RESUMEN
The gastrointestinal tract is usually the preferred site of absorption for most therapeutic agents, as seen from the standpoints of convenience of administration, patient compliance and cost. In recent years there has been a tendency to employ sophisticated systems that enable controlled or timed release of a drug, thereby providing a better dosing pattern and greater convenience to the patient. Although much about the performance of a system can be learned from in vitro release studies using conventional and modified dissolution methods, evaluation in vivo is essential in product development. The non-invasive technique of gamma-scintigraphy has been used to follow the gastrointestinal transit and release characteristics of a variety of pharmaceutical dosage forms. Such studies provide an insight into the fate of the delivery system and its integrity and enable the relationship between in vivo performance and resultant pharmacokinetics to be examined (pharmacoscintigraphy).
Asunto(s)
Sistema Digestivo/diagnóstico por imagen , Sistema Digestivo/metabolismo , Preparaciones Farmacéuticas/administración & dosificación , Farmacocinética , Administración Oral , Animales , Formas de Dosificación , Humanos , CintigrafíaRESUMEN
The aim of the present study was to correlate the gastric emptying (GE) of nondisintegrating tablets with changes in gastrointestinal (GI) motility. Eight, healthy, male subjects each received 5 x 7-mm radiolabeled tablets, a radiolabeled meal, and a radiotelemetry capsule (RTC). Transit of the radiolabeled formulations was followed by gamma scintigraphy and the RTC detected contractile activity in the GI tract. The study demonstrated that 7-mm tablets can empty from the fed stomach, prior to the onset of interdigestive activity. Those tablets that were not emptied during fed activity were retained through the period of quiescence associated with the onset of the migrating myoelectric complex (MMC) and left the stomach during contractions associated with phase 2 and 3 activity. The RTC was retained in the stomach and was emptied only by large phase 3 contractions commonly termed the "housekeeper" wave. However, in one subject, the RTC was retained in the stomach for over 12 hr, during which time three distinct phase 3 complexes were monitored.
Asunto(s)
Vaciamiento Gástrico/fisiología , Motilidad Gastrointestinal/fisiología , Comprimidos , Adulto , Celulosa/análogos & derivados , Humanos , Radioisótopos de Indio , Masculino , Complejo Mioeléctrico Migratorio/fisiología , Cintigrafía , Estómago/diagnóstico por imagen , Estómago/fisiología , TelemetríaRESUMEN
The variability in the gastrointestinal transit of a multiple-unit and single-unit dosage form was investigated following a light breakfast in six, healthy, male volunteers after repeated weekly administration. The dosage forms were labeled with gamma-emitting radionuclides and the transit of the formulations was monitored on 4 separate study days using the technique of dual-isotope gamma scintigraphy. Gastric emptying times and small intestinal transit times were calculated and compared statistically within and between subjects using the standard deviation and coefficient of variance. The variability in gastric emptying of single- and multiple-unit systems was large; the intrasubject variation being less than the intersubject. There was less variation in small intestinal transit times for the single- and multiple-unit formulations than in gastric emptying, intrasubject variation again being less than intersubject variation.