Isosulfan Blue

Isosulfan blue injection 1% upon subcutaneous administration, delineates lymphatic vessels draining the region of injection. It is an adjunct to lymphography in: primary and secondary lymphedema of the extremities; chyluria, chylous ascites or chylothorax; lymph node involvement by primary or secondary neoplasm; and lymph node response to therapeutic modalities.

Isosulfan blue injection 1% is to be administered subcutaneously, one-half (1/2) mL into three (3) interdigital spaces of each extremity per study. A maximum dose of 3 mL (30 mg) isosulfan blue is, therefore, injected.

Life-threatening anaphylactic reactions (respiratory distress, shock, angioedema) have occurred after isosulfan blue 1% administration. Reactions are more likely to occur in patients with a history of bronchial asthma, allergies, drug reactions or previous reactions to triphenylmethane dyes. Monitor patients closely for at least 60 minutes after administration of isosulfan blue 1%. Trained personnel should be available to administer emergency care including resuscitation.

The admixture of isosulfan blue 1% (with local anesthetics (i.e. lidocaine)) in the same syringe results in an immediate precipitation of 4 to 9% drug complex. Use a separate syringe to administer a local anesthetic.

Isosulfan blue 1% interferes with measurements of oxygen saturation in peripheral blood by pulse oximetry and can cause falsely low readings. The interference effect is maximal at 30 minutes and minimal generally by four hours after administration. Arterial blood gas analysis may be needed to verify decreased arterial partial pressure of oxygen.

Isosulfan blue 1% may also cause falsely elevated readings of methemoglobin by arterial blood gas analyzer. Therefore, co-oximetry may be needed to verify methemoglobin level.

Hypersensitivity Reactions: Case series report an overall incidence of hypersensitivity reactions in approximately 2% of patients. Life-threatening anaphylactic reactions have occurred. Manifestations include respiratory distress, shock, angioedema, urticaria, pruritus. A death has been reported following administration of a similar compound employed to estimate the depth of a severe burn. Reactions are more likely to occur in patients with a personal or family history of bronchial asthma, significant allergies, drug reactions or previous reactions to triphenylmethane dyes [see Warnings and Precautions (5)].

Laboratory Tests: Isosulfan blue 1% interferes with measurements of oxygen saturation by pulse oximetry and of methemoglobin by gas analyzer [see Warnings and Precautions (5)].

Skin: transient or long-term (tattooing) blue coloration.

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when isosulfan blue 1% is administered to a nursing mother.

Safety and effectiveness of isosulfan blue 1% in children have not been established.

Following subcutaneous administration, isosulfan blue 1% binds to serum proteins and is picked up by the lymphatic vessels. Thus, the lymphatic vessels are delineated by the blue dye.

Up to 10% of the subcutaneously administered dose of isosulfan blue 1% is excreted unchanged in the urine in 24 hours in human.

Long-term studies in animals have not been performed to evaluate the carcinogenic potential of isosulfan blue 1%. Reproduction studies in animals have not been conducted and, therefore, it is unknown if a problem concerning mutagenesis or impairment of fertility in either males or females exists.

Pregnancy Category C. Animal reproduction studies have not been conducted with isosulfan blue 1%. It is not known whether isosulfan blue 1% can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Isosulfan blue 1% should be given to a pregnant woman only if clearly needed.