Hydroxocobalamin

CYANOKIT

What it isHydroxylated vitamin B12 that binds cyanide as cyanocobalamin; cyanide poisoning and B12 deficiency.

Why this oneDetoxifies cyanide without inducing methemoglobinemia, favoring it in smoke inhalation where nitrites can impair oxygen delivery.

What limits itDeep-red discoloration of skin, urine, and plasma interferes with colorimetric laboratory tests and some dialysis equipment.

Principal riskIt turns fluids red and blocks colorimetric assays

Classes and tags

Therapeutic safety burden2 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk2 / 4

Legacy pregnancy categoryC

Defining liabilityRenal injury, hypertension and extensive laboratory interference

NO BOXED WARNINGS

FDA dosing	Population	Start	Target	Max
Known or suspected cyanide poisoning	Adults	5 g IV over 15 min (≈15 mL/min), once — one vial = complete starting dose	Second 5 g IV dose if needed per severity/response (over 15 min in extremis to 2 h)	10 g total

Renal Not studied; eliminated unchanged by kidneys — monitor renal function (BUN, creatinine) for 7 days

Hepatic Not studied

Pediatric safety and effectiveness not established; no dose adjustment in elderly

Give without delay if suspicion high, alongside airway, ventilation, oxygen, circulatory support and seizure management
Reconstitute 5 g vial with 200 mL 0.9% NaCl (LR or D5W if NaCl unavailable) via transfer spike; invert/rock, do not shake, ≥60 seconds
Inspect: discard if not dark red or particulate present
Separate IV line — do not co-infuse with sodium thiosulfate, sodium nitrite, ascorbic acid, other resuscitation drugs or blood products
Reconstituted solution stable up to 6 hours at ≤40°C; do not freeze
Collect pretreatment blood cyanide sample if possible (post-dose assay may be inaccurate) — do not delay treatment

Available strengths

Emergency patient management (airway, oxygenation, hydration, CV support, seizures)
Anaphylaxis/hypersensitivity — consider alternatives if known reaction to hydroxocobalamin or cyanocobalamin
Renal injury (acute renal failure, ATN, urine oxalate crystals) — monitor 7 days
Increased blood pressure — monitor during treatment
Interference with colorimetric lab tests and hemodialysis "blood leak" alarms
Photosensitivity — avoid direct sun while skin discolored
Draw blood cyanide sample before treatment

Pregnancy Human data insufficient; animal studies show fetal harm, but treatment may be lifesaving — do not withhold due to pregnancy

Lactation Breastfeeding not recommended during treatment; no data on when to safely restart

Hydroxocobalamin (CYANOKIT)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/unit	CostPlus
1 mg/mL	inj	per unit	$0.81/mL	not offered

Why can hydroxocobalamin be preferable to nitrites after smoke inhalation?
It does not induce methemoglobinemia.
What causes hydroxocobalamin’s interference with some laboratory tests?
Deep-red discoloration.