SAT: TETANUS ANTITOXIN SERUM

Purified tetanus antitoxin serum (SAT) is a colorless or pale yellow solution derived from the plasma of immunized horses and contains specific antibodies against tetanus toxin.

COMPOSITION:

Tetanus antitoxin globulin — 1,500 IU
Sodium chloride (buffer) — 0.85–0.9%
Thimerosal (preservative) — ≤ 0.01%

INDICATIONS:

Prophylaxis of tetanus following wounds or animal bites.
Treatment of patients with clinically manifest tetanus.

CONTRAINDICATIONS:

Hypersensitivity to equine serum.
History of allergic reactions to equine-derived tetanus antitoxin serum. If passive immunization is essential in these patients, human tetanus immunoglobulin (TIG) should be used.

DOSAGE AND ADMINISTRATION:

Route of administration: Intramuscular injection.

Dosage:

Prophylaxis following injury:

The usual prophylactic dose for adults and children is 1,500 IU, administered as soon as possible after injury. The dose may be doubled for tetanus-prone wounds, delayed initiation of prophylaxis, or individuals with a very large body habitus.

Treatment of tetanus:

Although the optimal effective therapeutic dose for tetanus has not been established, the recommended dosage is as follows:

Neonatal tetanus: 5,000–10,000 IU.

Children and adults: 50,000–100,000 IU; administer half of the dose subcutaneously and the remaining half intramuscularly.

ADVERSE REACTIONS:

Following administration of SAT, mild reactions such as fatigue, pain, tenderness, muscle stiffness, and erythema commonly occur at the injection site and may persist for several hours. Mild fever, rash or generalized erythema, angioedema, and injection-site inflammation may occur but are uncommon. These reactions are generally mild and resolve spontaneously. Patients should monitor symptoms and seek medical advice when necessary.
Mild systemic and local reactions may occur after SAT administration, including fatigue, low-grade fever, or allergic manifestations such as pruritus, edema, urticaria, rash, arthralgia, generalized erythema spreading from the injection site, angioedema, and local inflammation; these reactions are uncommon.
Hypersensitivity to SAT may manifest as severe local or systemic reactions, particularly after repeated administration and in individuals with a history of allergy. Patients with an atopic predisposition or repeated exposure to equine serum are at increased risk of urticaria, pruritus, edema, nephritis, and, rarely, nephrotic syndrome or serum sickness. Severe anaphylactic reactions may occur, although they are rare.
Allergic reactions may occur immediately after injection, several hours or days later, or even 7–10 days after administration. Any adverse reactions associated with SAT should be reported promptly to a physician.

DRUG INTERACTIONS:

Purified SAT does not interfere with the active immune response to tetanus vaccine and may therefore be administered concurrently with tetanus vaccine. However, the two products must not be mixed in the same syringe or administered at the same injection site, because SAT may neutralize the tetanus toxoid in the vaccine.
Purified SAT may reduce the immune response to certain live attenuated viral vaccines, including measles, mumps, and rubella vaccines. These vaccines should therefore be administered at least 3 months after SAT. If earlier vaccination is necessary and there is no clear serological evidence of an immune response, an additional dose of the live vaccine may be given 3 months after the last vaccination, in accordance with the immunization schedule.
Immunoglobulin preparations do not interfere with the immune response to orally administered vaccines, such as oral poliovirus vaccine (OPV) and oral typhoid vaccine (Ty21a). These vaccines may be administered concurrently with, before, or after purified SAT.

PRECAUTIONS AND WARNINGS:

Obtain a thorough allergy history and ensure that appropriate medications and equipment for the management of anaphylaxis are readily available.
Skin testing is not routinely performed in all patients indicated for SAT. When skin testing is considered necessary (e.g., a history of allergy to previously administered antisera, anaphylaxis to multiple other allergens, drug allergy, or allergic diseases such as allergic rhinitis or bronchial asthma), it must be performed in a clinical allergy and immunology department or by physicians trained in the prevention, diagnosis, and management of anaphylaxis, in accordance with Circular No. 51/2017/TT-BYT dated 29 December 2017.
In patients who have not previously received equine serum, the entire dose may be administered as a single injection.
Patients with a positive hypersensitivity test must undergo desensitization using the Besredka method: administer 0.1 mL intramuscularly or subcutaneously and observe for 30 minutes. If no reaction occurs, administer 0.25 mL and observe for another 30 minutes. If no reaction occurs, administer the remaining dose.
Antihistamines may be administered before serum injection when necessary.
In patients with thrombocytopenia or coagulation disorders, intramuscular injection is contraindicated unless the anticipated benefit outweighs the risk. Administration in such cases must be based on the physician’s assessment.
SAT contains thimerosal as a preservative. Particular caution should be exercised in patients with previous mercury exposure from other sources, including food, medicines, or vaccines.

USE DURING PREGNANCY AND LACTATION:

Pregnancy: SAT should not be administered during pregnancy unless the anticipated benefits outweigh the potential risks and a physician has been consulted.

Lactation: SAT is not contraindicated during breastfeeding. However, medical advice should be sought because information on whether tetanus antitoxin serum is excreted into human breast milk is currently unavailable.

OVERDOSAGE AND MANAGEMENT:

Overdosage: No data are available on SAT overdose. Do not exceed the prescribed dose.

Management of overdose: Report any adverse reactions occurring after serum administration to a physician. No cases identified as overdose have been reported.