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a1-Proteinase Inhibitor (Monograph)

Brand names: Aralast, Prolastin, Zemaira
Drug class: Respiratory Tract Agents, Miscellaneous
VA class: RE900

Medically reviewed by on Mar 22, 2023. Written by ASHP.


A naturally occurring serine protease inhibitor.

Uses for a1-Proteinase Inhibitor

Congenital α1-Proteinase Inhibitor Deficiency

Replacement therapy in patients with congenital α1-proteinase inhibitor (also called α1-antitrypsin) deficiency and clinically evident emphysema.

Not indicated as therapy for patients with lung disease in whom congenital α1-proteinase inhibitor deficiency has not been established.

The American Thoracic Society and the European Respiratory Society (ATS/ERS) state that α1-proteinase inhibitor therapy does not confer benefit in, and is not recommended for, patients who have α1-proteinase-associated liver disease.

a1-Proteinase Inhibitor Dosage and Administration


IV Administration

Administer by IV infusion.

Administer IV infusions of Zemaira through an IV line using an administration set that contains an inline filter (pore size 5 µm).

Monitor infusion rate and clinical status (e.g., vital signs, infusion-related reactions) of the patient continuously throughout the infusion.

Administer with caution; percutaneous puncture with a needle contaminated with blood may transmit infectious agents. (See Risk of Transmissible Agents in Plasma-derived Preparations under Cautions.)


Vials of lyophilized α1-proteinase inhibitor and diluent should be at room temperature before reconstitution.

Reconstitute vials of lyophilized α1-proteinase inhibitor with manufacturer-supplied sterile water for injection without preservatives. Using the supplied transfer needle or device, add the appropriate volume of the supplied diluent to a vial containing α1-proteinase inhibitor. (See Table 1.) Swirl vial gently to ensure dissolution; do not shake.

Approximate amount (mg or g) of functionally active α1-proteinase inhibitor.

Manufacturer-supplied sterile water for injection without preservatives.

Table 1. Reconstitution of α1-Proteinase Inhibitor Preparations

α1-Proteinase Inhibitor Preparation

Dosage Strength Labeled on Vial

Diluent Volume


500 mg

25 mL


1 g

50 mL


500 mg

20 mL


1 g

40 mL


1 g

20 mL

Resultant solution of Aralast, Prolastin, or Zemaira contains not less than (NLT) 16 mg, NLT 20 mg, or approximately 50 mg of α1-proteinase inhibitor per mL, respectively.

For administration of large doses, several reconstituted vials may be pooled into an empty, sterile IV infusion container (e.g., empty IV bag or glass bottle) using aseptic technique.

Withdraw reconstituted solutions of Aralast and Prolastin from the vial using a filter needle provided by the manufacturer.

Reconstituted solutions contain no preservatives; administer within 3 hours after reconstitution.

Any unused solution should be discarded; discard administration equipment in accordance with biohazard waste procedures.

Rate of Administration

Administer Aralast at an infusion rate ≤0.08 mL/kg per minute.

Administer Zemaira at an infusion rate of approximately 0.08 mL/kg per minute.

Administer Prolastin at an infusion rate of ≥0.08 mL/kg per minute.

If adverse effects occur, reduce infusion rate or temporarily interrupt infusion until manifestations subside. Infusion may then be resumed at a rate tolerated by the patient.


Dosage of α1-proteinase inhibitor in mg is expressed in terms of functionally active α1-proteinase inhibitor, as determined by human neutrophil (Zemaira) or porcine pancreatic (Aralast, Prolastin) elastase inhibitory activity.

Number of mg of functionally active α1-proteinase inhibitor is indicated on the label of each vial.

Specific activity of functional α1-proteinase inhibitor in Aralast, Prolastin, or Zemaira is NLT 0.55, NLT 0.35, or NLT 0.7 mg, respectively, per mg of protein.


Congenital α1-Proteinase Inhibitor Deficiency

60 mg/kg by IV infusion once weekly.

Cautions for a1-Proteinase Inhibitor




Risk of Transmissible Agents in Plasma-derived Preparations

Potential vehicle for transmission of human viruses (i.e., hepatitis A [HAV] or C virus [HCV]; HIV-1 or HIV-2; parvovirus B19) or other infectious agents.

Despite stringent procedures (e.g., screening of plasma donors, application of a number of viral elimination/reduction steps) to prevent transmission of infectious agents, a risk of transmission still remains.

Risk of viral infection should be weighed against the benefits of α1-proteinase inhibitor therapy.

All infections thought possible to have been transmitted by α1-proteinase inhibitor products should be reported to the appropriate manufacturer.

Risk of Creutzfeldt-Jakob Disease

May carry a risk of transmitting the causative agent of Creutzfeldt-Jakob disease (CJD), although transmission via human blood, blood components, or plasma derivatives (including α1-proteinase inhibitor) has not been documented. CJD is a rare, but invariably fatal, degenerative disease of the CNS associated with a poorly understood transmissable agent.

There remains a theoretical risk that CJD can be transmitted through blood or blood products, although the risk is considered extremely remote.

Sensitivity Reactions

Hypersensitivity Reactions

Potential serious hypersensitivity reactions (e.g., anaphylactic or anaphylactoid reactions).

If acute hypersensitivity reactions (e.g., hives, generalized urticaria, tightness of the chest, dyspnea, wheezing, faintness, hypotension, anaphylaxis) occur, discontinue immediately and institute appropriate therapy as indicated (e.g., epinephrine, corticosteroids, maintenance of an adequate airway, oxygen).

General Precautions

Expansion of Plasma Volume

Transient expansion of plasma volume may occur during infusion; administer cautiously to patients at risk for circulatory overload.

Specific Populations


Category C.


Not known whether α1-proteinase inhibitor is distributed into milk. Caution advised if α1-proteinase inhibitor is used.

Pediatric Use

Safety and efficacy not established.

Hepatic Impairment

Use not recommended in patients with liver disease associated with α1-proteinase inhibitor deficiency.

Common Adverse Effects

Headache, somnolence, delayed fever, lightheadedness, dizziness, asthenia, injection site pain, paresthesia, pruritus.




Powder for Injection

Prolastin and Zemaira: ≤25°C; do not freeze.

Aralast: 2–8°C (may be exposed to ≤25°C); do not freeze. Use within 1 month of removing from refrigeration.


Advice to Patients


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Aralast and Zemaira must be obtained from specialty distributors; these preparations are not available through community pharmacies. For information regarding the Aralast distribution program, contact the manufacturer at 800-423-2090. For information regarding the distribution of Zemaira, contact the manufacturer at 866-ZEMAIRA (866-936-2472).

α1-Proteinase Inhibitor (Human)


Dosage Forms


Brand Names



For injection, for IV infusion only

number of mg indicated on label

Aralast (with sterile water for injection diluent, a double-ended transfer needle, and filter)


number of mg indicated on label

Prolastin (with sterile water for injection diluent, double-ended transfer needle, filter needle)


number of mg indicated on label

Zemaira (with sterile water for injection diluent, a double-ended transfer needle, and filter)

ZLB Behring

AHFS DI Essentials™. © Copyright 2024, Selected Revisions April 1, 2009. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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