AHFS Class:

• Analgesics and Antipyretics, Miscellaneous 28:08.92

Generic Name(s):

• Sodium Thiosalicylate

Sodium thiosalicylate is an analgesic agent.

Although sodium thiosalicylate may be used in the symptomatic treatment of osteoarthritis, rheumatic fever, muscular pain, musculoskeletal disorders, and acute gout, there are no published studies to date to support the safety and efficacy of the drug in the treatment of these conditions.

One manufacturer states that data from an unpublished study in a small number of patients indicate that sodium thiosalicylate therapy decreased pain and increased mobility in patients with osteoarthritis but had no therapeutic effects in patients with rheumatoid arthritis; the study was not controlled and the methodologies for measurement of pain and mobility were not described.

Administration

Sodium thiosalicylate is administered by IM or slow IV injection. To minimize pain associated with IM administration of the drug, IM injections should be given deeply into a relatively large muscle mass (e.g., gluteus maximus, mid-lateral thigh) and injection sites should be alternated.

Dosage

In the symptomatic treatment of osteoarthritis, the usual adult IM or IV dosage of sodium thiosalicylate is a 100-mg dose 3 times weekly for several weeks and then once weekly; the usual course of treatment consists of a total dosage of about 2.5 g. A second course of treatment may be given, if necessary, after an interval of 1-2 weeks.

In the symptomatic treatment of rheumatic fever, the usual initial adult IM or IV dosage is 100-150 mg every 4-6 hours for 3 days, followed by 100 mg twice daily until the patient is asymptomatic.

The usual adult IM or IV dosage for the symptomatic treatment of muscular pain and musculoskeletal disorders is 50-100 mg once daily or once every other day.

In the symptomatic treatment of acute gout, the usual adult IM or IV dosage is 100 mg every 3-4 hours for 2 days, followed by 100 mg once daily until the patient is asymptomatic.

Information on the adverse effects of sodium thiosalicylate is lacking. Since sodium thiosalicylate is structurally and pharmacologically related to the salicylates and appears to share the toxic potentials of the salicylates, the usual precautions of salicylate administration should be observed. (See Cautions in the Salicylates General Statement 28:08.04.24.)

Precautions and Contraindications

Sodium thiosalicylate injection is contraindicated in patients with known hypersensitivity to the drug or any ingredient in the formulation. The drug may also be contraindicated in patients with known hypersensitivity to salicylates; one manufacturer recommends sensitivity testing in these patients with an IM dose of 2.5-5 mg of sodium thiosalicylate before administration of a full dose of the drug.

Pregnancy and Lactation

Pregnancy

Safe use of sodium thiosalicylate during pregnancy has not been established.

Lactation

Safe use of sodium thiosalicylate during lactation has not been established.

Pharmacology

Sodium thiosalicylate reportedly has analgesic and antipyretic activity; however, there are no published studies to date that document these effects in humans. It has not been established whether sodium thiosalicylate has anti-inflammatory effects in humans; however, in one study in animals, the drug was more effective than sodium salicylate, on an equimolar basis, in reducing experimentally induced inflammation.

Pharmacokinetics

Several manufacturers state that sodium thiosalicylate is readily absorbed and is detected in the blood within 1.5 hours following IM administration; however, there are no published studies to date on the absorption, distribution, or elimination of sodium thiosalicylate.

Chemistry and Stability

Chemistry

Sodium thiosalicylate, the sodium salt of thiosalicylic acid, is an analgesic agent. The drug is formed by substitution of a sulfhydryl group for the hydroxyl group in salicylic acid.

Sodium thiosalicylate is soluble in water and has a pK_a of 3.62. Each gram of sodium thiosalicylate contains approximately 5.7 mEq of sodium. Sodium thiosalicylate injection is a clear, light-amber, sterile solution of sodium thiosalicylate in water for injection; the injection has a pH of 7-8.5 and may contain benzyl alcohol.

Stability

Sodium thiosalicylate injection should be stored at a temperature less than 40°C, preferably between 15-30°C. A slight precipitate may form in sodium thiosalicylate injection due to oxidation; if the precipitate does not redissolve when the container is shaken well, the injection should not be used.