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Interferon Alfa-n3

Generic name: interferon alfa-n3 systemic

Brand names: Alferon N

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution, Injection:

Alferon N: 5,000,000 units/mL (1 mL)


Mechanism of Action

Interferons interact with cells through high affinity cell surface receptors. Following activation, multiple effects can be detected including induction of gene transcription. Inhibits cellular growth, alters the state of cellular differentiation, interferes with oncogene expression, alters cell surface antigen expression, increases phagocytic activity of macrophages, and augments cytotoxicity of lymphocytes for target cells

Use: Labeled Indications

Condylomata acuminata: Intralesional treatment of refractory or recurring external condylomata acuminata (venereal or genital warts) in patients 18 years of age or older.


Hypersensitivity to human interferon alpha proteins or any component of the formulation; anaphylactic sensitivity to mouse immunoglobulin (IgG), egg protein, or neomycin.

Dosage and Administration

Dosing: Adult

Condylomata acuminata: Intralesional: 250,000 units (0.05 mL) per wart twice weekly for a maximum of 8 weeks; maximum dose per treatment session: 2.5 million units (0.5 mL). Therapy should not be repeated for at least 3 months after the initial 8-week course of therapy (unless existing warts grow or new warts appear).

Dosing: Geriatric

Refer to adult dosing.


Inject into base of wart with a 30-gauge needle. For large warts, dose may be injected at several points around the outside edge of the wart (total dose: 0.05 mL/wart).


Store at 2°C to 8°C (36°F to 46°F); do not freeze or shake.

Drug Interactions

Aldesleukin: Interferons (Alfa) may enhance the adverse/toxic effect of Aldesleukin. In particular, risks of myocardial and renal toxicity may be increased by this combination. Consider therapy modification

BCG (Intravesical): Myelosuppressive Agents may diminish the therapeutic effect of BCG (Intravesical). Avoid combination

Chloramphenicol (Ophthalmic): May enhance the adverse/toxic effect of Myelosuppressive Agents. Monitor therapy

Cladribine: May enhance the myelosuppressive effect of Myelosuppressive Agents. Avoid combination

CloZAPine: Myelosuppressive Agents may enhance the adverse/toxic effect of CloZAPine. Specifically, the risk for neutropenia may be increased. Monitor therapy

Deferiprone: Myelosuppressive Agents may enhance the neutropenic effect of Deferiprone. Management: Avoid the concomitant use of deferiprone and myelosuppressive agents whenever possible. If this combination cannot be avoided, monitor the absolute neutrophil count more closely. Consider therapy modification

Dipyrone: May enhance the adverse/toxic effect of Myelosuppressive Agents. Specifically, the risk for agranulocytosis and pancytopenia may be increased Avoid combination

Mesalamine: May enhance the myelosuppressive effect of Myelosuppressive Agents. Monitor therapy

Methadone: Interferons (Alfa) may increase the serum concentration of Methadone. Monitor therapy

Promazine: May enhance the myelosuppressive effect of Myelosuppressive Agents. Monitor therapy

Ribavirin (Oral Inhalation): Interferons (Alfa) may enhance the adverse/toxic effect of Ribavirin (Oral Inhalation). Hemolytic anemia has been observed. Monitor therapy

Ribavirin (Systemic): Interferons (Alfa) may enhance the adverse/toxic effect of Ribavirin (Systemic). Hemolytic anemia has been observed. Monitor therapy

Vitamin K Antagonists (eg, warfarin): Interferons (Alfa) may enhance the anticoagulant effect of Vitamin K Antagonists. Monitor therapy

Zidovudine: Interferons may enhance the adverse/toxic effect of Zidovudine. Interferons may decrease the metabolism of Zidovudine. Monitor therapy

Adverse Reactions

Adverse reaction incidence noted below is specific to intralesional administration in patients with condylomata acuminata.


Central nervous system: Headache (31%), chills (14%), fatigue (14%)

Hematologic & oncologic: Decreased white blood cell count (11%)

Neuromuscular & skeletal: Myalgia (45%)

Respiratory: Flu-like symptoms (30%; includes headache, fever, and/or myalgia; abated with repeated dosing)

Miscellaneous: Fever (40%)

1% to 10%:

Central nervous system: Malaise (9%), dizziness (9%), depression (2%), insomnia (2%), vasodepressor syncope (2%), hyperesthesia (tongue: 1%), paresthesia (1%)

Dermatologic: Diaphoresis (2%), pruritus (2%)

Endocrine & metabolic: Increased thirst (1%)

Gastrointestinal: Nausea (4%), vomiting (3%), dyspepsia (3%), diarrhea (2%), dysgeusia (1%)

Hematologic & oncologic: Adenopathy (groin: 1%)

Neuromuscular & skeletal: Arthralgia (5%), back pain (4%), muscle cramps (1%)

Ophthalmic: Visual disturbance (1%)

Respiratory: Rhinitis (2%), epistaxis (1%), pharyngitis (1%)

<1%, postmarketing, and/or case reports: Dysuria, hepatotoxicity (idiosyncratic; Chalasani 2014), hot flash, lack of concentration, nervousness, skin photosensitivity


Concerns related to adverse effects:

  • Flu-like symptoms: Flu-like symptoms are common; may aggravate debilitating conditions.
  • Hypersensitivity reactions: Discontinue use if signs/symptoms of hypersensitivity reactions occur (eg, urticaria, angioedema, bronchoconstriction, anaphylaxis).

Disease-related concerns:

  • Bone marrow suppression: Use with caution in patients with severe myelosuppression.
  • Cardiovascular disease: Use with caution in patients with preexisting cardiovascular disease (eg, unstable angina, uncontrolled CHF). In a scientific statement from the American Heart Association, interferon has been determined to be an agent that may either cause reversible direct myocardial toxicity or exacerbate underlying myocardial dysfunction (magnitude: moderate/major) (AHA [Page 2016]).
  • Coagulation disorders: Use with caution in patients with coagulation disorders (eg, thrombophlebitis, pulmonary embolism, hemophilia).
  • Diabetes: Use with caution in patients with diabetes with ketoacidosis.
  • Pulmonary disease: Use with caution in patients with severe pulmonary disease (eg, chronic obstructive pulmonary disease).
  • Seizure disorder: Use with caution in patients with seizure disorders.

Dosage form specific issues:

  • Albumin: Contains albumin, which may carry a remote risk of transmitting Creutzfeldt-Jakob or other viral diseases.
  • Product variability: Due to differences in manufacturing, strength, and type of interferon, do not change from one brand of interferon to another; a change in dosage may be required.

Other warnings/precautions:

  • Appropriate use: Patients should be selected for therapy based on a number of factors: the locations and sizes of the lesions, past treatment and response, and the patient's ability to comply with the treatment regimen. Therapy is particularly useful for patients who have not responded satisfactorily to other treatment modalities (eg, podophyllin resin, surgery, laser or cryotherapy).


Pregnancy Risk Factor


Pregnancy Considerations

Animal reproduction studies have not been conducted. Menstrual irregularities have been reported; effective contraception is recommended during treatment.

Patient Education

  • Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
  • Patient may experience joint pain, muscle pain, loss of strength and energy, back pain, trouble sleeping, fatigue, injection site irritation, nausea, vomiting, diarrhea, mouth irritation, mouth sores, or flu-like symptoms. Have patient report immediately to prescriber signs of infection, severe dizziness, passing out, chest pain, or blurred vision (HCAHPS).
  • Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

Source: Wolters Kluwer Health. Last updated November 18, 2019.