Successful Rapid Desensitization to Glatiramer Acetate: Report of 2 Cases

Glatiramer acetate (GA) is a generally safe, effective and well tolerated drug, but discontinuation of treatment may be required in up to 10% of cases due to severe systemic postinjection reactions. Notably, there are only sparse data on desensitization protocols for patients with hypersensitivity to GA.

We present 2 cases of successful desensitization to Glatiramer acetate (GA)

A 51-year-old female with MS was treated with GA for the last   four years without any adverse reaction. Suddenly, after GA injection she developed generalized urticaria. Skin prick (SPT) and intradermal (ID) testing to GA and mannitol (an inactive ingredient of Copaxone^R with allergenic potential) was performed. Histamine and NaCl was used as positive and negative control. SPT showed a borderline reaction to GA (wheal diameter=3mm) at a concentration of 20mg/ml, while a positive reaction was shown on intradermal skin testing at a concentration of 0,002mg/ml. SPT and ID testing to mannitol, were negative. A procedure of desensitization to GA was carried out in an outpatient setting under close medical supervision. Increasing dosages of GA were administered subcutaneously every 15 minutes, at a starting dose of 20ng followed by gradual dose escalation up to 20mg. The entire desensitization procedure lasted 3 hours and 15 minutes. The desensitization procedure was well tolerated with no adverse events. The patient was able to resume GA treatment with no recurrence during a follow up period of 12 months.

A 39 years old female was treated for MS with GA for 3 months without any adverse reaction until her last injection. Immediately after administration of Copaxone^R she experienced, life threatening anaphylaxis with urticaria, angioedema, abdominal cramps, dyspnea, drop in blood pressure and loss of consciousness. The patient was referred to our department for further evaluation. Allergy testing, with the already described procedure, revealed positive ID test at 0,002mg/ml. We used exactly the same protocol of desensitization in an inpatient basis. During the process she experienced anaphylactic reactions were successfully treated. After 2 days the patient was able to tolerate 20mg of GA. The patient receives GA daily after 5 months without any adverse event.

These 2 cases illustrates that rapid subcutaneous desensitization may allow continuation of GA treatment in patients with a history of systemic reactions