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Interferon Beta-1b

Pronunciation: IN-ter-FEER-on BAY-ta
Class: Immunomodulator

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Trade Names

Betaseron
- Powder for injection, lyophilized 0.3 mg

Pharmacology

Unknown; however, the biologic response–modifying properties are mediated through the interactions of interferon beta-1b with specific cell receptors found on the surface of human cells. Binding to these receptors induces the expression of a number of interferon-induced gene products that are believed to be mediators of the drug's biological action.

Pharmacokinetics

Absorption

T _max is 1 to 8 h. Mean C _max is 40 units/mL. Bioavailability is approximately 50% (subcutaneous).

Distribution

Mean Vd _ss is 0.25 to 2.88 L/kg.

Elimination

Mean t _½ is 8 min to 4.3 h.

Indications and Usage

To reduce the frequency of clinical exacerbations of relapsing-remitting multiple sclerosis in ambulatory patients.

Contraindications

History of hypersensitivity to natural or recombinant interferon beta, human albumin, or any other component of formulation.

Dosage and Administration

Adults

Subcutaneous Titrate to 0.25 mg every other day over a 6-wk period according to the following schedule: wk 1 and 2, 0.0625 mg every other day; wk 3 and 4, 0.125 mg every other day; wk 5 and 6, 0.1875 mg every other day; wk 7 and on, 0.25 mg every other day.

General Advice

Reconstitute powder using supplied diluent only. Swirl vial gently to dissolve. Do not shake vial.
Reconstituted solution should be clear and colorless.
Do not administer if particulate matter, cloudiness, or discoloration is noted.
Administer immediately after reconstitution, or refrigerate and use within 3 h.
Withdraw prescribed dose into syringe for injection.
Administer via subcutaneous route only. Not for intradermal, IM, or IV administration.
Rotate injection sites (eg, buttocks, thighs, abdomen, back of arms). Use a different area from where last injection was administered. Do not inject into areas where skin is tender, bruised, red, or hard.
Vials contain no preservative. Discard any unused portion. Do not combine unused portions.
Do not mix with other drug solutions.

Storage/Stability

Store unopened vials at controlled room temperature (59° to 86°F). May store reconstituted solution in refrigerator for up to 3 h. Do not freeze.

Drug Interactions

Zidovudine

Plasma levels of zidovudine may be elevated, increasing the pharmacologic effects and adverse reactions.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypertension (6%); cardiomyopathy, deep vein thrombosis, pulmonary embolism (postmarketing).

CNS

Headache (50%); depression (30%); insomnia (21%); incoordination (17%); ataxia, confusion, convulsion, depersonalization, emotional lability, paresthesia, psychotic symptoms (postmarketing).

Dermatologic

Rash (21%); skin disorder (10%); pruritus, skin discoloration, urticaria (postmarketing).

Endocrine

Hyperthyroidism, hypothyroidism, thyroid dysfunction (postmarketing).

GI

Abdominal pain (16%); pancreatitis, vomiting (postmarketing).

Genitourinary

Urinary urgency (11%); metrorrhagia (9%); impotence (8%); urosepsis, UTI (postmarketing).

Hematologic-Lymphatic

Decreased lymphocytes (86%); leukopenia (18%); decreased neutrophils, decreased WBC (13%); lymphadenopathy (6%); anemia, thrombocytopenia (postmarketing).

Hepatic

Hepatitis, increased gamma-glutamyltranspeptidase (postmarketing).

Lab Tests

Increased ALT (12%); increased AST (4%).

Local

Injection-site reaction (78%); injection-site inflammation (42%); injection-site pain (16%); injection-site hypersensitivity, injection-site necrosis (4%); injection-site edema, injection-site mass (2%).

Metabolic-Nutritional

Anorexia, hyperuricemia, hypocalcemia; increased triglyceride, weight decrease (postmarketing).

Musculoskeletal

Hypertonia (40%); myalgia (23%).

Respiratory

Dyspnea (6%); bronchospasm, pneumonia (postmarketing).

Miscellaneous

Flu-like symptoms (57%); asthenia (53%); neutralizing antibodies (45%); pain (42%); fever (31%); chills (21%); peripheral edema (12%); chest pain (9%); malaise (6%); fatal capillary leak syndrome (postmarketing).

Precautions

Monitor

CBC and differential WBC counts, platelet counts, and blood chemistries, including LFTs, are recommended at 1, 3, and 6 mo following initiation of therapy and periodically thereafter. Thyroid function tests are recommended every 6 mo in patients with history of thyroid dysfunction.

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Albumin

Product contains albumin, a derivative of human blood; therefore, there is a remote risk for transmission of viral diseases.

Anaphylaxis

Anaphylaxis has been reported as a rare complication of interferon beta-1b use.

Necrosis

Injection-site necrosis may occur within the first 4 mo of therapy at single or multiple injection sites.

Suicide/Depression

Suicide attempts and depression may occur with increased frequency.

Patient Information

If patient or caregiver will be administering at home, review the Medication Guide with the patient or caregiver. Ensure that the patient or caregiver understands how to store, prepare, and administer dose, and how to dispose of used equipment and supplies. If possible, first injection should be performed under supervision of qualified health care provider.
Advise patient, family, or caregiver that medication is not a cure for multiple sclerosis, but it may decrease the number of flare-ups and slow the development of some of the physical disabilities caused by multiple sclerosis.
Advise patient not to change the dose or stop taking unless advised by health care provider.
Remind patient that injection is administered every other day.
Advise patient that if a dose is missed to take it as soon as possible and to schedule next dose approximately 48 h later.
Instruct patient to rotate injection sites as described in the Medication Guide to minimize likelihood of severe injection-site reactions or tissue necrosis.
Advise patient that flu-like symptoms are common and that acetaminophen can be used to relieve fever and muscle aches.
Advise patient to notify health care provider immediately if any of the following occur: drainage of fluid, injection-site reaction with break in skin and blue-black discoloration, severely depressed mood, suicidal ideation, swelling.
Advise patient to contact health care provider if experiencing bothersome adverse reactions or any unusual problems.
Advise women of childbearing potential to use effective contraception during treatment because of abortifacient potential.