Comparative effectiveness of methylene blue versus intravenous lipid emulsion in a rodent model of amlodipine toxicity

Abstract

Context: Calcium channel blocker (CCB) poisonings are the leading cause of death from cardiovascular medication-related overdoses. Current treatments (calcium salts, vasopressors, inotropes) are often insufficient. Intravenous lipid emulsion (ILE) and methylene blue (MB) show promise in treating CCB overdoses unresponsive to conventional therapy.

Objective: To compare the effectiveness of MB versus ILE in a rodent model of amlodipine (AML) poisoning with survival as the primary outcome and hemodynamic parameters as secondary outcomes.

Materials and methods: Sixty-four adult male albino rats were anesthetized and cannulated for non-invasive hemodynamic measurement. Rats received amlodipine intraperitoneally (42 mg/kg). We then divided the rats into four groups: AML only without antidote, AML followed by ILE (24.8 mL/kg over 10 min), AML followed by normal saline (an equivalent volume of ILE), and AML followed by IV MB (2 mg/kg over 5 min). They received study treatments at 5, 30, and 60 minutes from the start of the protocol and with observation for 2 hours.

Results: Survival time in ILE group was greater than in the control and NS groups. Differences between ILE and MB and between MB and NS were not significant. Hemodynamic parameters significantly increased in ILE group compared to the MB group at the 30, 60 and 120 min assessments but not after induction of AML poisoning and at 5 min assessment.

Conclusions: Survival was greatest in rats treated with ILE. Both MB and NS had little effect on survival when compared to control animals. Both ILE and MB improved hemodynamics.

Keywords:

• Methylene blue
• lipid emulsion
• amlodipine
• toxicity
• survival

Acknowledgements

The authors would like to thank Rofida Ashraf (British Medical Student) for her help with the manuscript preparation and English language editing.

Disclosure statement

No potential conflict of interest was reported by the authors.