Effect of Roux-en-Y gastric bypass on the bioavailability of metoprolol from immediate and controlled release tablets: a single oral dose study before and after surgery.

Objective: Roux-en-Y gastric bypass (RYGB) surgery induces major changes in the gastrointestinal tract that may alter the pharmacokinetics of orally administered drugs. Results from pharmacokinetic studies are sparse. This study aimed to investigate the effect of RYGB on the bioavailability of metoprolol from immediate release (IR) and controlled release (CR) tablets in female patient volunteers before and after surgery. Methods: An explorative, two-phase, single oral dose pharmacokinetic study of metoprolol in female patients undergoing RYGB was carried out. The dose was administered twice in each patient, 1 month before and 6 months after surgery. After intake of either 100 mg of metoprolol IR or CR tablet serum concentration-time profiles of metoprolol were determined. The endpoint was the ratio of AUCafter/AUCbefore of metoprolol. Results: Twelve patients were included in the study (metoprolol IR: 7; metoprolol CR: 5). After intake of a metoprolol IR tablet major intraindividual and interindividual differences for area under the serum concentration versus time curve (AUC) of metoprolol before and after surgery were observed (range ratio AUC0-10 hours after/AUC0-10 hours before: 0.74-1.98). For metoprolol CR tablets a significant reduction in bioavailability of metoprolol was observed after surgery (range ratio AUC0-24 hours after/AUC0-24 hours before: 0.43-0.77). Conclusion: RYGB may influence the bioavailability of metoprolol from an IR tablet. The magnitude of changes in bioavailability after RYGB requires close monitoring of patients using metoprolol IR tablets and dose adjustment if deemed necessary. RYGB clearly reduces the bioavailability of metoprolol from a CR tablet. After RYGB clinicians may consider to increase the dose according to clinical response.

Is glycogen storage disease 1a associated with atherosclerosis?

UNLABELLED: Deficiency of microsomal glucose-6-phosphatase in liver and kidney leads to glycogen storage disease type 1a (GSD 1a). Notwithstanding intensive dietary therapy, moderate to severe dyslipidaemia and microalbuminuria, both known atherosclerotic risk factors, remain present. Although more patients reach adult age, no information is still available about accelerated atherosclerosis. The aim of our study was to investigate whether GSD 1a was associated with premature atherosclerosis. In nine adolescent patients (mean age 22.7+/-3.4 years) and nine matched healthy control subjects, lipid profile, blood pressure, ankle-brachial indices, aortic distensibility and intima-media thickness (IMT) of the carotid and femoral arteries were determined. As expected, lipid profiles were significantly unfavourable in the patient group compared with the control group. No differences were found in blood pressure, ankle-brachial indices and aortic distensibility between both groups. IMT segments were comparable in both groups, with even thinner segments in the patient group. In different multivariate models, GSD 1a remained an independent predictor for a thinner IMT (R(2)=0.90; beta=-0.69; P=0.018). CONCLUSION: glycogen storage disease type 1a is not associated with premature atherosclerosis, despite the existence of longstanding dyslipidaemia and microalbuminuria.