Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Remogliflozin etabonate: a novel SGLT2 inhibitor for treatment of diabetes mellitus

INTRODUCTION

Inhibitors of sodium-glucose co-transporter type 2 (SGLT2) represent a new class of anti-hyperglycemic agents with a unique mechanism of action. These drugs lower blood glucose by increasing urinary glucose excretion. Remogliflozin etabonate (RE) is a prodrug of remogliflozin, an SGLT2 inhibitor under development.

AREAS COVERED

The following article reviews all of the clinical studies published regarding metabolism, drug interaction, safety and efficacy of RE in healthy subjects, patients with type 1 and type 2 diabetes.

EXPERT OPINION

Available data suggest low potential for RE to interact with other drugs affecting the P450 system. Compared with placebo, RE reduces hemoglobin A1c (HbA1c) levels by an average of 0.5 - 1.0% after 12 weeks of therapy in drug-naive patients with type 2 diabetes. Because of its relatively short half-life, RE may be slightly more effective when used twice daily than once daily. One preliminary study also showed that RE decreased plasma glucose levels in type 1 diabetes. Advantages of RE include modest weight loss of ∼ 2 kg, low risk of hypoglycemia, and a trend toward decrease in blood pressure. The commonest adverse effects of RE are genital mycotic infections, urinary tract infections, and dizziness. However, further studies are needed to establish its long-term safety and efficacy, and to determine whether it has specific advantages over currently approved SGLT2 inhibitors.

Remogliflozin etabonate : a novel SGLT2 inhibitor for treatment of diabetes mellitus

INTRODUCTION

Inhibitors of sodium-glucose co-transporter type 2 (SGLT2) represent a new class of anti-hyperglycemic agents with a unique mechanism of action. These drugs lower blood glucose by increasing urinary glucose excretion. Remogliflozin etabonate (RE) is a prodrug of remogliflozin, an SGLT2 inhibitor under development. Areas covered: The following article reviews all of the clinical studies published regarding metabolism, drug interaction, safety and efficacy of RE in healthy subjects, patients with type 1 and type 2 diabetes. Expert opinion: Available data suggest low potential for RE to interact with other drugs affecting the P450 system. Compared with placebo, RE reduces hemoglobin A1c (HbA1c) levels by an average of 0.5 - 1.0% after 12 weeks of therapy in drug-naive patients with type 2 diabetes. Because of its relatively short half-life, RE may be slightly more effective when used twice daily than once daily. One preliminary study also showed that RE decreased plasma glucose levels in type 1 diabetes. Advantages of RE include modest weight loss of ∼ 2 kg, low risk of hypoglycemia, and a trend toward decrease in blood pressure. The commonest adverse effects of RE are genital mycotic infections, urinary tract infections, and dizziness. However, further studies are needed to establish its long-term safety and efficacy, and to determine whether it has specific advantages over currently approved SGLT2 inhibitors.

Randomized trial showing efficacy and safety of twice-daily remogliflozin etabonate for the treatment of type 2 diabetes

We compared the efficacy of twice-daily doses of remogliflozin etabonate (RE) and once-daily pioglitazone with placebo for reduction in glycated haemoglobin (HbA1c) concentration. In this 12-week, double-blind, randomized, active- and placebo-controlled trial, 336 treatment-naïve subjects with type 2 diabetes and an HbA1c of 7.0-9.5% (53-80 mmol/mol) were randomized to RE (50, 100, 250, 500 or 1000 mg twice daily), matching placebo or 30 mg pioglitazone once daily. The primary endpoint was change in HbA1c from baseline. Other endpoints included changes in body weight, lipid levels, safety and tolerability. RE produced a decreasing dose response in HbA1c at week 12 (p < 0.001), with reductions in HbA1c versus placebo ranging from 0.64 to 1.07% (p < 0.001). Statistically significant reductions in body weight for RE compared with placebo were also observed. Twice-daily RE resulted in a dose-ordered improvement in glycaemic control and was generally well tolerated.

Randomized efficacy and safety trial of once-daily remogliflozin etabonate for the treatment of type 2 diabetes

The sodium-dependent glucose transporter 2 (SGLT2) inhibitor remogliflozin etabonate (RE) was evaluated in a 12-week, double-blind, randomized, placebo- and active-controlled, parallel-group study. A total of 252 newly diagnosed and drug-naïve people with type 2 diabetes and glycated haemoglobin (HbA1c) concentrations of 7.0-≤9.5% (53-80 mmol/mol) were recruited. Participants were randomized to RE (100, 250, 500 or 1000 mg once daily or 250 mg twice daily), placebo or 30 mg pioglitazone once daily. The primary endpoint was change in HbA1c concentration from baseline. Secondary endpoints included changes in fasting plasma glucose, body weight and lipid profiles, safety and tolerability. We observed a statistically significant trend in the RE dose-response relationship for change from baseline in HbA1c at week 12 (p < 0.047). RE was generally well tolerated and no effects on LDL cholesterol were observed.