Ecallantide (Kalbitor) is a prescription medication administered by injection. It functions as a kallikrein inhibitor, a class of drugs designed to modulate bodily processes. This recombinant protein, composed of 60 amino acids, interacts with specific enzymes. It is provided as a clear, colorless solution for subcutaneous use.
Medical Use for Ecallantide
Ecallantide is indicated for the acute treatment of attacks associated with hereditary angioedema (HAE). HAE is a rare genetic condition characterized by recurrent episodes of severe swelling. This swelling can affect the skin, gastrointestinal tract, and respiratory system. Such attacks can be debilitating and, particularly when affecting the airways, potentially life-threatening.
The medication is approved for patients aged 12 years and older experiencing acute HAE attacks. Ecallantide treats active swelling episodes; it is not a preventative or prophylactic therapy. Its purpose is to alleviate symptoms once an attack has begun.
Mechanism of Action
Hereditary angioedema attacks arise from dysregulation in the body’s contact system, primarily due to a deficiency or dysfunction of C1-esterase inhibitor (C1-INH). This deficiency permits uncontrolled activation of plasma kallikrein, an enzyme involved in the kallikrein-kinin system. Plasma kallikrein then acts upon high-molecular-weight kininogen, leading to the excessive production of bradykinin.
Bradykinin is a potent peptide that causes blood vessels to dilate and become more permeable, resulting in fluid leakage into surrounding tissues. This fluid leakage is directly responsible for the characteristic swelling and pain experienced during an HAE attack. Ecallantide works by directly inhibiting plasma kallikrein. It binds to the enzyme, effectively blocking its active site.
By blocking plasma kallikrein, ecallantide prevents the conversion of kininogen into bradykinin. This action reduces bradykinin levels, thereby mitigating the increased vascular permeability that drives the swelling. This targeted inhibition helps to stop the progression of an acute HAE attack.
Administration and Dosing
Ecallantide is administered via subcutaneous injection. The standard recommended dose for treating an acute HAE attack is 30 mg. This dose is typically divided into three separate 10 mg injections, given in one sitting.
The injections can be administered into the fatty tissue of the abdomen, thigh, or upper arm. Each injection site should be separated by at least 5 centimeters. If the initial attack symptoms persist, an additional 30 mg dose may be administered within a 24-hour period.
Ecallantide must be administered by a healthcare professional. It is not intended for self-administration and should only be given in a medical setting prepared to manage potential adverse reactions.
Potential Side Effects and Safety Information
Common side effects include headache, nausea, fatigue, and various injection site reactions such as pain, redness, swelling, bruising, or itching. Other less common effects include diarrhea, upper respiratory tract infections, and pyrexia.
A serious concern is the risk of anaphylaxis, a severe, potentially life-threatening allergic reaction. Anaphylaxis can manifest with symptoms such as difficulty breathing, hives, swelling of the face, lips, tongue, or throat, dizziness, rapid heartbeat, and a sudden drop in blood pressure. In clinical studies, 3% to 4% of patients receiving subcutaneous ecallantide experienced anaphylaxis.
Due to this risk, ecallantide carries an FDA black box warning, which is the agency’s strongest safety alert. This warning underscores the requirement for the medication to be administered solely by a healthcare professional in a medical facility. The facility must be equipped to promptly recognize and manage anaphylaxis, ensuring patient safety.