The Food and Drug Administration has approved sodium thiosulfate injection (Pedmark) to decrease the risk of ototoxicity associated with cisplatin use in children who are at least one month old who have localized nonmetastatic solid tumors.

Cisplatin-induced ototoxicity causes irreversible damage to hair cells in the cochlea. Sodium thiosulfate interacts directly with cisplatin, creating an inactive platinum species. In addition, sodium thiosulfate can enter cells and cause intracellular effects such as an increase in antioxidant glutathione levels and inhibition of intracellular oxidative stress. Both activities may contribute to the drug's ability to reduce the risk of ototoxicity.

The efficacy of sodium thiosulfate was evaluated in two multicenter, randomized, controlled, open-label studies with 114 patients in one study and 125 patients in the other. Patients received either sodium thiosulfate following cisplatin or cisplatin alone. The incidence of hearing loss was lower in the groups that received sodium thiosulfate and cisplatin compared with cisplatin alone. In one trial, 39% of those receiving sodium thiosulfate and cisplatin experienced hearing loss compared with 68% in the cisplatin group. In the second trial, hearing loss was experienced by 44% of those receiving sodium thiosulfate and cisplatin compared with 58% of those receiving cisplatin alone.

The most common adverse effects of sodium thiosulfate treatment are vomiting, nausea, decreased hemoglobin, hypernatremia, and hypokalemia. Hypersensitivity reactions can also occur.

Pedmark's labeling specifies that the drug should be infused six hours after completion of the cisplatin infusion and at least 10 hours before the next cisplatin infusion. The dose is based on body surface area using actual-not estimated-body weight. Nurses should weigh the child frequently to obtain a current weight. To prevent nausea and vomiting, nurses should administer an antiemetic before each infusion. Patients with sulfite sensitivity may have hypersensitivity reactions to sodium thiosulfate. If the child experiences a hypersensitivity reaction, the nurse should administer antihistamines and possibly glucocorticoids before each subsequent infusion. The nurse should assess the child for severity of adverse effects, monitor laboratory work, and observe for signs and symptoms of hypernatremia and hypokalemia. Sodium thiosulfate should be withheld if serum sodium is greater than 145 mmol/L. The labeling has specific recommendations for modifying the drug's dose in the case of severe reactions. Nurses should consult with the prescriber to adjust the dose as needed.

For complete prescribing information for Pedmark, go to http://www.accessdata.fda.gov/drugsatfda_docs/label/2022/212937s000lbl.pdf.