ATG

ATG antithymocyte globulin.

---

ATG,

abbreviation for antithymocyte globulin.

---

lymphocyte immune globulin (antithymocyte globulin equine, ATG, ATG equine, LIG)

Atgam

Pharmacologic class: Immunoglobulin

Therapeutic class: Immunosuppressant

Pregnancy risk category C

FDA Boxed Warning

• Give drug under supervision of physician experienced in immunosuppressive therapy for treatment of renal transplant or asplastic anemia patients, in facility with adequate laboratory and supportive resources

Action

Unknown. Thought to inhibit cell-mediated immune response by altering function of or eliminating T lymphocytes in circulation.

Availability

Injection: 50 mg /ml in 5-ml ampules

⊘Indications and dosages

➣ To prevent acute renal allograft rejection

Adults: 15 mg/kg/day I.V. for 14 days, then switch to alternate-day dosing for 14 days (for a total of 21 doses in 28 days). Give first dose within 24 hours of transplantation.

➣ Acute renal allograft rejection

Adults and children: 10 to 15 mg/kg/day I.V. for 14 days, then may switch to alternate-day dosing for 14 days (for a total of 21 doses in 28 days). Start therapy at first sign of rejection.

➣ Aplastic anemia in patients ineligible for bone marrow transplantation

Adults: 10 to 20 mg/kg/day I.V. for 8 to 14 days; then may give additional alternate-day doses for a total of up to 21 doses in 28 days

Off-label uses

• Bone marrow, liver, and heart transplantation
• Multiple sclerosis
• Myasthenia gravis
• Scleroderma

Contraindications

• History of severe systemic reaction to lymphocyte immune globulin or other equine preparation

Precautions

Use cautiously in:
• severe renal or hepatic disease
• pregnant or breastfeeding patients
• children.

Administration

☞ Know that drug should be given only by health care professionals experienced in immunosuppressive therapy for treating aplastic anemia or renal transplant patients, in facilities equipped and staffed with adequate laboratory and supportive resources.
☞ Because of high risk of anaphylaxis, perform intradermal skin test before first dose. Inject 0.1-ml dose of 1:1,000 dilution of LIG intradermally; a control test using 0.9% sodium chloride injection is injected contralaterally. Observe site every 15 to 20 minutes during first hour after injection, and monitor patient for systemic manifestations. Local reaction of 10 mm or greater with wheal, erythema, or both (with or without pseudopod formation and itching or marked local swelling) indicates positive test (which warrants consideration of alternate therapy). Systemic reaction (such as tachycardia, dyspnea, hypotension, or anaphylaxis) precludes LIG therapy.
• Premedicate with antipyretic, antihistamine, or corticosteroid, as prescribed, to minimize reactions.
• For I.V. infusion, dilute prescribed dose in 250 to 1,000 ml of 0.45% or 0.9% sodium chloride injection. (Don't dilute in dextrose solutions or highly acidic solutions.) Final concentration shouldn't exceed 4 mg/ml. Infuse total daily dose over at least 4 hours.
• When adding drug to infusion container, invert container so air doesn't enter. Gently swirl or rotate container to mix solution.
• Using in-line filter with pore size of 0.2 to 1 micron, infuse into central vein, shunt, or arteriovenous fistula over at least 4 hours.
• Be aware that drug is usually given concurrently with azathioprine and corticosteroids when used for allograft rejection.

Route	Onset	Peak	Duration
I.V.	Immediate	5 days	Unknown

Adverse reactions

CNS: malaise, agitation, headache, dizziness, weakness, syncope, encephalitis, seizures

CV: hypotension, hypertension, chest pain, bradycardia, tachycardia, cardiac irregularities, phlebitis, myocarditis, thrombophlebitis, heart failure

EENT: periorbital edema

GI: nausea, vomiting, diarrhea, stomatitis

Hematologic: leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia

Hepatic: hepatosplenomegaly

Metabolic: hyperglycemia

Musculoskeletal: joint pain or stiffness, myalgia, back pain

Respiratory: dyspnea, pleural effusion

Skin: rash, pruritus, urticaria, diaphoresis, night sweats

Other: burning soles and palms, fever, chills, pain at infusion site, edema, lymphadenopathy, hypersensitivity reactions including serum sickness and anaphylaxis

Interactions

Drug-diagnostic tests. Creatinine, glucose, hepatic enzymes: increased values

Hemoglobin, platelets, white blood cells: decreased values

Kidney and liver function tests: abnormal results

Patient monitoring

☞ During infusion, watch for signs and symptoms of hypersensitivity reaction, such as rash, respiratory distress, or chest, flank, or back pain. Be aware that this reaction may occur even with a negative skin test.
☞ Discontinue drug if renal transplant patient develops signs or symptoms of anaphylaxis or severe thrombocytopenia or leukopenia.
• Be aware that product derives from equine and human blood components and may transmit infections.
• Monitor for signs and symptoms of infection, such as fever, malaise, and sore throat (caused by immunosuppression).

Patient teaching

☞ Tell patient to immediately report adverse reactions during infusion (such as pain at infusion site) as well as systemic complaints (such as easy bruising or bleeding or signs of hypersensitivity reaction).
• Instruct patient to avoid sources of infection, such as people with known infections. Tell him to promptly report signs or symptoms of infection.
☞ Advise patient to immediately report evidence of serum sickness, including fever, joint pain, nausea, vomiting, lymphadenopathy, and rash.
☞ Caution female patient not to take drug if she is pregnant.
• Tell female patient to inform prescriber if she is breastfeeding.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the tests mentioned above.

---

ATG

1 Angiotensinogen 2 Antithymocyte globulin, see there 3. Antithyroglobulin–antibodies