substance Use in Non-Psychiatric Patients Seen at an Emergency Department in Bogotá

Introducción: El consumo de sustancias psicoactivas (SPA) es un problema mundial de Salud pública. Los consumidores suelen utilizar los servicios de urgencias, más que los no Consumidores. Objetivo: Determinar la prevalencia de consumo de seis sustancias psicoactivas en personas entre 18 y 65 años, que acudieron al servicio de urgencias de un hospital Universitario en Bogotá e identificar sus características demográficas. Método: Estudio De corte transversal, con muestreo estratificado por grupos de edad y sexo de pacientes Adultos que acudieron al servicio de urgencias por patologías no psiquiátricas, a quienes Se les aplicó un instrumento que indagaba datos demográficos, médicos, farmacológicos y Toxicológicos. Luego se realizó un análisis toxicológico con el Breath Scan Test, para la detección de alcohol a partir de la exhalación de aire, y el Screeners KO, para la detección en orina de cannabinoides, cocaína, benzodiacepinas, anfetaminas y opiáceos, en las últimas Seis horas. Resultados: Se realizó el análisis en 473 personas. La prevalencia de consumo De cualquier sustancia fue de 7,8%. La sustancia más detectada fue opiáceos, seguida por Alcohol, cannabis, cocaína, benzodiacepinas y anfetaminas. El reporte verbal de consumon las últimas seis horas sólo fue veraz para alcohol. Conclusiones: La prevalencia de Consumo de SPA en la población general de urgencias es alta. De acuerdo con los Resultados, ocho de cada cien personas que consultan a urgencias han consumido alguna SPA en las últimas seis horas...

Introduction: Psychoactive substance abuse is a world public health problem. Drug users tend to use emergency services more than non-users. Objective: To determine the prevalence and demographic characteristics of the use of six substances in people between the ages of 18 and 65, seen at the emergency department of a teaching hospital in Bogotá. Method: Cross sectional study with stratified sampling by age and gender groups of adult patients who were seen at the emergency department (ED). Data collected included demographic, medical, pharmacological, and toxicological information. Toxicological analysis was performed with Scan Breath Test to detect alcohol and KO Screeners to screen urine for use of cannabinoids, cocaine, enzodiazepines, amphetamines, and opiates in the last six hours. Results: Analyses were performed in 473 patients. The prevalence of any substance was 7.8%. The substance most frequently detected was opiates, followed by alcohol, cannabis, cocaine, benzodiazepines, and amphetamines. Conclusions: The prevalence of psychoactive drug use in the general population of the ED is high. According to these results, 8 of out of 100 people who use emergency services have used a psychoactive Substance in the last six hours. The prevalence of self-report was very low compared with The positive results of the toxicology tests...

Tobacco, alcohol, and illicit drug use in adolescents with diabetes mellitus.

BACKGROUND: Substance abuse in adolescents with diabetes mellitus (DM) is associated with the development of acute and chronic complications. OBJECTIVE: To determine the prevalence of alcohol, tobacco, and illicit drug consumption in adolescents with DM and compare it with the prevalence in a large contemporary control (C) group. METHODS: Adolescents with and without DM, who were attending 8th-12th grades, answered a structured written questionnaire, which evaluates the voluntary declaration of tobacco, alcohol, and illicit drug consumption. Subjects with DM were recruited from free diabetes camps or public hospitals (n = 193). The C group was obtained from a nationwide study of prevalence of substance abuse (n = 58,489). For illicit drugs (marijuana, cocaine, or cocaine sulfate), results are shown as life prevalence (ever used the substance). For alcohol and tobacco, results are shown as last month prevalence (the substance was used during the last month). RESULTS: Adolescents with DM showed a lower last month prevalence of tobacco and alcohol consumption than C (27.7 vs. 39.0%, p < 0.01 and 30.1 vs. 39.2%, p < 0.01, respectively). DM group had a lower life prevalence rate of illicit drugs than C group (9.6 vs. 22.2%, respectively; p < 0.01). A lower prevalence of tobacco, alcohol, and illicit drug use in DM group compared with C group was observed in grades 8, 9, and 10. However, a similar frequency of consumption was observed in 11th and 12th grades. CONCLUSION: Compared with healthy youth, DM patients use less tobacco, alcohol, and illicit drugs during the first years of adolescence but not later.

Consumo de drogas en población escolar de Chile en alumnos de 8° básico a 4° medio, 2003 / Drug use in chilean school population ranging from 8th grade basic education to 4th year middle school, 2003

Se describe el consumo de drogas en población escolar chilena que en 2003 cursaba entre el 8° básico y el 4° año medio. Los datos corresponden al Quinto Estudio Nacional de Drogas en Población Escolar de Chile, 2003. Se determinó que la tasa de consumo reciente de cualquier droga ilícita para el grupo de estudio es de 13,66 por ciento, donde el 94 por ciento se concentra en estudiantes que usan marihuana. La tasa de consumo reciente de alcohol y cigarrillos alcanza a 61,15 por ciento y 51,54 por ciento, respectivamente. Los hombres presentan consumos recientes de drogas ilícitas más altos que las mujeres, aunque sólo las superan en 3 puntos porcentuales en marihuana; sin embargo, los usos recientes de pasta base y de cocaína se encuentran en una razón de 2:1. La tendencia del consumo en el bienio 2001-2003, de acuerdo a la prevalencia de último año, registra una disminución del consumo de marihuana y cigarrillos. La disponibilidad de drogas y la baja percepción de riesgo favorece el uso de estas sustancias.