An uncharacteristic level of hemoglobin concentration is one of the signs of anemia. In fact, this is not yet a diagnosis, but only a symptom that serves as a hallmark of many diseases. The progress of such a pathology may indicate a primary lesion of the blood system.
Erythropoiesis stimulator, known under the international non-proprietary name as "Epoetin alfa", is positioned by the instructions for use as a highly effective reagent, the pharmacological properties of which are aimed at the treatment and prevention of anemia of various etiologies. A well-chosen dosage not only helps to stabilize the component structure of the blood, but also positively affects the functioning of the heart muscle.
Product form and chemical composition
The medicinal product is supplied to pharmacies in the form:
- sterile pre-set dose disposable syringes (designed with extra needle protection);
- solution in vials.
The role of the auxiliary ingredient is assigned to:
- injectable water;
- chloride and sodium hydrogen phosphate dihydrate;
- polysorbate-80.
The biological activity of the substance in vials may be different. Most often, this is a thousand or two thousand international units for every 0.5 ml of liquid. However, there are other forms of the reagent on sale, including "Epoetin alfa" 10,000 units / 1 ml.
Mechanism of pharmacological action
The biological and immunological properties of the synthesized drug are absolutely identical to natural erythropoietin. Therefore, the drug very effectively inhibits the symptoms of anemia and corrects the composition of the blood as a typical glycoprotein. I must say that "Epoetin alfa" is primarily focused on increasing hematocrit and normalizing hemoglobin levels. Its "cardiac function", as well as the tendency of the components to improve blood flow in tissues, is less pronounced.
Half-life:
- with intravenous injection - four hours;
- with subcutaneous injection - about a day.
Maximum plasma concentration of reagent should be expected after 12-18 hours.
Pharmacokinetic nuances
In the course of research, it was found that the described drug induces the formation of antibodies in the "latent" mode, and its pharmacological significance in the processes of bone marrow fibrosis is close to zero. The protein fraction of the drug "Epoetin alfa" has about 165 amino acids (58% of the total molecular weight), and this finds itsreflection in the degree and quality of the influence of the components on the division/differentiation of progenitor cells.
Repeated intravenous administration (in the absence of renal pathologies) does not lead to accumulation of the active substance; in children under 12 years of age, prolongation of the T1 / 2 period to 6 hours is likely.
Indications for prescription
Epoetin alfa is recommended for use if:
- anemia diagnosed as a disorder of hematopoietic function that accompanies cancer (there are non-myeloid tumors);
- patient needs regular hemo- or peritoneal dialysis;
- there is a question about conducting a complex surgical operation using allogeneic blood transfusions;
- HIV-infected patient receiving zidovudine therapy;
- Effective prevention required.
Optimal dosing regimen
For the drug "Epoetin alfa" the formula for individual selection of the daily dose is valid. However, the general recommendations of the manufacturer are reduced to the following provisions and norms:
- at the start of the correction phase: fifty action units (AU) per kilogram of body weight, but no more than three injections/infusions per week;
- in the absence of visible changes: 75 U/kg at the same interval, but not earlier than one month after the start of treatment;
- in exceptional situations: 100-200 U/kg, strictly adhering to the indicated scheduleinjections (increment step - 25 units / month);
- maintenance therapy: the dose is prescribed so that the hematocrit is in the range of 30-35 vol. %.
As practice shows, the “standard” is most often taken as a one-time norm of 30-100 U / kg, which is usually taken at the end of the dialysis procedure. The optimal duration of an IV infusion is one to two minutes; with the subcutaneous mechanism for the delivery of the active substance, the same rules are followed.
Classification of likely side effects
About the scenarios of an atypical reaction of the body to the presence of the components of the drug "Epoetin alfa", the instructions for use report the following:
- Visualization of symptoms inherent in influenza viruses is possible - severe dizziness, depression, weakness, fever, acute joint/muscle pain;
- permissible imbalances in the work of the heart and blood lines - a sharp increase in blood pressure, malignant hypertension;
- cannot ignore the risk of thrombocytosis (this disease, although it makes itself felt extremely rarely, is fraught with serious complications);
- The reagent can influence the urinary system by changing the amount of potassium and phosphates in the body (an increase in plasma creatinine levels is not excluded).
On the skin, irritations are sometimes also noticeable, provoked by the introduction of the drug "Epoetin alfa". The instruction, in particular, speaks of rashes, eczema, angioedema. And what is interesting: with subcutaneous injections, the percentage of severity is much higher: per thousandthe average cases account for about 4 episodes (with IV infusions - only 1, 6).
There is no reliable information about the immune changes that would be caused by this substance (only the previously mentioned ability of the drug to induce the formation of antibodies deserves attention).
Contraindications declared by the manufacturer
Judging by the information provided in the official manual, "Epoetin alfa" (analogues such as "Binocrit" and "Eralfon" in this regard are as close as possible to the original) should not be used if:
- diagnosed with uncontrolled hypertension;
- the patient is hypersensitive to the ingredients;
- preliminary analysis showed the presence of a critical pathology of the blood lines;
- the patient suffered a heart attack (we are talking about the foreseeable past);
- there is reason to believe that normal blood circulation in the brain regions is disturbed.
In other words, the start of therapy should be preceded by a medical examination.
Special Instructions
"Epoetin alfa" (the trade name of a structurally identical drug may be different - for example, its analogues can be offered as a replacement: "Aeprin", "Repoetin-SP", "Epocomb", "Eprex", etc..) should be used with extreme caution in people suffering from intermittent/chronic peripheral muscle disorders. This rule is especially important if episodes have already been recorded in the anamnesis as a response of the body to the intake of certain drugs.convulsive reactions.
Vigilance and gout will not hurt. Emphasis should first be placed on issues related to blood pressure and the occurrence of headaches (antihypertensive drugs are one of the options for drug course adjustment). However, it is equally important to assess the true state of the iron depot (even before regular injections). When the implementation of adequate measures is not reflected in the blood pressure indicators, the reception of the described pharmacological product is stopped.
We must remember that kidney failure, oncology and HIV infection are included in the list of diseases, during which, against the background of an increase in hematocrit concentration, there is a characteristic decrease in the level of ferritin in the blood plasma. To level the disproportion, they resort to replacement therapy with the involvement of Fe-containing reagents.
It is advisable to take samples for hemoglobin 1 time every 7 days. Also, during the starting two months, regular monitoring of the number of platelets is required. And 5-10 days before surgery, substances with antithrombotic properties are injected into the patient's medical record.
The manufacturer does not exclude that the components of the drug can affect certain types of tumors, so monitoring the patient should not stop even after the end of the active phase of treatment.
What to do in case of an overdose?
"Epoetin alfa" (synonyms-drugs, by the way, behave in a similar way) with an overdose actsaccording to the algorithms embedded in the chemical formula of recombinant erythropoietin, that is, it provokes polycythemia and hematocrit fluctuations. Due to the lack of classic antidotes, no special measures are taken to deactivate the ingredients - the next medication is simply canceled.
Intentional phlebotomy is applicable in emergency cases, when an exorbitant hemoglobin indicator signals a real threat to life.
Interaction with medications
When conducting multi-stage complex therapy, it is extremely important to understand the principles of "pharmacological behavior" of the Epoetin alfa reagent (the release form, as mentioned above, may be different, but the mechanism of the biochemical reaction does not change from this).
So, in particular, parallel administration with blood products has a positive effect on the he alth dynamics. But we must remember that dilution of one solution with another is unacceptable. Medicinal "union" with cyclosporine is fraught with a decrease in the concentration of the latter (the optimal volume ratio of doses is determined empirically).
Reviews and comments
Analysis of the opinions expressed shows that the greatest number of questions arise when it comes to available options for solving the same problem. For example, few patients are aware of the differences that take place between such pharmacological products as Epoetin alfa and Epoetin beta.
What is the difference - it's easy to understand if you pay attention to the comments of doctors. The fact is that the structural model of natural erythropoietin is represented by two chains, and both have the desired effect on the blood system. Manufacturers of drugs, due to differences in technology, synthesize either the alpha fragment or the beta.
As for the reviews about the drug itself, many of those who had to try it on themselves testify that the remedy is quite effective, and in some special cases, completely indispensable for certain categories of patients.
