RESUMEN
The growing interest in combinatorial chemistry has led to a new source of compounds from which a large number of leads has emerged over recent years. Parallel synthesis, in particular, allows a quick production of a wide number of individual compounds. A rapid analytical control is needed to determine their quality. A strategy using automated, fast reversed-phase C18 high-performance liquid chromatography with diode-array detection (LC-DAD-MS) followed by atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) and NMR has been developed for their characterisation and purity control. Complementary NMR analyses are done on selected compounds to provide a better structural characterisation of the expected compounds and their potential side-products. Validated libraries are then registered in ISIS databases using automated procedures.
Asunto(s)
Química Farmacéutica/métodos , Cromatografía Líquida de Alta Presión/métodos , Espectroscopía de Resonancia Magnética/métodos , Espectrometría de Masas/métodos , Control de CalidadRESUMEN
MDL 74,721 (I), sumatriptan(II) and naratriptan(III) are new 5-HT1-like agonists that have potential as a novel treatment for migraine. Liquid chromatographic-electrospray-mass spectrometric (LC-ESI-MS) assay have been developed to compare the pharmacokinetics of these three antimigraine compounds. The concentration of each parent drug was determined using a solid-phase extraction method and LC-ESI-MS analysis demonstrating the high sensitivity and specificity of the methods down to subnanogram levels in rabbit plasma samples. Pharmacokinetic parameters evaluated after administration of single intravenous and oral doses were very similar and the ANOVA analysis did not show any statistically significant differences for t1/2, Cmax, V or AUC (normalised). The pharmacokinetic parameters showed short t1/2 (range 1.14-1.9 h) either after intravenous (i.v.) or oral (p.o.) administration and high total body clearance (CL) after the p.o. dose both probably due to extensive and rapid metabolism of the parent drugs as suggested by the low values for bioavailability (range 13.4-22.8%).
Asunto(s)
Agonistas de Receptores de Serotonina/sangre , Agonistas de Receptores de Serotonina/farmacocinética , Vasoconstrictores/sangre , Vasoconstrictores/farmacocinética , Administración Oral , Animales , Cromatografía Liquida , Indoles/administración & dosificación , Indoles/sangre , Indoles/farmacocinética , Inyecciones Intravenosas , Masculino , Espectrometría de Masas , Piperidinas/administración & dosificación , Piperidinas/sangre , Piperidinas/farmacocinética , Conejos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Agonistas de Receptores de Serotonina/administración & dosificación , Sulfonamidas/administración & dosificación , Sulfonamidas/sangre , Sulfonamidas/farmacocinética , Sumatriptán/administración & dosificación , Sumatriptán/sangre , Sumatriptán/farmacocinética , Tetrahidronaftalenos/administración & dosificación , Tetrahidronaftalenos/sangre , Tetrahidronaftalenos/farmacocinética , Triptaminas , Vasoconstrictores/administración & dosificaciónRESUMEN
MDL 73,745 (2,2,2-trifluoro-1-(3-trimethylsilylphenyl) ethanone, CAS 132236(18-1) is a novel tight-binding inhibitor of acetylcholinesterase (AChE), which is in development as a potential therapeutic compound in the symptomatic treatment of Alzheimer's disease. Pharmacokinetics and pharmacodynamics of the compound were studied in the dog after single intravenous (i.v. 2 mg/kg), oral p.o. 10 mg/kg) and sub-cutaneous (s.c., 10 mg/kg) administrations of [14C]-MDL 73,745. Plasma concentrations of total radioactivity were much higher than those of parent drug after i.v., p.o. and s.c. administration, indicating extensive metabolism of the compound, although this was less after, s.c. administration than after p.o. administration. The bioavailability (F) was 34% after s.c. administration, compared with 4% after p.o. administration. The low bioavailability after p.o. administration was not due to poor drug absorption, as over 64% of the dose was absorbed. Pharmacokinetic parameters, calculated after i.v. administration, showed a terminal elimination half-life of 24 h, total body plasma clearance of around 70 ml/min/kg and apparent volume of distribution of 150 l/kg. AChE activity was almost 100% inhibited after i.v. administration, and over 80% inhibited 1 h after p.o. administration. In both cases, AChE activity returned to baseline levels by 12 h. AChE was around 80% inhibited 4 h after s.c. administration, and did not return to baseline levels until 36 h after drug administration. A combined pharmacokinetic-pharmacodynamic (PK-PD) effect model demonstrated that the extent of AChE inhibition could be correlated with plasma levels of the parent compound. As s.c. administration increased F, and led to longer AChE inhibition, transdermal (t.d.) delivery was assessed in the same animals. Patches, corresponding to a dose of 50 mg/kg, were applied to the shaved lateral abdominal skin for a period of 96 h. Sustained plasma concentrations of the parent drug were observed over the 96 h period of t.d. application. Mean (+/- SD) maximum plasma concentrations (Cmax) of 26.9 +/- 4.3 ng/ml were found 3.7 +/- 2.5 h after t.d. patch application und F was around 13%. AChE inhibition reached a maximum of 72% at 6 h after t.d. application and was still 35% at 96 h. The rate of release from the delivery system, per unit surface area, (ko) was calculated to be 7.7 micrograms/cm2. Transdermal delivery of MDL 73,745 thus decreased the important hepatic first-pass effect, and led to sustained plasma concentrations of drug, thus avoiding peaks and troughs which could lead to side-effects or poor efficacy.
Asunto(s)
Acetofenonas/farmacología , Acetofenonas/farmacocinética , Inhibidores de la Colinesterasa/farmacología , Inhibidores de la Colinesterasa/farmacocinética , Compuestos de Trimetilsililo/farmacología , Compuestos de Trimetilsililo/farmacocinética , Acetofenonas/administración & dosificación , Acetilcolinesterasa/sangre , Administración Cutánea , Administración Oral , Animales , Disponibilidad Biológica , Inhibidores de la Colinesterasa/administración & dosificación , Perros , Heces/química , Semivida , Inyecciones Intravenosas , Inyecciones Subcutáneas , Masculino , Compuestos de Trimetilsililo/administración & dosificaciónRESUMEN
An isocratic reversed-phase high-performance liquid chromatographic (HPLC) method using an Ultrasphere IP column has been developed for the determination of testosterone and its metabolites after incubation of 4-14C-labelled or unlabelled testosterone with rat liver microsomes. Compounds were eluted with methanol-water-tetrahydrofuran (35:55:10, v/v, pH 4.0) and detected by ultraviolet (UV) absorption at 245 nm. UV or on-line radioactivity detection can be used although, due to differences in detector cell volumes, peak resolution is slightly better with UV detection. Selectivity was validated by collecting HPLC peaks and verifying their identity by gas chromatography-mass spectrometry after derivatization by N,O-bis(trimethylsilyl)trifluoroacetamide-trimethylchlorosilane. A three-day validation was performed to determine the linearity, repeatability, reproducibility and accuracy of the method, using corticosterone as internal standard. The method is applicable to the measurement of cytochrome P-450 isoenzyme activities in rat liver.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Microsomas Hepáticos/metabolismo , Testosterona/aislamiento & purificación , Testosterona/metabolismo , Animales , Cromatografía Líquida de Alta Presión/estadística & datos numéricos , Cromatografía de Gases y Espectrometría de Masas , Masculino , Ratas , Ratas Sprague-Dawley , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
The effects of monoamine oxidase B (MAO-B) inhibition by mofegiline on the pharmacokinetics of p-tyramine and its major metabolite, p-hydroxyphenylacetic acid, were investigated in 24 healthy male volunteers. p-Tyramine doses were administered before and after a 14-day treatment period of 1, 12, or 24 mg mofegiline or placebo. Normalized p-tyramine for area under the plasma concentration-time curve after treatment were not significantly different from their respective before-treatment values for any of the dose groups. The relative bioavailability of p-tyramine after treatment was not significantly different from before treatment, although a tendency to a greater bioavailability was seen with the 12 and 24 mg doses. There were no significant differences between pharmacokinetic parameters for p-hydroxyphenylacetic acid. The data suggest that mofegiline maintains its selectivity for MAO-B in the intestine and liver at doses up to and including 24 mg. Therefore these doses would not be expected to be associated with the hypertensive crises normally associated with the "cheese effect."
Asunto(s)
Compuestos Alílicos/farmacología , Butilaminas/farmacología , Inhibidores de la Monoaminooxidasa/farmacología , Fenilacetatos/farmacocinética , Tiramina/farmacocinética , Adulto , Disponibilidad Biológica , Método Doble Ciego , Humanos , Masculino , Fenilacetatos/sangre , Tiramina/sangre , Tiramina/metabolismoRESUMEN
Mofegiline or MDL 72,974A ((E)-4-fluoro-beta-fluoromethylene benzene butanamine hydrochloride) is a selective enzyme-activated irreversible inhibitor of monoamine oxidase B, which is under development for use in the treatment of Parkinson's disease. Male beagle dogs were given single p.o. (20 mg/kg) and i.v. (5 mg/kg) doses of [14C]-Mofegiline. Total radioactivity excreted in urine and feces over 96 hr was, respectively, 75.5 +/- 3.8 and 6.3 +/- 3.4% of the dose after p.o. and 67.9 +/- 0.5 and 3.9 +/- 2.4% after i.v. administration. Unchanged drug in urine represented 3% of the dose after po and less than 1% after i.v. administration. Mofegiline was thus extensively metabolized in dogs, and urinary excretion was the major route of elimination of metabolites. HPLC, with on-line radioactivity detection, showed the presence of four major peaks (M1, M2, M3, and M4), representing respectively 50, 9, 5, and 0.5% of the administered dose excreted in 0-24 hr urine. TSP-LC-MS, FAB-MS, and NMR spectra of the purified metabolites were obtained. M1, the major metabolite in dogs, was shown to have undergone defluorination of the beta-fluoromethylene moiety, and one carbon addition. Its structure was confirmed to be a cyclic carbamate. M2 was a N-carbamoyl O-beta-D-glucuronide conjugate of parent drug. The formation of M1 and M2 is likely to involve initial reversible addition of CO2 to the primary amine function. M3 was a N-succinyl conjugate of the parent drug. M4 had also undergone defluorination to yield a urea adduct of an unsaturated alpha, beta aldehyde. Structures of M1 and M3 were further confirmed by comparing their MS and NMR spectra with those of authentic reference compounds. TSP-LC-MS ion chromatograms of human urine, obtained from two male volunteers after p.o. administration of 24 mg of drug, showed selected molecular ion peaks with the same retention time as the metabolites identified in dogs. In humans, these common metabolites represented a similar percentage of the administered dose to that in dogs. The present study demonstrates that NMR, TSP-LC-MS are complementary analytical techniques, which allow structural identification of unhydrolyzed drug conjugates. The formation of carbamates of amine-containing drugs may be more common than previously reported.
Asunto(s)
Compuestos Alílicos/farmacocinética , Butilaminas/farmacocinética , Carbamatos/metabolismo , Inhibidores de la Monoaminooxidasa/farmacocinética , Administración Oral , Compuestos Alílicos/administración & dosificación , Compuestos Alílicos/orina , Animales , Biotransformación , Butilaminas/administración & dosificación , Butilaminas/orina , Cromatografía Liquida , Perros , Humanos , Inyecciones Intravenosas , Espectroscopía de Resonancia Magnética , Masculino , Espectrometría de Masas , Metilación , Inhibidores de la Monoaminooxidasa/administración & dosificación , Inhibidores de la Monoaminooxidasa/orina , Espectrometría de Masa Bombardeada por Átomos Veloces , Distribución TisularRESUMEN
A highly sensitive and specific assay has been developed for the determination of MDL 73745 [2,2,2-trifluoro-1-(3-trimethylsilyl-phenyl) ethanone] (I) and the internal standard (MDL 74398) at the nanomolar level in dog plasma and urine by gas chromatography/mass spectrometry. After a single-step extraction process, an aliquot was directly injected onto the gas chromatograph column. The mass spectrometer was run in the negative ion chemical ionization mode with ammonia as reagent gas, and was set to monitor the abundant M-. ion at m/z 246 of both compounds. The method yielded a linear response over the concentration range 0.1-10 pmol 100 microliters -1 plasma or urine. Within-day reproducibility at a concentration of 0.25, 1 and 5 pmol 100 microliters -1 plasma was 8.6%, 1.0% and 1.0%, respectively. The method was applied to the determination of I in plasma and urine after administration of 1 mg kg-1 i.v. and 10 mg kg-1 p.o. to dogs.
Asunto(s)
Acetofenonas/análisis , Inhibidores de la Colinesterasa/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Compuestos de Trimetilsililo/análisis , Acetofenonas/sangre , Acetofenonas/orina , Animales , Inhibidores de la Colinesterasa/sangre , Inhibidores de la Colinesterasa/orina , Perros , Masculino , Compuestos de Trimetilsililo/sangre , Compuestos de Trimetilsililo/orinaRESUMEN
MDL 72974A ((E)-4-fluoro-beta-fluoromethylene benzene butanamine HCl salt, CAS 120635-25-8) is a new irreversible inhibitor of the B form of monoamine oxidase (MAO-B). MDL 72974A's pharmacokinetic parameters were evaluated after administration of a single oral dose and after multiple oral doses. The concentration of parent drug was determined in plasma using a solid-liquid extraction method and gas chromatographic-mass spectrometric analysis. MDL 72974A produced significant inhibition of platelet MAO-B activity at all of the doses > or = 0.5 mg (> 95% after 1 h). The pharmacokinetic parameters showed a short plasma half-life (1 h) and a high total body clearance (Cltot) both probably due to extensive and rapid metabolism as suggested by the low urinary excretion of unchanged drug (< 1% of the administered dose). After the administration of multiple doses of MDL 72974A, a decrease in Cltot and a concomitant increase in the AUC and t1/2, was observed, probably due to a change in the elimination rate of MDL 72974A. Due to the once-a-day dosing schedule and the short plasma t1/2, no drug accumulation occurred.
Asunto(s)
Compuestos Alílicos , Butilaminas/farmacocinética , Inhibidores de la Monoaminooxidasa/farmacocinética , Monoaminooxidasa/metabolismo , Plaquetas/enzimología , Método Doble Ciego , Cromatografía de Gases y Espectrometría de Masas , Semivida , Humanos , Indicadores y ReactivosRESUMEN
A sensitive and specific assay has been developed for the quantitative measurement in human plasma and urine of the irreversible inhibitor of monoamine oxidase B [(E)-4-fluoro-beta-fluoromethylenebenzene-butanamine HCl salt] (MDL 72974A) (I). This assay is based on gas chromatography-mass spectrometry with ammonia as the chemical ionization reagent gas. After addition of 1-fluoro-2-(4-chlorobenzene)-ethanamine HCl salt (MDL 71946A) as the internal standard, plasma (1 ml) and urine (100 microliter) samples were extracted using an automated solid-liquid extraction procedure on CN columns. The eluent was dried with a stream of nitrogen, and the residue was derivatized with pentafluoropropionic anhydride. Selected-ion monitoring of the [MNH4]+ ions m/z 361 (I) and 351 (internal standard) was used for quantification. The method yielded a linear response over the concentration range 0.25-100 pmol/ml in plasma with a limit of quantitation of 0.25 pmol/ml. The within-day reproducibility at a concentration of 5 pmol/ml was 4.6% and at a concentration of 50 pmol/ml was 1.3%. The day-to-day reproducibility was 5.2 and 7.0% at concentrations of 10 and 30 pmol/ml, respectively. The method was applied to the quantification of I in plasma and urine after the administration of 12-mg doses of I to a healthy male volunteer.