RESUMEN
The identification of the metabolite demoxepam in human urine establishes that chlordiazepoxide, a common benzodiazepine, has been administered. Like N-oxide metabolites of other drugs, demoxepam cannot be detected by gas chromatography-mass spectrometry (GC-MS), due to thermal decomposition, and the product, nordiazepam, is a metabolite common to many benzodiazepines. Demoxepam can be readily screened using a high-performance liquid chromatography (HPLC) system such as REMEDi HS; at 35 degrees C, no thermal decomposition will occur. Currently, there is no confirmation method available for the detection of demoxepam in urine samples. In this study, we demonstrated that following collection of the HPLC fraction, demoxepam can be confirmed using the technique of direct-probe MS. The mass spectra of demoxepam and nordiazepam differ and are easily distinguishable from each other. Ten urine samples that were analyzed by HPLC and determined to contain demoxepam were evaluated; demoxepam was confirmed in each case by direct-probe MS.
Asunto(s)
Ansiolíticos/orina , Benzodiazepinas , Benzodiazepinonas/orina , Espectrometría de Masas/métodos , Ansiolíticos/química , Benzodiazepinonas/química , Biotransformación , Clordiazepóxido/análisis , Clordiazepóxido/química , Cromatografía Líquida de Alta Presión , Cromatografía de Gases y Espectrometría de Masas , Humanos , InmunoensayoRESUMEN
Our institute serves as a centralized clinical laboratory for municipal and private hospitals in Taipei, a major international metropolis in the Asian region. Two key considerations leading to the development of our toxicology program are: a large number of foreign visitors and local residents returning from overseas trips may bring in chemicals which are less commonly seen in this region; and the lack of readily available assays for a large percentage of commonly used medicines, including prescription and over-the-counter drugs. Our toxicology screening program addresses the needs of both the Emergency Department Drug Screening and Drug of Abuse Screening. In Emergency Department Drug Screening, REMEDi HS is used as the general screening method. In Drug of Abuse Screening, the TDx is used for the initial screening of amphetamine-like substances and opiates, followed by REMEDi HS for the confirmation of positive samples. Emergency Department data collected at our institute over one year (September 1992 to August 1993) identified 57 different drugs in 713 samples. Opiates, narcotics and central stimulants accounted for 24% of the encountered drugs. Presently, there is no extensive reporting of misuse of benzodiazepines in this region. The detection of herbal ingredients like ephedrine and methylephedrine (from the Ma-Huang plant) in patient samples illustrates a large area often overlooked by western toxicology.
Asunto(s)
Control de Medicamentos y Narcóticos/métodos , Tamizaje Masivo/estadística & datos numéricos , Toxicología/métodos , Anfetamina/análisis , Anfetamina/envenenamiento , Humanos , Metanfetamina/análisis , Metanfetamina/envenenamiento , Narcóticos/análisis , Narcóticos/envenenamiento , Centros de Control de Intoxicaciones/estadística & datos numéricos , Trastornos Relacionados con Sustancias/clasificación , Taiwán , Salud UrbanaRESUMEN
The performance of a multi-wavelength UV detector for automated drug identification following liquid chromatographic separation was evaluated. The ability of selected wavelength ratios to distinguish two closely related drugs was considered at different concentrations. Calibration of the detector based on wavelength ratios was then utilized to standardize two different detectors and to evaluate instrument-to-instrument variation of a series of detectors. Reproducibility of the second-derivative zero intercept for these drug spectra was also evaluated. Standardization of detector performance by reference to these two parameters permitted the transfer of UV spectral libraries stored on one instrument to another without compromising the reliability of qualitative data.
Asunto(s)
Anfetaminas/orina , Cromatografía Liquida/métodos , Efedrina/orina , Rayos Ultravioleta , Calibración/normas , Cromatografía Liquida/instrumentación , Humanos , Fentermina/orina , Reproducibilidad de los ResultadosRESUMEN
This paper describes the application of an automated algorithm for drug identification following the liquid chromatographic on-line separation and purification of drugs in physiological fluids. Two hundred fifty-seven (257) drugs and 45 drug metabolites were assembled for testing. Two internal standards were used which monitored different columns in the multi-step analytical separation. Retention reproducibility over a nine month period was 4 p. cent or less for most drugs. The algorithm for matching unknown peaks against the stored library utilized relative retention, lambda maxima, normalized spectral overlays, wavelength ratios and zero-intercepts from the second derivative in a combined forward-reverse search. Most of the drugs which could not be unambiguously identified were sedatives which eluted in the first minutes of the chromatogram. Diasteromers were partially resolved. Repetitive analysis of 200-400 micrograms/l of amphetamine, diphenhydramine, imipramine and morphine were evaluated to establish an absorption cutoff of 12 mAbs, above which at least 95% of peaks were correctly identified. This corresponded to a signal-to-noise ratio of 12 for the scanning UV detector which was evaluated.
Asunto(s)
Cromatografía Liquida/métodos , Computación en Informática Médica , Preparaciones Farmacéuticas/análisis , Algoritmos , Humanos , Preparaciones Farmacéuticas/aislamiento & purificaciónRESUMEN
A major research goal of liposome pharmacology is the selective delivery of drugs to target cell populations while minimizing extraction by phagocytic macrophages and blood monocytes of the reticuloendothelial system. The liver is an ideal organ for studying targeting strategies using a variety of liposomes, inasmuch as its discontinuous capillaries have fenestrae through which liposomes less than 0.2 microns in diameter may escape into the extravascular space. In a previous kinetic study, we proposed that the hepatic uptake of small unilamellar vesicles (SUV) in mice was compatible with a model of uptake involving dual, parallel pathways. One is a saturable, phagocytic pathway of uptake mediated by Kupffer cells, the other is a nonsaturable, pinocytotic pathway of uptake mediated by parenchymal cells, favoring the latter pathway at high liposomal dose (Beaumier et al., 1983). In the present study, we demonstrated by the techniques of liver cells fractionation that the uptake of either the bovine brain sphingomyelin/cholesterol (2:1; mole/mole) SUV or distearoyl phosphatidylcholine/cholesterol (2:1; mole/mole) SUV by hepatic parenchymal cells was enhanced markedly by increasing the amount of injected dose of SUV. As high as 85 to 90% of the total liver dose can be attributed to the uptake of SUV by the hepatic parenchymal cells alone, when the injected dose reaches at or above 7.5 to 10 micrograms of lipid per g b.wt. The dose effect on the uptake of liposomes by hepatocytes appears to be a general phenomenon of neutral SUV. Our data suggested that blockade by dose permits a feasible approach to target SUV to hepatic parenchymal cells.
Asunto(s)
Liposomas/metabolismo , Hígado/metabolismo , Animales , Colesterol/farmacocinética , Relación Dosis-Respuesta a Droga , Portadores de Fármacos , Inulina/farmacocinética , Ratones , Ácido Pentético/farmacocinética , Esfingomielinas/farmacocinéticaRESUMEN
Targeting liposomes to specific tissues or cells require the unequivocal determination of the uptake of liposomes at the cellular level. The present report describes the preparation of liposomes entrapping a high specific activity of 111In3+-bound inulin, and the potential applications of a multiple labeling technique for characterizing the extent of uptake of liposomes by tissues or different cells in a given tissue in vivo. The labeling method involves the application of the technique of acetylacetone-mediated, ionophoric loading of 111In3+ into liposomes entrapping an inulin derivative to which a strong chelating agent, diethylenetriamine-pentaacetic acid (DTPA), is bound. Subsequent ionophoric removal of the weakly bound 111In3+ by incubating the previously 111In3+-loaded liposomes with 10 mM nitrilotriacetic acid and 100 microM tropolone at room temperature for 20 min results in the preparation of liposomes entrapping 111In3+-DTPA-inulin. Our method of preparation yields net efficiencies of converting 63-78% of the externally added 111In3+ to liposome-entrapped 111In3+-DTPA-inulin.
Asunto(s)
Endocitosis , Indio , Inulina , Liposomas , 1,2-Dipalmitoilfosfatidilcolina , Fenómenos Químicos , Química , Colesterol , Esfingomielinas , TropolonaRESUMEN
The synthesis, binding of radioactive cations, liposomal encapsulation, and biodistribution of the oxidized-inulin reaction product with ethylenediamine and diethylenetriaminepentaacetic acid (4) are described. The four-step synthesis of the inulin derivative proceeded in a good overall yield of 72%. The complex of the inulin derivative with either 67Ga3+ or 111In3+ was stable in vivo and did not readily distribute into tissues, being excreted primarily in urine after intravenous administration to mice. The liposome-entrapped inulin derivative can be loaded with radioactive heavy metal cations by mobile ionophores in high radiochemical yields of 80-91%. Following the intravenous administration of the liposomal encapsulation of the indium-111-labeled inulin derivative, the entrapped compound had a biodistribution characteristic of liposomes and allowed an estimation of the extent of the intracellular uptake of liposomes. The ability of the inulin derivative to chelate many different types of metals will allow the use of this probe for studying subtle differences in tissue distribution resulting from different drug targeting or delivery protocols in the same animal by multiple labeling techniques. Moreover, the chelate-conjugated inulin permits studies of the applications of drug delivery systems in primates or human subjects by noninvasive techniques such as gamma-scintigraphic or nuclear magnetic resonance imaging methods.
Asunto(s)
Inulina/síntesis química , Ácido Pentético/síntesis química , Animales , Radioisótopos de Galio , Radioisótopos de Indio , Inyecciones Intravenosas , Inulina/administración & dosificación , Inulina/farmacocinética , Liposomas/administración & dosificación , Ratones , Ratones Endogámicos BALB C , Ácido Pentético/administración & dosificación , Ácido Pentético/farmacocinética , Distribución TisularRESUMEN
The distribution of liposomes within the intravascular space and the extent to which they escape into extravascular space strongly impact on the application of lipid vesicles as a carrier for pharmacologically active agents. The present study investigates how intact small unilamellar vesicles (SUV) may be taken up by different tissues after intravenous injection into mice, using various types of SUV with different entrapped markers, lipid composition, size, doses of liposomal lipids and stability in the blood. Our focus was specifically on sphingomyelin (or distearoyl phosphatidylcholine)/cholesterol (2:1, mol/mol) SUV, which are known to be stable in the blood circulation. Our results indicated that, in addition to the reticuloendothelial tissues, intact SUV were taken up in several other parts of the body, including intestine, skin, carcass and legs. It appears that the accumulation of SUV in the intestine and the skin increases with time post-injection. Furthermore, from the kinetic data, the process of uptake of SUV by the skin and intestine is compatible with a non-saturable pathway, which follows first-order kinetics. This suggests that the cells involved in the uptake of SUV in the intestine and skin are not phagocytic cells, which are normally saturable.