Gastroesophageal Reflux and Microaspiration in Lung Transplant Recipients: The Utility of a Single Esophageal Manometry and pH Probe Monitoring Study

BACKGROUND

Gastroesophageal reflux (GER) in recipients of lung transplant (LTX) is associated with chronic allograft rejection, presumably via microaspiration that damages airway epithelium. Most LTX programs perform a single post-LTX esophageal study to evaluate for GER; the efficacy of this test is unclear.

METHODS

Patients with 1 year of post-LTX follow-up, including routine bronchoscopies with bronchoalveolar lavage fluid (BALF) samples as well as high-resolution esophageal manometry and pH probe monitoring (HREMpH), were evaluated. BALF samples were analyzed with competitive enzyme-linked immunosorbent assay to detect bile salts, which are indicative of aspiration. These results were compared to results of HREMpH studies post LTX.

RESULTS

Ninety BALF samples were analyzed for bile salts and acted as disease positive for this evaluation. Of the 13 HREMpH cases, 8 were positive for GER, but only 3 were positive for bile salts via assay. Of the 5 HREMpH-negative cases, 2 experienced aspiration. A solitary HREMpH study had 60.0% sensitivity and 37.5% specificity with positive and negative likelihood ratios: 0.96 and 1.07, respectively.

CONCLUSION

Microaspiration appears to be an intermittent phenomenon, and HREMpH screening poorly correlates with BALF evidence of aspiration; which may not be adequate. As aspiration detection is crucial in this population, further analysis is warranted.

Gastroparesis and functional dyspepsia: excerpts from the AGA/ANMS meeting

BACKGROUND

Despite the relatively high prevalence of gastroparesis and functional dyspepsia, the aetiology and pathophysiology of these disorders remain incompletely understood. Similarly, the diagnostic and treatment options for these two disorders are relatively limited despite recent advances in our understanding of both disorders.

PURPOSE

This manuscript reviews the advances in the understanding of the epidemiology, pathophysiology, diagnosis, and treatment of gastroparesis and functional dyspepsia as discussed at a recent conference sponsored by the American Gastroenterological Association (AGA) and the American Neurogastroenterology and Motility Society (ANMS). Particular focus is placed on discussing unmet needs and areas for future research.

Sequential group trial to determine gastrointestinal site of absorption and systemic exposure of azathioprine

Azathioprine (AZA) is used in the treatment of patients with refractory inflammatory bowel disease; however, its use is limited because of systemic toxicity associated with long-term use. Ileocecal delivery of AZA might be advantageous if local intestinal therapeutic effects could be provided with decreased systemic side effects. Decreased cecal systemic absorption would allow higher dosages of AZA to be administered. A two-phase study was performed to compare the systemic exposure of AZA and 6-mercaptopurine (6-MP) following administration of AZA into the stomach, jejunum, and cecum and to compare the systemic exposure to AZA and 6-MP following administration of three different dosages of AZA into the cecum. In phase I, six healthy male volunteers received three 50 mg sequential doses of AZA via an oral tube directly placed into the stomach, jejunum, and cecum, respectively. In phase II, six healthy male volunteers received three different dosages (50, 300, 600 mg of AZA) into the cecum. Plasma concentrations of AZA and 6-MP at various times were quantified and area under the plasma concentration-time curve (AUC) and mean residence time (MRT) were determined. No significant differences in the AUC of AZA were seen at the different sites. The AUC of 6-MP following administration of AZA into the jejunum (67.0 +/- 30.1 ng x hr/ml) was higher compared to the stomach (39.9 +/- 38.1 ng/hr/ml) and cecum (29.2 +/- 10.9 ng x hr/ml). Jejunal absorption was 68% higher than absorption from the stomach and 129% higher than that of the cecum. Gastric absorption was 27% higher than that of the cecum. Increased dosages given into the cecum resulted in increased AUCs of AZA and 6-MP. The AUCs of AZA following 50, 300, and 600 mg dosages were 16.9 +/- 7.4, 52.3 +/- 67.2, and 132 +/- 151 ng x hr/ml, respectively, and the AUCs of 6-MP were 22.2 +/- 14.9, 63.4 +/- 50.6, and 104 +/- 115 ng x hr/ml, respectively. Systemic exposure to 6-MP is reduced following administration of AZA into the cecum, most likely secondary to reduced absorption of 6-MP from the colon. Higher dosages of AZA presented to the cecum do result in increased systemic absorption, but may still allow more drug to be administered with less toxicity than the same dose received orally.

A double-blind multicenter comparison of domperidone and metoclopramide in the treatment of diabetic patients with symptoms of gastroparesis

OBJECTIVE

A double-blind, multicenter, randomized trial was conducted to compare the side effects and efficacy of domperidone and metoclopramide in symptomatic diabetic gastroparesis.

METHODS

Ninety-three insulin-dependent diabetes patients with a > or = 3-month history of gastroparesis symptoms were recruited; 48 received domperidone 2 x 10-mg tablets 4 times daily, and 45 received metoclopramide 1 x 10-mg tablet + 1 placebo tablet 4 times daily. Nausea, vomiting, bloating/distension, and early satiety were evaluated for severity after 2 and 4 wk. Adverse central nervous system (CNS) effects of somnolence, akathisia, asthenia, anxiety, depression, and reduced mental acuity were elicited and graded for severity at 2 and 4 wk.

RESULTS

Domperidone and metoclopramide were equally effective in alleviating symptoms of diabetic gastroparesis. Elicited adverse CNS effects were more severe and more common with metoclopramide. Somnolence was acknowledged by 49% of patients (mean severity score, 1.03) after 4 wk of metoclopramide compared with 29% of patients (mean severity score, 0.49) after 4 wk of domperidone (incidence, p = 0.02; severity; p = 0.03). A reduction in mental acuity was acknowledged by 33% of patients (mean severity score, 0.62) after 4 wk of metoclopramide, compared with 20% of patients (mean severity score, 0.27) after 4 wk of domperidone (incidence, p = 0.04; severity, p = 0.04). Akathisia, asthenia, anxiety, and depression were also acknowledged less often, and at a lower severity, after 4 wk of domperidone, although these differences were not statistically significant.

CONCLUSIONS

Domperidone and metoclopramide effectively reduce the symptoms of diabetic gastroparesis; CNS side effects are more pronounced with metoclopramide.

A double-blind multicenter comparison of domperidone and metoclopramide in the treatment of diabetic patients with symptoms of gastroparesis

OBJECTIVE

A double-blind, multicenter, randomized trial was conducted to compare the side effects and efficacy of domperidone and metoclopramide in symptomatic diabetic gastroparesis.

METHODS

Ninety-three insulin-dependent diabetes patients with a > or = 3-month history of gastroparesis symptoms were recruited; 48 received domperidone 2 x 10-mg tablets 4 times daily, and 45 received metoclopramide 1 x 10-mg tablet + 1 placebo tablet 4 times daily. Nausea, vomiting, bloating/distension, and early satiety were evaluated for severity after 2 and 4 wk. Adverse central nervous system (CNS) effects of somnolence, akathisia, asthenia, anxiety, depression, and reduced mental acuity were elicited and graded for severity at 2 and 4 wk.

RESULTS

Domperidone and metoclopramide were equally effective in alleviating symptoms of diabetic gastroparesis. Elicited adverse CNS effects were more severe and more common with metoclopramide. Somnolence was acknowledged by 49% of patients (mean severity score, 1.03) after 4 wk of metoclopramide compared with 29% of patients (mean severity score, 0.49) after 4 wk of domperidone (incidence, p = 0.02; severity; p = 0.03). A reduction in mental acuity was acknowledged by 33% of patients (mean severity score, 0.62) after 4 wk of metoclopramide, compared with 20% of patients (mean severity score, 0.27) after 4 wk of domperidone (incidence, p = 0.04; severity, p = 0.04). Akathisia, asthenia, anxiety, and depression were also acknowledged less often, and at a lower severity, after 4 wk of domperidone, although these differences were not statistically significant.

CONCLUSIONS

Domperidone and metoclopramide effectively reduce the symptoms of diabetic gastroparesis; CNS side effects are more pronounced with metoclopramide.

Case report: interaction of rifampin and nortriptyline

Rifampin is well documented to cause numerous clinically significant drug interactions because of its induction of the hepatic cytochrome P450 system. The metabolism of nortriptyline and other tricyclic antidepressants is induced and inhibited by this enzyme system. To the authors' knowledge, this is only the second case report in the literature regarding a possible interaction between rifampin and a tricyclic antidepressant. Nortriptyline serum concentrations were not detectable while rifampin was given concurrently. Two weeks after discontinuation of rifampin, nortriptyline concentrations increased dramatically. Further study of this possible interaction is warranted.

Improvement in autonomic and gastric function following pancreas-kidney versus kidney-alone transplantation and the correlation with quality of life

We conducted a series of studies to document changes in autonomic and gastrointestinal function following pancreas-kidney and kidney-alone transplantation, define how autonomic function is associated with quality of life, and identify how transplantation alters the quality of life of diabetic transplant recipients. Uremic type I diabetic patients receiving combined pancreas-kidney (n = 23) or kidney-alone (n = 16) transplants completed pre- and 12-month-posttransplant evaluation of vasomotor function (total capillary pulse amplitude, capillary vasoconstriction response to cold, capillary response to postural adjustments), cardiac function (R-R interval variation, valsalva ratio), overall autonomic function (total autonomic score, autonomic index), gastric function (cutaneous electrogastrography, gastric emptying, total gastrointestinal symptoms score), and quality of life (sickness impact profile). Kidney recipients experienced nonsignificant improvement in autonomic function with significant improvement in total symptom score. In contrast, pancreas-kidney recipients demonstrated significant improvement in postural adjustment ratio (P < or = .0085), valsalva ratio (P < or = .0348), electrogastography (P < or = .0159), and total symptom score (P < or = .0001). Improvement or stabilization of gastric function occurred for 12 of 23 pancreas-kidney patients (52%) versus 5 of 12 kidney-alone patients (41.7%). A path analysis of 56 diabetic patients having a wide range in diabetic autonomic neuropathy, found the sickness impact profile to correlate with valsalva ratio (r = .36, P < or = .0056), R-R interval (r = .27, P < or = .0396), and vasoconstriction (r = .24, P < or = .064). Together, autonomic function measures accounted for 15.2% of the total variance in the sickness impact profile. Sickness impact profile scores also significantly improved for both groups of transplant recipients.