Effects of anatomical position on esophageal transit time:A biomagnetic diagnostic technique

AIM： To study the esophageal transit time （ETT） and compare its mean value among three anatomical inclinations of the body; and to analyze the correlation of ETT to body mass index （BMI）. METHODS： A biomagnetic technique was implemented to perform this study： （1） The transit time of a magnetic marker （MM） through the esophagus was measured using two fluxgate sensors placed over the chest of 14 healthy subjects; （2） the EIF was assessed in three anatomical positions （at upright, fowler, and supine positions; 90°, 45° and 0°, respectively）. RESULTS： ANOVA and Tuckey post-hoc tests demonstrated significant differences between E-IT mean of the different positions. The ETT means were 5.2 ± 1.1 s, 6.1 ± 1.5 s, and 23.6 ± 9.2 s for 90°, 45° and 0°, respectively. Pearson correlation results were r = -0.716 and P 〈 0.001 by subjects＇ anatomical position, and r = -0.024 and P 〉 0.05 according the subject＇s BMI. CONCLUSION： We demonstrated that using this biomagnetic technique, it is possible to measure the ETT and the effects of the anatomical position on the ETT.

Pharmacokinetics of aminophylline delivered to the small intestine and colon using remote controlled capsules

Background A patented remote controlled capsule （RCC） has recently been developed to provide noninvasive drug delivery to selected sites in the human gut that allows assessment of regional gastrointestinal （GI） drug absorption under a normal physiological environment. The objective of this study was to investigate the rate and extent of aminophylline absorption after site-specific delivery of the drug in the GI tract using RCC and a magnetic marker monitoring （MMM） technique. Methods This study was conducted in twelve healthy male subjects, in a three-treatment, randomized, crossover manner with a 7-day washout. Eligible subjects received a 150 mg aminophylline dose through an oral administration, or via a remote controlled capsule, delivered to the small bowel or ascending colon. MMM was employed to monitor the GI transit of the RCC, and the radio-frequency signal was used to activate capsules at target sites. Blood samples were obtained at regular intervals until 24 hours post dose/activation. Plasma theophylline concentrations were measured by a TDx~ System Analyzer. A comparison of the PK profile with the oral dosing route of aminophylline was performed after delivery to the small bowel and colon. Results The RCC was well tolerated in volunteers. The mean capsule activation time for the small bowel and ascending colon was 2.07 hours and 6.08 hours post dose. Aminophylline had similar absorption profiles from the small bowel compared with the stomach, with an area under the curve （AUCt） ratio of 92% vs. the stomach, but a lower absorption profile from the ascending colon, with an AUCt ratio of 47.2% vs. the stomach. Conclusions The proprietary of the RCC and MMM technique offer the opportunity to obtain data on the intestinal absorption of a drug in humans under noninvasive conditions. Aminophylline is rapidly and efficiently absorbed from the small bowel. While colonic absorption was limited by the poor water condition although effective absorption was observed from the ascending colon. This provides an opportunity for rational development of modified-release formulations as well as alternative dosage forms.