SODIUM THIOSULFATE Solution for injection Ref.[9522] Active ingredients: Thiosulfate

Treatment of cyanide poisoning must include immediate attention to airway patency, adequacy of oxygenation and hydration, cardiovascular support, and management of seizures. Consideration must be given to decontamination measures based on the route of exposure.

Sodium thiosulfate does not substitute oxygen therapy and must not delay the set up of the above measures.

The presence and extent of cyanide poisoning are often initially unknown. There is no widely available, rapid, confirmatory cyanide blood test. Treatment decisions must be made on the basis of clinical history and/or signs and symptoms of cyanide intoxication.

Cyanide poisoning may result from exposure to smoke from closed space fires, inhalation, ingestion, or dermal exposure. Sources of cyanide poisoning include hydrogen cyanide and its salts, cyanogens, including cyanogenic plants, aliphatic nitriles, or prolonged exposure to sodium nitroprusside.

Signs and symptoms of cyanide poisoning

Common signs and symptoms of cyanide poisoning include: nausea, vomiting, headache, altered mental status (e.g. confusion, disorientation), chest tightness, dyspnoea, tachypnoea or hyperpnoea (early), bradypnoea or apnoea (late), hypertension (early) or hypotension (late), cardiovascular collapse, seizures or coma, mydriasis, and plasma lactate concentration >8 mmol/L.

In the setting of multiple casualties such as terrorism or chemical disaster, panic symptoms including tachypnoea and vomiting may mimic early cyanide poisoning signs. The presence of altered mental status (confusion and disorientation) and/or mydriasis is suggestive of true cyanide poisoning.

Smoke inhalation

Not all smoke inhalation victims necessarily will have cyanide poisoning, but may present with burns, trauma, and exposure to additional toxic substances aggravating the clinical picture. Before sodium thiosulfate is administered, it is recommended to check affected persons for the presence of the following:

• exposure to fire smoke in an enclosed area
• soot present around mouth, nose and/or oropharynx
• altered mental status

In this setting hypotension and/or a plasma lactate concentration ≥ 10 mmol/L (higher than the one mentioned under signs and symptoms due to the fact that carbon monoxide contributes to lactic acidaemia) are highly suggestive of cyanide poisoning. In the presence of the above signs, treatment with sodium thiosulfate must not be delayed to obtain a plasma lactate concentration.

Sodium thiosulfate drug product may contain trace impurities of sodium sulfite. The presence of a trace amount of sulfites in this product should not deter administration of the drug for treatment of emergency situations, even if the patient is sulfite-sensitive.

Each 12.5 g dose of sodium thiosulfate contains approximately 3.6 g of sodium which is equivalent to 180% of the WHO recommended maximal daily intake of 2 g sodium for an adult.

Each 12.5 g dose of sodium thiosulfate also contains 115 mg of potassium and 140 mg of boric acid.

No interaction studies have been performed. Possible interaction may occur with hydroxocobalamin. Sodium thiosulfate should not be co-administered with hydroxocobalamin in the same injection line.

Pregnancy

There are no or limited amount of data (less than 300 pregnancy outcomes) from the use of sodium thiosulfate in pregnant women. Animals studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity (see section 5.3).

As a precautionary measure, it is preferable to avoid the use of sodium thiosulfate during pregnancy.

Breastfeeding

It is unknown whether sodium thiosulfate is excreted in human milk. A risk to the suckling child cannot be excluded.

Breast-feeding should be discontinued during treatment with sodium thiosulfate.

Fertility

There are no fertility data from the use of sodium thiosulfate in animals.

Not relevant.

There have been no controlled clinical trials conducted to systematically assess the adverse events profile of sodium thiosulfate.

The medical literature has reported the following adverse events in association with sodium thiosulfate administration. These adverse events were not reported in the context of controlled trials or with consistent monitoring and reporting methodologies for adverse events. Therefore, frequency of occurrence of these adverse events cannot be assessed.

^*Description of selected adverse reactions

Nausea and vomiting

In humans, rapid administration of concentrated solutions or solutions not freshly prepared, and administration of large doses of sodium thiosulfate have been associated with a higher incidence of nausea and vomiting. However, administration of 0.045 g sodium thiosulfate per kilogram up to a maximum of 15 g in a 10-15% solution over 10-15 minutes was associated with nausea and vomiting in 7 of 26 patients without concomitant cyanide intoxication.

Prolonged bleeding time

In a series of 11 human subjects, a single intravenous infusion of 50 mL of 50% sodium thiosulfate was associated with increases in clotting time 1-3 days after administration. However, no significant changes were observed in other hematological parameters.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the national reporting system: Yellow Card Scheme – Website: www.mhra.gov.uk/yellowcard.

Chemical incompatibility has been reported between sodium thiosulfate and hydroxocobalamin and these drugs should not be administered simultaneously through the same IV line. No chemical incompatibility has been reported between sodium thiosulfate and sodium nitrite, when administered sequentially through the same IV line.