Type B Lactic Acidosis Associated With Venlafaxine Overdose

Area of Science:

• Toxicology
• Internal Medicine
• Pharmacology

Background:

• Type B lactic acidosis is rare and potentially fatal, often linked to medications like metformin.
• Known causes include metformin, linezolid, and nucleoside reverse-transcriptase inhibitors in HIV patients.

Purpose of the Study:

• To report the first case of type B lactic acidosis induced by venlafaxine overdose.
• To highlight venlafaxine as a potential cause of non-hypoperfusion/hypoxemia-related lactic acidosis.

Main Methods:

• A case study of a 55-year-old male with intentional overdose of venlafaxine (>6000 mg).
• Treatment involved intravenous hydration with normal saline and oral activated charcoal with sorbitol.
• Monitoring of arterial blood gas, lactate levels, and anion gap.

Main Results:

• The patient presented with elevated anion gap (22 mEq/L) and lactate (8.6 mmol/L).
• Lactic acidosis resolved within 24 hours following treatment, with lactate levels decreasing to 5.6 mmol/L after 4 hours.
• Venlafaxine was identified as the most probable cause in the absence of other contributing factors.

Conclusions:

• Venlafaxine overdose can cause type B lactic acidosis.
• Prompt supportive care, including hydration and activated charcoal, can effectively manage venlafaxine-induced lactic acidosis.