Severe hypoglycemia following venlafaxine intoxication: a case report

Dose-related hypoglycemia in venlafaxine poisoning: a retrospective cohort study

CONTEXT

Several case reports describe hypoglycemia in the context of venlafaxine overdose, while investigations at therapeutic dose suggested a neutral effect on glucose homeostasis. Studies on hypoglycemia in venlafaxine intoxication are lacking.

METHODS

Single-center retrospective cohort study of non-diabetic patients presenting with a laboratory-confirmed antidepressant overdose to the department of clinical toxicology of a tertiary care hospital over a 12-year period. Our main goal was to investigate the association of hypoglycemia as the primary outcome with venlafaxine exposure using multiple logistic regression. Multi-drug exposures were included. We further aimed to describe the association of blood glucose (BG)/hypoglycemia with antidepressant dose, seizures and length of hospital stay.

RESULTS

525 antidepressant intoxications were included, 85 of which involved venlafaxine. Hypoglycemia occurred in 34.1% (29/85) of venlafaxine intoxications and in 10.7% (47/440) of non-venlafaxine antidepressant overdoses. Venlafaxine exposure was significantly associated with hypoglycemia (adjusted odds ratio (OR): 6.6, 95% confidence interval (CI): 3.5-12.6). Venlafaxine-associated hypoglycemia was mainly mild (BG: 51-70 mg/dL), in 75.8% of cases, to moderate (BG: 31-50 mg/dL), in 20.7%, with one case of severe hypoglycemia (BG: 30 mg/dL). BG was significantly inversely correlated with dose in the venlafaxine group (Spearman's correlation coefficient: -0.47, p = 0.002) but not in other commonly prescribed antidepressants. Regardless of venlafaxine exposure, hypoglycemia was associated with seizures (adjusted OR: 5.3, 95% CI: 2.6-10.6) and with a 2.7 day increase in hospital length of stay (95% CI: 1.3-4.2).

CONCLUSION

A dose-related, mild to moderate hypoglycemia occurred in over one-third of venlafaxine poisonings. In overdose of other antidepressants, hypoglycemia was seen less frequently and without significant dose-dependency. Regardless of venlafaxine exposure, hypoglycemia was associated with seizures and prolonged length of stay, although these factors are likely primarily determined by other toxicities. BG monitoring in venlafaxine overdose should be considered.

Evaluation of venlafaxine on glucose homeostasis and oxidative stress in diabetic mice

Depression occurs frequently with diabetes affecting the quality of life. All major classes of antidepressants have been shown to have a direct pharmacologic effect on metabolic function, which further worsens glycemic control. There were no reports on the effects of venlafaxine on glucose levels and oxidative stress in diabetic animals. The present study evaluated the effects of venlafaxine (8 and 16 mg/kg per d) on glucose homeostasis along with oxidative stress in brain in diabetic mice (streptozotocin (STZ), 40 mg/kg per d for 5 days). We observed that 21 days of administration of venlafaxine (8 and 16 mg/kg per d) in diabetic mice significantly enhanced swimming in normal and STZ-treated mice with a corresponding reduction in immobility. No significant difference in blood glucose levels was observed in diabetic and normal mice following venlafaxine treatment. Venlafaxine (16 mg/kg) reversed STZ-induced elevated thiobarbituric acid reactive substance (TBARS) levels and also restored the glutathione (GSH) levels in diabetic mice. Venlafaxine (8 and 16 mg/kg) per se does not produce any significant effect in normal animals. The results indicate a dose-dependent antidepressant action of venlafaxine in diabetes-induced depressive mice. Furthermore, the blood glucose levels were not significantly altered in normal and diabetic mice. In addition, venlafaxine exhibited a decrease in TBARS and elevation in GSH levels in mice brain. Venlafaxine drug treatment appears to be safer for depression associated with diabetes.

Glucose dysregulation associated with antidepressant agents: an analysis of 17 published case reports

AIM OF THE REVIEW

Although there are several case reports in literature linking use of antidepressants and disturbances in glucose control, it is difficult to identify risk factors for serious adverse drug events from individual case reports. The aim of this review is to provide a descriptive analysis of the demographic and clinical characteristics of published glucose dysregulation case reports following initiation of antidepressant agents.

METHODS

Published case reports of glucose dysregulation associated with antidepressants were accessed through PubMed (Medline), PsycINFO, and Web of Science (WOS) between January 1, 1970 and April 30, 2010. The following key words were used: antidepressant agents, glucose dysregulation, hypoglycemia, hyperglycemia, diabetes mellitus, and diabetic ketoacidosis. Case reports were excluded if glucose dysregulation occurred after a drug overdose/improper dosing or after the patient was prescribed drugs known to cause glucose disturbances in addition to antidepressant agents.

RESULTS

Out of the 17 cases reports reviewed, nine (53%) were of hyperglycemia while eight (47%) were of hypoglycemia. Hyperglycemia was reported following treatment with clomipramine, fluvoxamine, imipramine, mianserin, mirtazapine, paroxetine, and sertraline. Hypoglycemia was reported following treatment with doxepine, fluoxetine, imipramine, nefazodone, nortriptyline, maprotiline, and sertraline. Fourteen out of the seventeen patients were female (82%) while ten had a history of diabetes mellitus (59%). The average age of the patients was 53.9 (SD = 17.5) years (range: 24-84 years). The time to onset of glucose dysregulation ranged from 4 days to 5 months after initiation of antidepressant therapy. More than two-thirds (68%) of the cases (n = 11) reported glucose control disturbances within 1 month of therapy.

CONCLUSIONS

It is not clear from published case reports whether changes in glucose regulation, following antidepressant therapy initiation are due to antidepressants or changes in mood and lifestyle. Nonetheless, healthcare providers should be aware of the potential changes in glucose regulation especially in the first month of antidepressant therapy, and use appropriate clinical and laboratory monitoring to prevent serious adverse events in patients at risk.

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.