Disopyramide-induced hypoglycemia: case report and review of the literature

Drug-induced hyperinsulinemic hypoglycemia: An update on pathophysiology and treatment

The initial step for the differential diagnosis of hypoglycemia is to determine whether it is hyperinsulinemic or non hyperinsulinemic. Existing literature discusses drug-related hypoglycemia, but it misses a focus on drug-induced hyperinsulinemic hypoglycemia (DHH). Here we reviewed the association existing between drugs and hyperinsulinemic hypoglycemia. We primarily selected on the main electronic databases (MEDLINE, EMBASE, Web of Science, and SCOPUS) the reviews on drug-induced hypoglycemia. Among the drugs listed in the reviews, we selected the ones linked to an increase in insulin secretion. For the drugs missing a clear association with insulin secretion, we investigated the putative mechanism underlying hypoglycemia referring to the original papers. Our review provides a list of the most common agents associated with hyperinsulinemic hypoglycemia (HH), in order to facilitate both the recognition and the prevention of DHH. We also collected data about the responsiveness of DHH to diazoxide or octreotide.

Drug-induced hypoglycaemia: an update

Drugs are the most frequent cause of hypoglycaemia in adults. Although hypoglycaemia is a well known adverse effect of antidiabetic agents, it may occasionally develop in the course of treatment with drugs used in everyday clinical practice, including NSAIDs, analgesics, antibacterials, antimalarials, antiarrhythmics, antidepressants and other miscellaneous agents. They induce hypoglycaemia by stimulating insulin release, reducing insulin clearance or interfering with glucose metabolism. Several drugs may also potentiate the hypoglycaemic effect of antidiabetic agents. Administration of these agents to individuals with diabetes mellitus is of most concern. Many of these drugs, and depending on clinical setting, may also induce hyperglycaemia. Drug-induced hepatotoxicity and nephrotoxicity may lead in certain circumstances to hypoglycaemia. Some drugs may also induce hypoglycaemia by causing pancreatitis. Drug-induced hypoglycaemia is usually mild but may be severe. Effective clinical management can be handled through awareness of this drug-induced adverse effect on blood glucose levels. Herein, we review pertinent clinical information on the incidence of drug-induced hypoglycaemia and discuss the underlying pathophysiological mechanisms, and prevention and management.

Mechanism of disopyramide-induced hypoglycaemia in a patient with Type 2 diabetes

BACKGROUND

Disopyramide, an antiarrhythmia drug, has been reported to cause hypoglycaemia. Pre-existing factors that increase the concentration of the drug in the blood increase the risk of hypoglycaemia. Furthermore, other factors can also increase the risk of hypoglycaemia even when disopyramide levels are in the therapeutic range. It has been proposed that disopyramide-induced hypoglycaemia is caused by inhibition of the pancreatic B-cell K(ATP) channels.

CASE REPORT

We report a case of severe disopyramide-induced hypoglycaemia in a 62-year-old woman with Type 2 diabetes taking low-dose glimepiride treatment. She had not experienced hypoglycaemia prior to the start of disopyramide therapy. No further hypoglycaemic episodes occurred following withdrawal of disopyramide therapy. FUNCTIONAL STUDY: Current recordings of K(ATP) channels expressed in Xenopus oocytes showed that at their estimated therapeutic concentrations, disopyramide and glimepiride inhibited K(ATP) channels by about 50-60%. However, when both drugs were applied together, K(ATP) channels were almost completely closed (approximately 95%). Such dramatic inhibition of K(ATP) channels is sufficient to cause B-cell membrane depolarization and stimulate insulin secretion.

CONCLUSIONS

Disopyramide therapy is not recommended for patients treated with K(ATP) channel inhibitors.

Drug-Induced Endocrine and Metabolic Disorders

Complex interactions exist amongst the various components of the neuroendocrine system in order to maintain homeostasis, energy balance and reproductive function. These components include the hypothalamus-pituitary- adrenal and -gonadal axes, the renin-angiotensin-aldosterone system, the sympathetic nervous system and the pancreatic islets. These hormones, peptides and neurotransmitters act in concert to regulate the functions of many organs, notably the liver, muscles, kidneys, thyroid, bone, adrenal glands, adipocytes, vasculature, intestinal tract and gonads, through many intermediary pathways. Endocrine and metabolic disorders can arise from imbalance amongst numerous hormonal factors. These disturbances may be due to endogenous processes, such as increased secretion of hormones from a tumour, as well as exogenous drug administration. Drugs can cause endocrine abnormalities via different mechanisms, including direct alteration of hormone production, changes in the regulation of the hormonal axis, effects on hormonal transport, binding, and signalling, as well as similar changes to counter-regulatory hormone systems. Furthermore, drugs can affect the evaluation of endocrine parameters by causing interference with diagnostic tests. Common drug-induced endocrine and metabolic disorders include disorders of carbohydrate metabolism, electrolyte and calcium abnormalities, as well as drug-induced thyroid and gonadal disorders. An understanding of the proposed mechanisms of these drug effects and their evaluation and differential diagnosis may allow for more critical interpretation of the clinical observations associated with such disorders, better prediction of drug-induced adverse effects and better choices of and rationales for treatment.

Drug-induced hypoglycemia

Therapeutically administered antidiabetic drugs, notably insulin and the sulfonylureas, are undoubtedly the most common cause of hypoglycemia encountered in clinical practice. Nevertheless, an impressive list of other drugs can produce hypoglycemia unpredictably in seemingly healthy individuals in whom it may masquerade as spontaneous hypoglycemia. Unless the true cause is identified when the patient is first seen, fruitless and expensive overinvestigation may ensue. The most important drugs are discussed herein and brief mention made of those for which coincidence has not been eliminated.

Hypoglycemia induced by interaction between clarithromycin and disopyramide

A 59-year-old man receiving hemodialysis was hospitalized due to severe hypoglycemic attack. The patient had been treated with disopyramide (50 mg/day) because of paroxysmal atrial fibrillation. Hypoglycemia occurred after taking clarithromycin (CAM, 600 mg/day), a macrolide antibiotic. The serum disopyramide concentration reached 8.0 micrograms/ml (23.6 microM) in the presence of CAM, while it was 1.5 micrograms/ml before the addition of CAM. A 75 g oral glucose tolerance test and daily profiles of blood glucose value showed that blood glucose levels were significantly lower in the presence of CAM and disopyramide compared to that in the absence of these drugs. The Turner index in the presence of CAM and disopyramide was significantly higher than that in the absence of these drugs, suggesting that a toxic concentration of disopyramide enhanced insulin secretion, resulting in the induction of hypoglycemic attacks, in which the inhibitory effects of CAM on the hepatic chytochrome P-450 might be involved. QT and QTc intervals were prolonged in the presence of CAM and disopyramide, but torsades de points were not observed in this patient receiving nicorandil (15 mg/day). Thus, it should be taken into account that life-threatening hypoglycemia may result from the interaction between clarithromycin and disopyramide.

Poisoning by sodium channel blocking agents

Poisoning by drugs that block voltage-gated sodium channels produces intraventricular conduction defects, myocardial depression, bradycardia, and ventricular arrhythmias. Human and animal reports suggest that hypertonic sodium bicarbonate may be effective therapy for numerous agents possessing sodium channel blocking properties, including cocaine, quinidine, procainamide, flecainide, mexiletine, bupivacaine, and others.

Disopyramide blocks pancreatic ATP-sensitive K+ channels and enhances insulin release

An antiarrhythmic agent, disopyramide, was found to enhance the insulin secretory capacity of Wistar rat pancreatic islets with a half-maximal concentration of 23.3 microM. Employing a patch-clamp technique, disopyramide was found to inhibit ATP-sensitive K+ (KATP) channel activity in rat pancreatic beta-cells in primary culture without altering the unitary conductance. Half-maximal inhibition was achieved by the addition of 3.6 microM disopyramide to the intracellular bathing solution in the inside-out mode, 11.0 microM to the extracellular bathing solution in the outside-out mode, and 87.4 microM in the cell-attached mode. The binding of [3H]glibenclamide to pancreatic islets was inhibited by unlabeled glibenclamide but not by unlabeled disopyramide. Based on these observations, it is concluded that disopyramide blocks pancreatic KATP channels via binding to a site(s) distinct from the sulfonylurea receptor. This effect may be causatively involved in disopyramide-induced hypoglycemia.

Inadequate adrenergic response to disopyramide-induced hypoglycemia

OBJECTIVE

To report a case of disopyramide-induced hypoglycemia and to discuss the observed inadequate adrenergic response in this patient. Risk factors, possible etiologies, and preventive measures are also discussed.

DATA SOURCES

References from case reports and review articles as identified by MEDLINE.

DATA SYNTHESIS

A wide variety of drugs has been implicated as causing hypoglycemia. The mechanism for drug-induced hypoglycemia is known for the majority of these agents. Case reports of disopyramide-induced hypoglycemia have been reported in the literature, but the mechanism of action is unclear. We report a case of disopyramide-induced hypoglycemia in which counter-regulatory hormones, serum insulin, and C-peptide concentrations were obtained. From these data, it appears that disopyramide-induced hypoglycemia results from endogenous insulin secretion, with concomitant inadequate counterregulatory response.

CONCLUSIONS

Although a rare occurrence, disopyramide-induced hypoglycemia is potentially life-threatening. Patients at risk for this reaction need to be identified prior to the institution of disopyramide therapy. Patients at risk for hypoglycemia should be monitored while on disopyramide and disopyramide blood concentrations should be maintained at the lower end of the therapeutic range, or alternative agents should be considered.