Effects of low doses of erythromycin on the C-13 Spirulina platensis gastric emptying breath test and electrogastrogram: A controlled study in healthy volunteers

OBJECTIVE: Electrogastrography and stable isotope gastric emptying breath t ests (GEBTs) are relatively simple, noninvasive tests of gastric motor func tion that may be useful in monitoring the effects of therapeutic interventi ons. It was our primary objective to examine the effects of low dose i.v. e rythromycin on the results of the C-13 Spirulina platensis GEBT and electro gastrography. We were also interested in evaluating the reproducibility of these tests. METHODS: In 10 healthy subjects (five female, ages 23-37 yr), we simultaneo usly performed the GEBT, using a prepackaged meal (340 kcal), and electroga strography on each of four different occasions separated by at least 1 wk. After performance of baseline studies, they were repeated in random order a fter the infusion of 50 mg of erythromycin (Er50), 100 mg erythromycin (Er1 00), and a placebo (sa line). Breath samples were obtained at baseline and at 75, 90, and 180 min after the meal and T-1/2 and T-lag calculated. Elect rogastrography recordings began 30 min before the test meal and continued f or 2 h after the meal. RESULTS: Baseline and placebo T-1/2 and T-lag were similar. Er50 resulted i n a modest acceleration of gastric emptying (T-1/2 Er50 vs baseline vs plac ebo = 104.0 vs 132.7 vs 125.5 min) and reduction in lag time (T-1/2 Er50 vs baseline vs placebo = 47.2 vs 61.5 vs 56.2 min). A similar decrease was se en in response to Er100. The baseline and placebo fasting and fed electroga strography parameters were similar. After infusion of Er100, the percentage of normal slow waves in the first postprandial hour decreased relative to baseline and placebo (percent normogastria Er100 vs baseline vs placebo = 6 4.1 +/- 7.5 vs 82.4 +/- 6.4 vs 79.7 +/- 5.5). This corresponded with an inc rease in percent tachygastria during the same period and an overall decreas e in the mean dominant frequency. Similar but less striking changes were se en after administration of Er50. Replicate GEBTs showed a high degree of re producibility both within and between individuals for T-1/2 and T-lag. In c ontrast, replicate electrogastrograms revealed moderate to high variability for ail parameters except the dominant frequency. CONCLUSION: The stable isotope GEBT utilizing C-13 S. platensis demonstrate s responsiveness to the prokinetic effects of low dose i.v. erythromycin an d good reproducibility.