CHEMOTHERAPY DRUGS ACTING AGAINST BREAST CANCER

Chemotherapy (sometimes cancer chemotherapy) is the treatment of cancer with anantineoplastic drug or with a combination of such drugs into a standardized treatment regimen.

Most commonly, chemotherapy acts by killing cells that divide rapidly, one of the main properties of most cancer cells. This means that it also harms cells that divide rapidly under normal circumstances: cells in the bone marrow, digestive tract and hair follicles; this results in the most common side effects of chemotherapy: myelosuppression (decreased production of blood cells, hence also immunosuppression), mucositis (inflammation of the lining of the digestive tract), and alopecia (hair loss).

Breast cancer (malignant breast neoplasm) is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas.


CHEMOTHERAPY DRUGS:

• Tamoxifen
• Paclitaxel
• Docetaxel
• Doxorubicin
• Cyclophosphamide
• Methotrexate
• 5-Fluorouracil
• Vinca Alkaloids- Vincristine & Vinblastine
• Gemcitabine
• Epirubicin

TAMOXIFEN

Tamoxifen has been used since many years to treat breast cancer in women and men.

It is majorly used to treat patients with early-stage breast cancer, as well as those with metastatic breast cancer.

As adjuvant therapy , it helps to prevent the original breast cancer from returning and also helps to prevent the development of new cancers in the other breast. As treatment for metastatic breast cancer, the drug slows or stops the growth of cancer cells that are present in the body.

Estrogen can promote the growth of breast cancer cells. Some breast cancers are classified as estrogen receptor-positive, which means that they have a protein to which estrogen will bind. These breast cancer cells need estrogen to grow. Tamoxifen works against the effects of estrogen on these cells.

Mechanism of Action:

Tamoxifen competitively binds to estrogen receptors on tumors and other tissue targets, producing a nuclear complex that decreases DNA synthesis and inhibits estrogen effects. It is a Nonsteroidal agent with potent Antiestrogenic properties which compete with estrogen for binding sites in breast and other tissues. Tamoxifen causes cells to remain in the G0 and G1 phases of the cell cycle. Because it prevents (pre)cancerous cells from dividing but does not cause cell death, Tamoxifen is Cytostatic rather than cytocidal.

Common Side Effects:

The known, serious side effects of Tamoxifen are blood clots, strokes, uterine cancer, and cataracts.

Other side effects of Tamoxifen are similar to the symptoms of menopause. The most common side effects are hot flashes and vaginal discharge.

Some women experience irregular menstrual periods, headaches, fatigue, nausea and/or vomiting, vaginal dryness or itching, irritation of the skin around the vagina, and skin rash. As with menopause, not all women who take Tamoxifen have these symptoms.

Men who take Tamoxifen may experience headaches, nausea and/or vomiting, skin rash, impotence, or decreased sexual interest.

Dose: 10-20 mg twice daily.

Presentation:Tamoxifen Tablets - 10mg and 20 mg

PACLITAXEL:

Paclitaxel is a complex diterpin taxane obtained from bark of Western yew tree, which exerts cytotoxic action by a novel mechanism.

Mechanism Of Action:

Paclitaxel is called a mitotic inhibitor. Cells grow by a process called mitosis (cell division). Paclitaxel targets rapidly growing cancer cells, sticks to them while they are trying to divide, and prevents them from completing the division process. Since the cancer cells cannot divide into new cells, it can't grow and metastasize.

Adverse Effects:

• Myelosuppression
• Chest pain
• Arthralgia
• Myolgia
• Edema
• Mucositis

Dose:175mg/m2 by i.v. infusion over 3 hrs, repeated every 3 weeks.

Presentation:Paclitaxel Injection - 3mg/5ml, 100mg/16.7ml and 260mg/43.4ml.

DOCETAXEL:

Docetaxel is the more potent congener of paclitaxel. 

Mechanism Of Action:

Docetaxel is called a mitotic inhibitor. Cells grow by a process called mitosis (cell division). Paclitaxel targets rapidly growing cancer cells, sticks to them while they are trying to divide, and prevents them from completing the division process. Since the cancer cells cannot divide into new cells, it can't grow and metastasize. 

Adverse Effects:

• Major toxicity is neutropenia, but neutropenia is less frequent.
• Arrhythmias,
• Fall in BP
• Heart failure

Dose:100 mg/m2 i.v. over 1 hr; repeat at 3 weeks. 

Presentation:Docetaxel Injection - 40mg/ml

DOXORUBICIN:

Doxorubicin is a chemotherapy drug, a type of anthracycline antibiotic that is an anti-tumor drug. It is made from the bacterium Streptomyces.

Doxorubicin can be used to treat early-stage or node-positive breast cancer, HER2-positive breast cancer, and metastatic disease. Doxorubicin is sometimes combined with Cyclophosphamide and/or 5-fluorouracil to make a cocktail of breast-cancer fighting chemotherapy drugs. 

Mechanism Of Action:

Doxorubicin fights cancer by slowing or stopping the growth of cancer cells. This drug gets inside the DNA of cancer cells and prevents cell replication by inhibiting protein synthesis. 

Adverse Effects:

• Allergic reaction to Doxorubicin
• May harm foetus in pregnant women
• Possible future infertility
• greater danger of infections
• In some cases, there is a risk of heart damage

Dose:60-75 mg/m2 BSA slow i.v. injection every 3 weeks.

Presentation:Doxorubicin Hydrochloride Injection - 10mg/ml and 50mg/25ml.

CYCLOPHOSPHAMIDE:

Cyclophosphamide is an anticancer drug that can be given either intravenously or orally in tablet form. The intravenous drug is clear.


This drug is most often given with doxorubicin.
Four to six cycles of treatment over three to six months are commonly administered for breast cancer.
Chloramphenicol retards the metabolism of Cyclophosphamide. 

Mechanism Of Action:

The main effect of cyclophosphamide is due to its metabolite phosphoramide mustard.

Phosphoramide mustard forms DNA crosslinks between (interstrand crosslinkages) and within (intrastrand crosslinkages) DNA strands at guanine N-7 positions. This leads to cell death.

Adverse Effects:

Cyclophosphamide can cause irritation of the lining of the urinary bladder and often nausea and vomiting. 

Dose:2-3 mg/kg/day oral; 10-15mg/kg i.v.

Presentation:

• Cyclophosphamide Tablets- 50mg
• Cyclophosphamide Injection- 200mg/15ml, 500mg/30ml and 1gm/50ml.

METHOTREXATE: 

Methotrexate is an anticancer drug that is usually given intravenously for women with breast cancer. 

This drug is most often given with both cyclophosphamide and 5-fluorouracil. Four to six cycles of the treatment over three to six months are commonly given for breast cancer.

Mechanism Of Action:

Methotrexate has cell cycle specific action- kills cells in S phase; primarily inhibits DNA synthesis, but also affects RNA and protein synthesis.

Phosphoramide mustard forms DNA crosslinks between (interstrand crosslinkages) and within (intrastrand crosslinkages) DNA strands at guanine N-7 positions. This leads to cell death.

Adverse Effects:

• It exerts major toxicity on bone marrow-low doses given repeatedly cause megaloblastic anemia, but high doses produce pancytopenia.
• Desquamation and bleeding may occur in g.i.t.
• Some women who receive methotrexate experience mouth sores following treatment.

Dose:

15-30 mg /day for 5 days orally, or 20-40 mg/m2 body surface area i.m. or i.v. twice weekly. 

Presentation:

Methotrexate Tablets- 2.5mg

Methotrexate Injection- 25mg/ml

5-FLUOROURACIL: 

5-Fluorouracil is an anticancer drug that is given intravenously. It is pyrimidine analog. It belongs to the class of drug, Antimetabolites.

This drug is most often given with both cyclophosphamide and methotrexate.

This drug combination is referred to as "CMF".

Mechanism Of Action:

It is converted in the body to the corresponding nucleotide 5-fluoro-2-deoxyuridine monophosphate, which inhibits thymidilate synthetase and blocks the conversion of dexoyuridilic acid to deoxythymidylic acid. Thus DNA cannot be synthesized.

Adverse Effects:

• Myelosuppression
• Mucositis
• Dermatitis
• Diarrhea
• Cardiac toxicity.
• For some women, 5-fluorouracil can cause mouth sores and diarrhea.

Dose: 1 g orally on alternate days (6 doses) then 1 g weekly, or, 12mg/kg/day i.v. for 4 days than 6mg/kg i.v. on alternate days. 

Presentation:Fluorouracil Injection- 50mg/ml

VINCA ALKALOIDS:

Vinblastine and Vinblastine are vinca alkaloids. Both are mitotic inhibitor, and are used in cancer chemotherapy. 

Mechanism Of Action:

Both binds to the Microtubular protein-tubulin, prevent its polymerisation and assembly of microtubules, cause disruption of mitotic spindle and interfere with cytoskeletol function. The chromosomes fail to move apart during mitoisis: metaphase arrest occurs. Vinca alkaloids are cell cycle specific and act in the mitotic phase. 

Adverse Effects:

The degree and severity of the side effects depend on the amount and schedule of the administration of the drug. Following are some of the most common and important ill effects:

• Low platelet count
• Anemia
• Hair loss
• Bowel paralysis
• Diarrhea
• Nerve Damage
• Damage to veins
• Extravasation

Dose:

Vinblastine--0.1-0.15 mg/kg i.v. weekly * 3 doses.

Vincristine-1.5-2mg/m2 body surface area i.v. weekly. 

Presentation:

Vinblastine Sulphate Injection- 1mg/ml

Vincristine Sulphate Injection -1mg/ml 

GEMCITABINE:

Gemcitabine is a member of a general group of chemotherapy drugs known as antimetabolites. It is used in breast cancer. 

Mechanism Of Action:

It prevents cells from making DNA and RNA by interfering with the making of nucleic acids, which stops cell replication, causing the cells to die. 

Adverse Effects:

• decreased white blood cell count with increased risk of infection
• decreased platelet count with increased risk of bleeding
• nausea
• vomiting
• loss of appetite
• fatigue
• abnormal blood tests which suggest that the drug is affecting the liver

Dose:

Gemcitabine is administered by the IV route, since it is extensively metabolized by the gastrointestinal tract. Dose ranges from 1-1.2 g/m2 according to type of cancer treated. 

Presentation:

Gemcitabine Hydrochloride Injection- 200mg and 1gm 

EPIRUBICIN: 

Epirubicin is a chemotherapeutic drug that is used for the treatment of breast cancer that has spread to the lymph nodes following breast cancer therapy. 

Mechanism Of Action:

Epirubicin prevents cells from replicating and kills them. It forms complexes between the base pairs of DNA in both healthy and cancerous cells. Interaction with healthy cells is responsible for all the side effects associated with the use of epirubicin. The disruption of DNA prevents the cell from replicating and producing proteins. 

Adverse Effects:

The following are some common side effects associated with the use of epirubicin:

• Reddish urine (for 1-2 days)
• Nausea
• Vomiting
• Mouth sores
• Dehydration
• Diarrhea
• Signs of congestive heart failure (e.g., shortness of breath, ankle swelling)
• Fever
• Signs of infection
• Pain, burning or stinging at the injection site
• Reversible alopecia (hair loss)
• Low blood cell counts (anemia, leukopenia, neutropenia and thrombocytopenia)
• Fatigue
• Temporary or permanent loss of menstrual cycle in women
• Hot flashes
• Rash/itch

Epirubicin may cause an inflammation reaction (swelling, tenderness, or redness) at the site of treatment with radiation. 

Dose:

Typically, epirubicin is given intravenously over 15-20 minutes at a starting dose of 100-120 mg/m2 (square meter of body surface area). 

Lower doses, such as 75-90 mg/m2, may be used in patients who may not tolerate the regular dose. Epirubicin is given in repeated three- or four-week cycles.

The dose can be given either on day one of the cycle or split into two doses given on day one and day eight of the cycle. Dosage can be adjusted based on the response.

Presentation:

Epirubicin Hydrochloride Injection- 10mg and 50mg