Capecitabine (lat. Capecitabinum) is a substance that is a derivative of fluoropyrimidine carbamate. It belongs to the group of antimetabolites - special compounds that can inhibit the growth of malignant tumors. Interest in such substances arose in 1960. At first, positive data were obtained through studies on laboratory mice. Some time later, their effectiveness in the treatment of certain human cancers was discovered.
Today, many anticancer drugs contain capecitabine as an active ingredient. Feedback from many patients speaks of the success of the use of such drugs in anticancer therapy.
Pharmacological group and properties
The formula of capecitabine is 5'-deoxy-5-fluoro-N-[(pentyloxy)carbonyl]cytidine. The chemical group of antimetabolites is represented by a number of substances that are close in nature to the products of human metabolism (metabolism). They are able to enter into metabolic reactions, correct them and inhibit some biochemical processes. In this case, there is a violation of the normal vital activity of tumor cells and inhibition of their growth when using drugs based on the substance capecitabine. Reviews of people speak of a decrease in the size of neoplasms. This mechanism of action is called cytostatic.
Such properties of antimetabolite substances make it possible to use them in antitumor therapy. Their effectiveness in relation to malignant neoplasms of the gastrointestinal tract and mammary glands has been proven. At the same time, both monotherapy and combination with other means give a good result. To date, more than 800 drugs have been created based on antimetabolites, but the search for new groups of compounds is still ongoing.
Mechanism of action
Activation of capecitabine occurs in the tissues of the tumor itself, after which it begins to have a toxic effect on its cells (cytotoxic mechanism). This substance is involved in metabolic reactions and leads to the fact that both he althy and tumor cells will be converted into cytotoxic analogues. In this case, there is a violation of the production of a substance necessary for DNA synthesis and, accordingly, the division process.
This is how cells stop growing. According to another scenario, there is a "substitution" of one substance for another, as a result of which protein synthesis is disrupted when taking drugs based on the compound capecitabine. The manual describes this process in detail.
The mechanism of this transformation minimizes the possibility of damage to he althycells. Capecitabine is more concentrated in the tumor itself than in surrounding tissues. This feature harms the body less when a person is being treated with a drug based on the substance capecitabine. Instructions for use recommend taking the drug in strictly prescribed doses, which are determined by the attending physician.
Residence of a substance in the body
After taking capecitabine, it is rapidly absorbed in the gastrointestinal tract. If you eat at this time, the process will slow down. Therefore, the administration of drugs based on antimetabolites is carried out after a meal. Further transformations of the substance occur in the liver, a certain amount of capecitabine and its metabolites binds to proteins (for example, blood albumin). Peak plasma levels are reached 1.5-3 hours after drug administration. This is indicated by the instruction for the drug "Capecitabine". Analogues have similar pharmacokinetics.
Most of the substance is excreted in the urine, less - in the faeces. Moreover, the body leaves not only capecitabine unchanged (about 3%), but also its derivatives. Some of them are metabolized to less active compounds. The presence and transformation of capecitabine in the body is not affected by gender, age, race.
When appointed?
Capecitabine in the form of various drugs is prescribed to patients with breast cancer, including those at the stage of metastasis. In this case, the substance is used as part of monotherapy, or combined treatment in the presence of contraindications or ineffectiveness.chemotherapy. Most often, capecitabine is combined with docetaxel.
Also prescribed for patients with cancer of the colon, esophagus, stomach, pancreas, colorectal cancer, both in the stage of local spread and during metastasis. In the treatment of colon cancer, "Capecitabine" is also prescribed. Instructions for use recommends that you carefully follow the dosage and follow the advice of your doctor.
Interaction with other tools
If chemotherapy courses are ineffective, an oncologist can prescribe a combination treatment that will involve "Capecitabine". Instructions for use provides a list of funds with which a successful combination is possible.
For example, with "Docetaxel" - a drug of a cytotoxic type of action, of plant origin. It is able to remain in cells for a long time at high concentrations. However, this combination of agents is contraindicated in people with platelet and neutrophil counts of 100,000/µl and 1500/µl, respectively. Also, "Docetaxel" is not used for patients with an increased rate of bilirubin. In this case, unpleasant consequences are possible. If "Docetaxel" for some reason "falls out" of the treatment regimen, continue therapy with "Capecitabine", but in reduced doses.
If a hypersensitivity reaction occurs, treatment with "Capecitabine" and "Docetaxel" is stopped and the symptoms are eliminated. Combined schemedrug intake is developed by a competent oncologist. If toxic effects occur, this scheme is adjusted.
"Capecitabine" is not prescribed simultaneously with "Sorivudine" - an antiviral agent. This combination may increase the toxicity of the first drug. Combined use with the antiepileptic drug "Phenytoin" increases the concentration of the latter in the blood plasma. It is also possible a violation of blood clotting when using coumarin anticoagulants and drugs, where the main component is capecitabine. The instructions for use warn of possible consequences, so you must first read it.
Who is contraindicated for?
Reasons for contraindicated or restricted use of the drug may be:
- High sensitivity (hypersensitivity reaction).
- Severe renal and hepatic failure.
- Various stages of pregnancy (the drug affects the fetus), except when the life of the mother is a priority;
- Breastfeeding a newborn.
Also, the use of capecitabine is limited for people with coronary heart disease (CHD), with a state of increased concentration of bilirubin in the blood, liver damage with metastases with a violation of its basic functions. For minor children and the elderly, the drug is not recommended. This confirms the instructions for the drug "Capecitabine". Patient reviews speak of many side effects and toxic manifestations withtreatment. Therefore, capecitabine therapy is carried out under the strict supervision of a specialist oncologist.
Are there any side effects?
After taking the drug, a headache, a state of rapid fatigue, apathy, and weakness are possible. Insomnia may occur, or, conversely, drowsiness. In rare cases - impaired coordination and balance, confusion.
A side effect on the cardiovascular system is anemia (anemia). To a lesser extent, angina pectoris, myocardial ischemia, heart attack, heart failure, and others are possible. If the respiratory organs are involved in the process, shortness of breath, a feeling of sore throat, cough may appear. Very rare - pulmonary embolism, pulmonary spasm.
When used as part of monotherapy or combined treatment, a negative effect on the musculoskeletal system is possible. It manifests itself in pain in the limbs and lower back, the occurrence of muscle hypertonicity (myalgia), joint pain (arthralgia).
Skin can also suffer. Perhaps the appearance of dermatitis, erythema, excessive dryness of the skin, redness, tingling, numbness, peeling, itching, increased pigmentation, the lesion also affects the nails. In rare cases, skin cracks, increased sensitivity to ultraviolet radiation, peeling and increased fragility of the nail plates occur.
Among other side effects, infectious processes may occur against the background of a decrease in the body's defenses. After all, drug therapy causes a decrease in blood platelets and leukocytes. Suchmanifestations are described for the drug "Capecitabine" instructions for use. Analogues give the same effects.
Taking the drug
"Capecitabine" is suitable for internal use only. Usually it is washed down with water half an hour after eating, but not later.
The daily dose is determined by the attending oncologist, depending on the size of the neoplasm, stage of development and total body surface area. It is desirable that the specialist already had the skills to work with this drug. Most often, a double dose is prescribed - morning and evening. In this case, the entire course lasts for two weeks, then a break for seven days, followed by a repeat of the treatment.
For patients with renal insufficiency, daily doses are reduced. With a decrease in the number of leukocytes (leukopenia) and neutrophilic granulocytes (neutropenia) in the blood, the drug is continued. So recommends the instructions for use to the "Capecitabine" remedy. Synonyms or analogues are prescribed at the initiative of the attending physician.
Toxicity levels
There are several degrees, according to which the toxic effect of the drug "Capecitabine" develops (instructions for use). Feedback from many people suggests that this process is purely individual.
There are several degrees of toxicity:
- 1 degree. Minor side effects appear.
- 2 degree. Intensive diarrhea (up to 4 times a day) accompanied by swelling of the extremities, redness, impaired activity,a sharp increase in bilirubin. At this stage, capecitabine is discontinued until signs of stage 1 toxicity appear.
- 3 degree. Diarrhea increases up to 9 times a day. Malabsorption occurs (malabsorption syndrome). In this case, strong peeling of the skin, redness, the appearance of ulcers and blisters are observed. There are sharp pains in the limbs, decreased performance. Bilirubin rises 3 times. At this stage, treatment is interrupted, and with the manifestation of 1 degree of toxicity, the drug is continued at a reduced dose.
- 4 degree. More frequent diarrhea - up to 10 times per day. Fecal masses with an admixture of blood. There is a need for the introduction of drugs, bypassing the gastrointestinal tract. If signs of this degree appear, treatment is stopped and no longer resumed.
What precautions should I take?
The course of treatment should take place under close medical supervision. The specialist must identify toxic manifestations in time - whether it be nausea, diarrhea, etc. If these signs are detected, the treatment is adjusted. If necessary, eliminate the symptoms, reduce the daily dose, take a break. Continue treatment if signs of toxicity are not life-threatening.
For people with coronary heart disease, specialist supervision should be especially thorough. In this case, it is necessary to identify the negative impact on the cardiovascular system in time and take the necessary measures in time.
Specialists refrain from using the substance in pediatric practice. The effectiveness of its use in children has not been established. If aa woman of childbearing age is being treated, she should be warned about the effect of capecitabine on the fetus. She should use reliable contraceptives while on therapy.
Preparations and analogues
There are several capecitabine-based products. There are 7 trade names of drugs produced by several domestic and foreign companies on the Russian market. For example:
- "Capecitabine".
- "Capecitabine-TL".
- "Tutabin".
- "Xeloda".
- "Kabetsin".
- "Capecitover".
- "Capametin FS".
Since all these drugs are based on the same active ingredient - capecitabine, the instructions for them will be similar. Usually, it contains a table for calculating the dosage taking into account body weight and a treatment correction scheme for signs of toxicity of varying degrees.
It is important to understand that the first thing you should be familiar with when, for example, "Capecitabine TL" was prescribed is an instruction. The information given in it is not suitable for independent use of funds! All calculations related to setting the dose and treatment regimen are made by the attending physician - an oncologist, who has sufficient competence in this matter. Self-administration of anticancer drugs causes irreparable harm to the body.
Let's take a closer look at some of the drugs.
Drug descriptions
- "Capecitabine - TL" is produced by the Russian company LLC "Technology of Medicines". The key ingredient is capecitabine. Instructions for use, release form are of interest to many. Let's consider in more detail. These are film-coated tablets. The content of the active substance is 150 or 500 mg. Auxiliary components: cellulose, lactose, croscarmellose sodium, hypromellose, magnesium stearate. One package may contain 60 or 120 tablets, depending on the dosage of the drug "Capecitabine - TL". The instruction necessarily contains detailed information on the use of the product.
- "Capecitabine" is a domestic drug with the same active ingredient. Its description is similar to the tool above. The release form of the drug "Capecitabine" - tablets. Instructions for use are also included in the package.
- "Kabetsin" is a Russian-made antitumor drug (Company Deco LLC). Release form - film-coated tablets of 150 or 500 mg of active ingredient. Minor components: microcrystalline cellulose, crospovidone, starch, magnesium stearate. Dispensing from pharmacies by prescription only.
- "Capecitover" is a product of the Russian company JSC "Veropharm". This anticancer drug is available in tablets of 150 or 500 mg in the amount of 60 - 120 pieces. In addition to capecitabine, the composition of the drug includes lactose, cellulose, croscarmellose sodium, sodium stearate and hypromellose.
- "Kapametin FS" - produced by the Russian company "Nativa" - an active participant in the programimport substitution of medicines. "Capametin FS" is produced with a dosage of 150 - 500 mg, the active substance is capecitabine. Instructions for use (the manufacturer is also indicated in it) will tell you how many tablets are in the package - 60 or 120.
- "Tutabine" is a foreign drug based on capecitabine. It is produced by the Argentine company Laboratorio VARIFARMA S. A., which is also the registrar of the product. "Tutabin" is produced in the form of tablets with an active ingredient content of 500 mg. Packaging - cardboard box with attached instructions.
- Xeloda is an anticancer drug. Produced in Switzerland by the firm "F. Hoffman La Roche", as well as its subsidiaries and representative offices in other countries - Mexico and the United States. There are 5 drugs with this trade name on the Russian market. Release form - tablets (150 - 500 mg) of 60 or 120 pcs. in one package.
Reviews
Reviews on the work of drugs based on capecitabine are very different. Most of them are positive, but there are also negative reviews. However, this does not characterize these funds as good or bad, because the factor of the individuality of the organism of each individual person should always be taken into account. Taking the same remedy by different people never gives the same result. Of great importance is which particular organ was affected by the neoplasm and how long this has been happening.
People who took the drug talk aboutstrong toxic effect after several days of use. However, many note a significant improvement in their condition and even entry into a period of remission. An important condition for the drug to work as well as possible for an individual person is the consultation of an oncologist and strict adherence to his instructions regarding treatment.
