Role of Biologics (Omalizumab) in Chronic Urticaria

Introduction:

Omalizumab, an antibody derived from murine blood, acts against human immunoglobulin E (IgE). This drug was approved by FDA (Food and Drug Administration) for use in chronic idiopathic urticaria. It can be used in a patient who does not respond to approved doses of H1 antihistamines.

What Is Chronic Spontaneous Urticaria?

Chronic urticaria is characterized by the presence of hives or welts that persist for a minimum of six weeks, regardless of the presence of angioedema. It is also known as chronic idiopathic urticaria. While symptoms may go away after a few months, in half of the instances, they last for three to five years, and in 20 percent of cases, they last for over a decade. The most common cause of urticaria is histamine's impact on H1-receptors present in the cells called endothelial cells, which surround blood vessels. Histamine splits the cells, allowing tissue fluid to seep out and create a weal. Additionally, histamine affects sensory nerves, which can lead to itching and an erythematous flare.

What Are the Symptoms of Chronic Urticaria?

The symptoms of chronic urticaria include:

• Pruritus (itchy skin).

• Red or skin-colored welts.

• Angioedema (swelling in the lips, eyelids, and throat).

• Difficulty breathing.

What Are the Mechanisms of Action of Omalizumab in Chronic Urticaria?

Basophils and mast cells are the storehouses of various allergy-causing mediators. These mediators are released when IgE in the body binds to receptors present over these cells. Omalizumab inhibits this phenomenon of binding IgE to these cells. Omalizumab binds to free IgE in the body fluids with much higher affinity, thus preventing IgE binding to the receptors present over basophils and mast cells.

Omalizumab does not bind to already receptor-bound IgE or to the receptor directly. These binding characteristics allow Omalizumab to neutralize IgE-mediated responses without the release of allergy-causing mediators.

What Is Omalizumab’s Role in the Treatment of Urticaria?

When oral antihistamines are ineffective in treating chronic spontaneous urticaria, Omalizumab is meant to be the second line of treatment. Numerous other systemic therapies, including immunomodulating medications and systemic steroids, are also ineffective for many people.

What Are the Possible Risks of Using Omalizumab?

Around ten percent of individuals receiving Omalizumab experience headaches and injection site reactions, which include swelling, redness, discomfort, and itching. Those who might be allergic to Omalizumab or any of the ingredients in the injection vial should not take the medication. Anaphylaxis and other severe adverse events are extremely infrequent.

What Should One Inform the Physician Before the Administration of Omalizumab?

Do not get injected with Omalizumab if allergic to it or if one has:

• Latex allergy or any other allergies.

• Food allergy or seasonal allergies.

• Pollen allergies.

• History of anaphylaxis reactions.

• History of parasitic infections like giardia, hookworm, malaria, leishmaniasis, pinworm, toxoplasmosis, etc.

• Cancer or a previous history of cancer.

• Pregnant or planning for pregnancy.

• Breastfeeding or planning to breastfeed the baby.

Consult with the healthcare provider in case of the above issues.

What Are the Usage and Dosage of Omalizumab?

• In chronic idiopathic urticaria, subcutaneous injection of 150 to 300 mg is repeated every two to four weeks for 12 weeks.

• In the case of atopic dermatitis, systemic mastocytosis, and bullous urticaria, 150 to 300 mg subcutaneous injection two to four weekly.

• However, the treatment might be continued until the patient is symptomless.

How to Use Omalizumab?

• It should only be administered by the doctor in a medical facility.

• If a doctor thinks that a patient or caregiver can administer prefilled syringe injections, then they should be properly trained to prepare and administer the medication.

• Unless one is skilled at injecting themselves, one should not attempt self-injection.

• Prefilled syringes can be used for self-injection by children over the age of 12 with adult supervision.

• Follow the instructions on the label for the right way of preparation and administration of the drug.

• One or more injections are given subcutaneously (under the skin), one time every four weeks.

• A blood test is not required for people with chronic hives to determine the dosage.

• Without consulting with a physician, do not discontinue the other hive medications one is already on or cut back on their dosage.

• If the medicine is injected above the required dose, please inform the healthcare provider immediately.

Overdose:

The physician usually administers Omalizumab in the medical office setting, so there is less chance of overdose, but if an overdose is suspected, seek immediate medical help.

Special Consideration Before Administration:

• This drug should be administered by a physician or a healthcare professional who is trained in the recognition and treatment of anaphylaxis. Symptoms of systemic eosinophilia, along with clinical features of urticarial vasculitis, occur more often in patients who are on Omalizumab, which is usually reduced with oral corticosteroid dosage.

• Some patients have experienced some signs and symptoms, including joint pain, skin rashes, fever, and enlargement of the lymph node in the form of painful pea-shaped swelling in the axilla or groin areas. This usually occurs with an onset of one to five days after the first and subsequent injections of Omalizumab. Therapy should be discontinued if such symptoms occur.

What Are the Side Effects of Omalizumab?

• 12 percent of individuals treated with Omalizumab experienced injection site reactions, which include swelling, redness, discomfort, bruises, itching, bleeding, and urticaria.

• Omalizumab-associated anaphylaxis is seen in 0.2 % of patients. Around two hours of the observation period is needed for the first three injections and 30 minutes for subsequent injections.

• Malignant neoplasms were observed in 0.5 % of patients treated with Omalizumab compared to 0.2 % in patients not treated with Omalizumab. Some of the observed malignancies include breast, non-melanoma skin, prostate, melanoma, and parotid.

• Other side effects like nausea, sinusitis, upper respiratory tract infections, joint pain, headache, cough, etc., have been reported.

• In the case of pregnancy and lactation, it comes under category B medicine. It means Omalizumab can be given with caution.

• When used, Omalizumab can also cause anaphylaxis, a severe fatal allergic reaction. The anaphylactic reaction is characterized by bronchospasm with difficulty breathing, low blood pressure, fainting, and swelling of the tongue or throat.

• Fever, muscle aches, and rashes were observed in some people one to five days after receiving the injection. Consult with the healthcare provider if one gets these symptoms.

• Some people who received the injection had a high risk for parasite (worm) infections. The healthcare provider can do a stool examination to rule out the parasitic infection.

• Temporary symptoms like slurred speech, altered vision, or weakness in one side of the body also occurred in some patients who received the drug.

Conclusion:

Omalizumab is a biological medication in the form of a monoclonal antibody that attaches to immunoglobulin E (IgE) and inhibits basophils and mast cells from releasing mediators of inflammation. Omalizumab has demonstrated efficacy in children, adolescents, and adults with chronic urticaria, and it has proven to be the safest drug in treating patients with chronic urticaria.