Details About Overdose or Poisoning Generic Salt :: Hydroxocobalamin
Hydroxocobalamin
Drug Pharmacology ::
I. Pharmacology. Hydroxocobalaminand cyanocobalamin are synthetic forms of vitamin B12 that are used forthe treatment of pernicious anemia. Hydroxocobalamin has beenrecognized as an antidote for cyanide poisoning for over 45 years.Hydroxocobalamin immediately exchanges its hydroxyl group with freecyanide in the plasma to produce the nontoxic cyanocobalamin. Whenadministered to patients with cyanide poisoning, it rapidly improvesheart rate, systolic blood pressure, and acidemia. Well-designed animalstudies suggest enhanced antidotal efficacy when hydroxocobalamin isused with thiosulfate (see Thiosulfate, Sodium). In normal individuals,hydroxocobalamin has a plasma half-life of 3–20 hours. In patients withcyanide poisoning, the half-life is 14–24 hours, and the complexedcompound, cyanocobalamin, has a half-life of 6–12 hours. Oralabsorption is extremely poor; intranasal absorption occurs with verysmall doses.
Drug Indications ::
Indications
Treatment of acute cyanide poisoning or patients suspected to be athigh risk for cyanide poisoning (eg, smoke inhalation victims). Note: See VII, Formulations, below.
Prophylaxis against cyanide poisoning during nitroprusside infusion.
Drug Contra-Indications ::
III. Contraindications. Do not use in patients with a known hypersensitivity to this drug.
Drug Adverse Effects ::
IV. Adverse effects
After antidotal doses, body fluids become pink or red after hydroxocobalamin administration; this subsides within 2–7 days.
Nausea, vomiting, hypertension, and mild muscle twitching or spasms have been reported occasionally.
Allergic reactions have not been reported with acute intravenoustherapy for cyanide poisoning. However, allergic reactions have beenreported when it has been used for chronic IM therapy.
Use in pregnancy.No assigned FDA category; no reported experience with use duringpregnancy is available. This does not preclude its acute, short-termuse for a seriously symptomatic patient (see Table III–1), and it isprobably preferable to nitrite administration for cyanide poisoning.
Drug Lab Interactions ::
Drug or laboratory interactions.Coloration of the serum sample can interfere with the followinglaboratory tests: falsely decreased aspartate aminotransferase (AST)and creatinine and falsely increased magnesium and bilirubin. Considersampling for these prior to hydroxocobalamin administration.
Drug Dose Management ::
Dosage and method of administration. Note: Not available in the United States in a form sufficiently concentrated to provide an adequate dose for cyanide poisoning.
Acute cyanide poisoning.Give 5 g (children 70 mg/kg) by IV infusion over 30 minutes; 5 g ofhydroxocobalamin will neutralize approximately 40 mcmol/L (1.04 mg/L)of cyanide in blood. Doses up to 20 g have been used. Based on animalstudies, administration of hydroxocobalamin with thiosulfate (seeThiosulfate, Sodium) may improve outcome.
Prophylaxis during nitroprusside infusion. Administer 25 mg/h IV. Note:Low-strength (1 mg/mL) injection products in the United States maycontain the preservative parabens. Unknown safety if aparabens-containing product is used.
Drug Chemical Formulations ::
Formulations
A. Parenteral (United States).Hydroxocobalamin, 1 mg/mL IM; 10- and 30-mL vials (may containparabens). The United States does not have a formulation practical fortreating acute cyanide poisoning at this time. EMD Pharmaceuticals,Durham, NC, currently has licensing and is developing Cyanokit for theUS market.
Parenteral (non-United States).Cyanokit contains two of the following: 2.5-g vial of freeze-driedhydroxocobalamin, 100-mL vials of sterile 0.9% sodium chloride, and atransfer device. Designed for potential field use. Available in Europefrom Merck.
The suggested minimum stocking level (outside the United States)to treat a 70-kg adult for acute cyanide poisoning is three Cyanokits(equivalent to 15 g). Note that fires often involve several victims andwould require multiple kits.
