The vitamin B12 analog cobinamide is an effective hydrogen sulfide antidote in a lethal rabbit model

Abstract

Background and purpose. Hydrogen sulfide (H₂S) is a highly toxic gas for which no effective antidotes exist. It acts, at least in part, by binding to cytochrome c oxidase, causing cellular asphyxiation and anoxia. We investigated the effects of three different ligand forms of cobinamide, a vitamin B12 analog, to reverse sulfide (NaHS) toxicity. Methods. New Zealand white rabbits received a continuous intravenous (IV) infusion of NaHS (3 mg/min) until expiration or a maximum 270 mg dose. Animals received six different treatments, administered at the time when they developed signs of severe toxicity: Group 1—saline (placebo group, N = 9); Group 2—IV hydroxocobalamin (N = 7); Group 3—IV aquohydroxocobinamide (N = 6); Group 4—IV sulfitocobinamide (N = 6); Group 5—intramuscular (IM) sulfitocobinamide (N = 6); and Group 6—IM dinitrocobinamide (N = 8). Blood was sampled intermittently, and systemic blood pressure and deoxygenated and oxygenated hemoglobin were measured continuously in peripheral muscle and over the brain region; the latter were measured by diffuse optical spectroscopy (DOS) and continuous wave near infrared spectroscopy (CWNIRS). Results. Compared with the saline controls, all cobinamide derivatives significantly increased survival time and the amount of NaHS that was tolerated. Aquohydroxocobinamide was most effective (261.5 ± 2.4 mg NaHS tolerated vs. 93.8 ± 6.2 mg in controls, p < 0.0001). Dinitrocobinamide was more effective than sulfitocobinamide. Hydroxocobalamin was not significantly more effective than the saline control. Conclusions. Cobinamide is an effective agent for inhibiting lethal sulfide exposure in this rabbit model. Further studies are needed to determine the optimal dose and form of cobinamide and route of administration.

Keywords:

• Heart
• Lung
• Muscle
• CNS/Psychological

View correction statement:

Corrigendum

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.

Supported by Funding Sources: CounterACT NIH # 1U54 NS079201, CounterACT R21 NS72105, NIH U01-NS058030, LAMMP, LAMMP #445474-30136, AMRMC W81XWH-12-2-0098.