The most common side effect of interferons is the flu-like syndrome. It manifests itself in the form of weakness, a sense of fatigue, muscle aches, fever, chills, headache, nausea, sweating. These symptoms are usually more pronounced at the beginning of the treatment, the frequency and intensity decrease as the treatment continues.
In any period of treatment, neurologic symptoms similar to exacerbation of multiple sclerosis may occur: transient episodes of muscle hypertonicity and / or muscle weakness that limit the possibility of voluntary movements. These episodes, limited in duration, are associated with time injections and may be repeated with subsequent administrations. In some cases, these symptoms are accompanied by influenza-like symptoms.
In each particular category, side effects are grouped according to the system-organ class and are presented in descending order of frequency:
Often (> 1/10 patient-years *)
Often (from 1/100 to 1/10 patient-years)
Infrequently (from 1/1000 to 1/100 patient-years)
Rarely (from 1/10 000 to 1/1 000 patient-years)
Rarely (<1/10 000 patient-years)
Unknown (based on the available data, the assessment is not possible)
* patient-years is the sum of the individual units of time during which the patient who participated in the study received Avonex before developing an adverse reaction.
Laboratory and instrumental studies:
Often: lymphocytopenia, leukopenia, neutropenia, decreased hematocrit, an increase in potassium in the blood, an increase in the content of nitrogen, urea blood.
Infrequently: decrease in the number of platelets compared with baseline.
Unknown: decrease in body weight, increase in body weight, deviation of the parameters of the functional test of the liver from normal.
Heart Disease:
Unknown: Cardiomyopathy, congestive heart failure, palpitation, arrhythmia, tachycardia.
Disturbances from the hemopoietic system and lymphatic system:
Unknown: pancytopenia, thrombocytopenia.
Impaired nervous system:
Often: headache2.
Often: muscle spasms, hypoesthesia
Unknown: neurologic symptoms, fainting3, hypertension, dizziness, paresthesia, convulsions, migraine.
Disturbances from the respiratory organs:
Often: rhinorrhea.
Rarely: dyspnea.
Gastrointestinal disorders:
Often: vomiting, diarrhea, nausea2.
Disturbances from the skin, its appendages and subcutaneous tissue:
Often: rash, intense sweating, bruises.
Infrequently: alopecia.
Unknown: angioedema, itching, vesicular rash, hives, exacerbation of psoriasis.
Disturbances from the musculoskeletal and connective tissue:
Often: Muscular spasms, neck pain, myalgia2, arthralgia, pain in the extremities, back pain, muscle stiffness, musculoskeletal rigidity.
Unknown: systemic lupus erythematosus, muscle weakness, arthritis.
Endocrine disorders:
Unknown: hyperthyroidism, hypothyroidism.
Metabolic and nutritional disorders:
Often: anorexia.
Infectious and parasitic diseases:
Unknown: abscess at injection site1.
Vascular disorders:
Often: tides blood to the face.
Unknown: vasodilation
Systemic disorders and conditions at the injection site:
Often: influenza-like symptoms2, chills2, sweating2.
Often: pain at the injection site, erythema at the injection site, hematoma in place injections, asthenia2, pain, fatigue2, malaise, night sweats.
Infrequently: burning at the injection site.
Unknown: reaction at the injection site, inflammation at the injection site, cellulite at the injection site1, necrosis at the injection site, bleeding at the injection site, chest pain.
Immune system disorders:
Unknown: Anaphylactic shock, anaphylactic reaction, hypersensitivity reaction (angioedema, dyspnea, urticaria, rash, itching rash)
Hepatobiliary disorders:
Unknown: hepatic failure, hepatitis, autoimmune hepatitis.
Disorders from the reproductive system and breast:
Infrequently: metrorrhagia, menorrhagia.
Mental disorders:
Often: depression, insomnia.
Unknown: suicide, psychosis, anxiety, confusion, emotional lability.
- The described reactions at the injection site include pain, inflammation and very rare cases of abscess or cellulitis that may require surgery.
- The frequency of these effects is higher at the beginning of treatment.
- After Avonex's injection, a syncope is possible, as a rule, such fainting turns out to be the only episode at the beginning of treatment and is not repeated with subsequent injections.
Precautionary measures:
Before starting treatment, patients should be informed of possible side effects associated with the use of the drug. In view of the possibility of spontaneous abortion on the background, the use of interferons beta, women with preserved reproductive capacity should be. recommend the use of effective methods of contraception. Avonex®, like other interferons, should be used with caution in the treatment of patients with depression or depressive disorders. It is known that when interferons are used, depression and suicidal thoughts may occur, and in a group of people suffering from PC, the frequency of such phenomena increases. The emergence of depressive states is possible at any time of treatment with Avonex. If there are any signs of depression or suicidal thoughts, patients should immediately consult a doctor. For such patients, it is necessary to establish close monitoring during treatment and, if necessary, to urgently apply appropriate medical measures. In some cases, it may be necessary to stop the use of the drug.
Care must be taken in appointing Avonex to patients who previously suffered seizures, and also taking antiepileptic drugs, in particular if adequate control over the seizures can not be achieved. If epileptic seizures occur in patients who have not previously suffered from epilepsy, the etiology of seizures should be established and an appropriate anticonvulsant therapy should be instituted before the use of Avonex® can be resumed.
Care should be taken in the appointment, as well as carefully monitor patients suffering from severe renal and hepatic impairment, as well as with oppression of bone marrow hematopoiesis.With the use of interferon beta, the appearance of signs of impaired liver function, such as an increase in the level of liver enzymes in the serum, the development of hepatitis, including autoimmune, liver failure. However, it is not known whether this is a consequence of taking interferon beta-1a or is associated with taking other medications that are usually prescribed to such patients. Patients should be closely monitored for signs of liver function disorder, especially if interferon is used, in conjunction with other hepatotoxic drugs.
When using Avonex®, the condition of patients with cardiovascular diseases should be closely monitored: angina pectoris, myocardial infarction, heart failure, arrhythmia, as the manifestations of influenza-like syndrome caused by the use of the drug may have a stressful effect on them.
When using interferons, there may be deviations in laboratory indicators, so in addition to the usual laboratory tests conducted by patients PC, in the course of treatment, it is recommended to count blood cells (including platelets), to determine the leukocyte formula, and a biochemical blood test (including liver enzymes). Those patients who have signs of oppression of bone marrow hematopoiesis may need a detailed study of the blood formula with the calculation of the number of platelets.
When Avonex® is used for one year in serum, 8% of patients develop interferon-neutralizing antibodies that can decrease the activity of interferon beta-1α, and, consequently, the clinical efficacy of the drug.