Paclitaxel - Indications, Dosage, Precautions, and Side Effects

What Is Paclitaxel?

Paclitaxel is a chemotherapy medicine that is used for treating various cancers. Cancers that are treated with this drug include breast, ovarian, pancreatic, and lung cancers. It was extracted from the Pacific yew tree. Paclitaxel can act against cancer cells by interfering with cell division.

How Does Paclitaxel Work?

Paclitaxel works by interfering with the process of cell division. Every cell has a structure called the cytoskeleton. This structure acts as a framework and transport system. Part of this system consists of microtubules, which are small tubes that constantly grow and shrink, allowing the cell to function properly.

Some drugs, such as Colchicine, damage cells by disrupting microtubule function. Paclitaxel works oppositely. Instead of breaking them down, it locks them in place, making its structure more stable.

Paclitaxel gets attached to tubulin, which is the basic building material of microtubules. When Paclitaxel binds to tubulin, microtubules cannot grow or shrink as they once did. Because of this, the cell cannot move materials inside itself and hence, cannot divide properly.

This process is very important during cell division (mitosis), when chromosomes need microtubules to move correctly. When this process fails, the cancer cell cannot divide and survive.

In addition, Paclitaxel also helps cancer cells die by affecting a protein called B-cell leukemia 2 (Bcl-2), which normally prevents cell death. Paclitaxel acts by binding to the Bcl-2 protein and preventing its protective function, allowing the cancer cell to die. This is called apoptosis. Paclitaxel can stop cancer cell division and can lead to cancer cell death naturally.

How Is Paclitaxel Used?

Paclitaxel is a cancer medicine in the form of an injection, which is given intravenously (IV). A nurse or doctor gives it in a hospital or a clinic. The injection is slowly given over three hours or sometimes 24 hours.

It is mainly used for cancers like ovarian cancer, breast cancer, or lung cancer. Paclitaxel is given once every three weeks. In the case of Kaposi’s sarcoma, it may be given every 2 or 3 weeks.

While giving this medicine, the patient is closely observed for their response. If the patient develops any side effects or is not tolerating the medicine, the doctor may stop the medicine or adjust the dosage.

Patients need to tell their doctor about how they are feeling during treatment. If they develop any side effects, they should be reported to the concerned doctor. Patients should also ask the doctor or pharmacist for written information about the medicine. This helps them understand how it works and what can be expected.

Dosage

Ovarian Cancer Treatment Among Adults:

For patients who have not received any treatment before, this medicine can be given in two ways. These include:

1. Paclitaxel 175 milligrams per square meter (mg/m2) is given through your vein for over three hours. After this, another medicine, Cisplatin 75 mg/m2, is given through the vein. This treatment is repeated once every three weeks.
2. Paclitaxel 135 mg/m2 is given for 24 hours very slowly through your vein. This is again followed by Cisplatin of 75 mg/m2.

For patients who have already received treatment, only Paclitaxel is selected for administration.

• It is 135 mg/m2 given through your vein for 3 hours every 3 weeks, or 175 mg/m2 can be given as a higher dose. This is also given once every three weeks, over three hours through the vein.

Breast Cancer Treatment Among Adults:

If your cancer has spread to other parts of the body, or if it comes back within six months after finishing earlier chemotherapy, the following treatment may be used:

• Paclitaxel 175 mg/m2 is given through a vein over about three hours. This treatment is to be repeated every three weeks.

Breast Cancer Adjuvant (Adults):

For patients who have breast cancer and the cancer has spread to the lymph nodes, this treatment is preferred after the surgery. This treatment is given to lower the risk of the cancer coming back.

1. Paclitaxel 175 mg/m2 is given over 4 treatment cycles.
2. Paclitaxel is given after completion of chemotherapy that contains Doxorubicin.

Non-Small Cell Lung Cancer (Adult):

Paclitaxel 135 mg/m2 is given intravenously (IV) over 24 hours, followed by Cisplatin IV every three weeks.

Kaposi's Sarcoma:

For patients with acquired immunodeficiency syndrome (AIDS)-related Kaposi's sarcoma:

• Paclitaxel 135 mg/m2 is given IV over three hours every three weeks or 100 mg/m2 IV over three hours every two weeks.

For Patients With Solid Tumors Like Ovary, Breast, and NSCLC (Non-Small Cell Lung Cancer):

Courses must only be repeated once the platelet count is at least 100,000 cells per cubic millimeter (mm3) and the neutrophil count is at least 1500 cells per mm3.

Dosage Form:

For Injectable Suspension for Intravenous Use:

Paclitaxel is available as a dry powder, white to light yellow in color. Each vial contains 100 milligrams of Paclitaxel. Paclitaxel is attached to a natural protein called albumin. This protein is found in the blood. Albumin helps the drug Paclitaxel to work better. The vial should be mixed with liquid before it is given through the vein.

How Paclitaxel Is Administered?

This medication is taken as prescribed by your doctor.

• A doctor or a trained nurse can give this in a hospital or a clinic.
• When medicine is given to you, even after it is completed, you should be monitored closely for any allergic reactions, such as itching, rash, breathing difficulty, or swelling.
• If you develop an allergy to this medicine, it should not be given again.
• As this medicine is given IV, the injection site should be closely monitored to prevent leakage into the surrounding skin. If it leaks into the surrounding spaces, it may cause pain or damage.
• If the medicine is given slowly over about 30 minutes, it may help reduce infusion-related reactions in a few patients.
• If you are found to be sensitive to Paclitaxel, the doctor may use preventive medicines before administering it. This may reduce the chances of reactions.

For Patients

What Are the Different Types of Cancers?

Cancer is not a single disease; it is a group of diseases. In cancer, some of the cells in the body grow uncontrollably. Cancers are named based on the type of tissue or fluid in which they start and the part from which they grow. Some of the cancers exhibit mixed features.

The types of cancer include:

• Carcinoma:

These are cancers that develop in the skin or the lining of organs.

• Lymphoma:

Cancers that are related to the lymph system.

• Sarcoma:

These cancers are related to bones, muscles, or connective tissues.

• Leukemia:

The cancers that are related to blood and bone marrow.

• Myeloma:

Myeloma cancers are related to plasma cells of the bone marrow.

Things to Consider:

Before the Administration of the Drug:

Important things to tell your doctor and pharmacist include:

• If you are allergic to Paclitaxel or to any other drugs.
• If you have an allergy to Polyoxyethylene castor oil, as this is used in some injections.
• Some medicines may contain these ingredients, and hence, if you are not aware of the ingredients of any drug, it is better to ask your doctor or pharmacist to know the ingredients and confirm that they do not contain the ingredients that concern you.

Inform your doctor regarding all medicines that you are taking. These include:

• Prescription medicines.
• Over-the-counter medicines.
• Vitamins and minerals.
• Herbal or traditional medicines.

These things are important because some medicines may interact with Paclitaxel. This may need to be adjusted by doing dose changes or closely monitoring. Even though the prescribed drugs do not contain the drug you are allergic to, you mention it. This is important for your safety.

Medical History:

This is very important for both the doctor and patient.

• You must tell your doctor about any health issues like liver problems, heart diseases, or anything without fail.
• You must inform your doctor if you are planning a pregnancy or if you are pregnant.
• Take care not to get pregnant while on Paclitaxel. This medicine may harm the unborn baby.
• If you want to use birth control pills while on Paclitaxel, talk to your doctor about the safety of birth control pills.
• If you get pregnant during the treatment of Paclitaxel, inform your doctor immediately.

How to Prepare Paclitaxel Before Administering It?

The preparation is performed very carefully in a clean, sterile environment by healthcare staff.

• A vial of Paclitaxel is mixed with 20 milliliters of normal saline.
• The saline is added very slowly over a minute. This is done using a syringe.
• The liquid added should slowly seep through the vial wall, not be directly sprayed.
• After adding the liquid, the vial should be left undisturbed for 5 minutes. This allows the liquid to get absorbed into the powder.
• Shaking the vial should be avoided to prevent foam formation.
• If foam or clumps appear, leave the vial for 15 minutes to allow everything to settle.

After Paclitaxel Is Administered:

After the administration of Paclitaxel, the patient should be kept under observation for a minimum of six to eight days at the hospital. This is done to monitor for any side effects or harmful reactions.

• You are asked to stay close to the treatment center for a few weeks. This is because, in the event of any problems, medical help can be provided immediately.

What Side Effects Can Paclitaxel Medication Cause?

Paclitaxel can cause the following side effects. These include:

• At the injection site, pain, redness, swelling, and sores may develop.
• It may cause a burning, tingling sensation in the hands or feet.
• The patient may experience joint pain or muscle pain.
• Loose stools or diarrhea may occur.
• Nausea or vomiting may be observed.
• Some may experience hair loss.
• Sores or ulcers may be seen in the mouth.

Serious side effects should be reported and addressed immediately. These are:

• Breathing difficulty or shortness of breath.
• Your skin may become pale.
• You may experience severe tiredness or weakness.
• If you notice bleeding or bruising.
• If you notice chest pain.
• If you feel slow, fast, or irregular heartbeats.

How Effective Is Paclitaxel?

Paclitaxel is found to be effective when given every week, especially in the case of advanced breast cancer. This medicine can be used alone or in combination with other drugs. It can be used along with radiation therapy or with targeted medicines like Trastuzumab.

This medicine worked really well, even among those who had already received chemotherapy.

Some studies have shown good results with Paclitaxel.

• When this medicine was used alone, it was successful in controlling cancer among 87 out of 100 patients.
• When this medicine was used along with other cancer medicines, too, it helped around 88 out of 100 patients.
• Some studies have shown that when this medicine is used with radiation therapy, it helps almost all patients.

Patients with HER2-positive (a more aggressive type of cancer), when Paclitaxel is given with Trastuzumab, show benefit in almost half to most of the patients.

Paclitaxel can have a few side effects, but some serious ones include:

• Decreased white blood cells. This side effect can increase the risk of infections among patients.
• Some may experience numbness or tingling in the hands or feet.

How to Store and Dispose of Paclitaxel?

Paclitaxel comes in a powder form. Each vial contains 100 milligrams of Paclitaxel and is used only once. Each vial has its own packing. This medicine should be kept at a normal room temperature. It should be kept in its box to avoid light exposure.

What Should Be Done in the Case of Paclitaxel Overdose?

If this medicine is taken in excess by mistake, call a poison control helpline immediately. If the person suffers from seizures or difficulty in breathing, emergency care should be contacted immediately.

What Should Be Done if a Dose of Paclitaxel Is Missed?

In case you miss the dosage of Paclitaxel, you should seek help from your doctor.

For Doctors:

Warning and Precautions Before Prescribing

If a patient experiences neutropenia (low white blood cell count), their ability to fight infections is reduced. It may be observed when the dose of this medicine is increased.

When treatment may be stopped or delayed:

• Among patients receiving Paclitaxel with Gemcitabine, if they feel their white blood cell or platelet counts drop to very low levels, they should stop or delay the medicine.
• The next cycle may be delayed if they are still found to have low levels of white blood cells.
• Whenever the treatment is resumed, the dosage is lowered to improve safety.
• When Paclitaxel causes side effects like numbness, tingling, or a burning sensation in the hands and feet, and if they become severe, the medicines are stopped to improve symptoms or paused to improve symptoms. Once the symptoms improve, the treatment may be resumed with a lower dosage.
• Patients taking Paclitaxel may have an increased risk of serious infection. This medicine may cause bloodstream infections in 5 out of 100 patients.
• Patients with bile duct blockage and stents are at higher risk for serious infections.
• If a patient develops a fever, antibiotics should be started immediately, even if the blood counts are normal.

Paclitaxel should not be used in the following situations:

• If a patient has low white blood cells, particularly neutrophils, Paclitaxel should not be given. If neutrophil counts are less than 1500, this increases the risk of serious infections.
• If the patient has exhibited an allergic reaction in the past, Paclitaxel should be avoided.

In these cases, the doctor will choose a different treatment or wait until it is safe to give the medicine.

Drug Interactions

Paclitaxel may be affected by other medicines. If a patient is taking other medicines, such as prescription drugs, over-the-counter medicines, vitamins, or herbal products, these may affect the drug Paclitaxel. Hence, all information regarding the drugs you are taking must be given to your doctor.

Certain liver enzymes may break down Paclitaxel. Some medicines may affect these enzymes, either speeding them up or slowing them down. If this happens, Paclitaxel may not work properly and may also cause side effects.

Doctors should be extra careful whenever they prescribe Paclitaxel along with other drugs, especially those affecting liver enzymes.

Some of the Other Specifications:

• Paclitaxel should not be given to pregnant women as it may harm the unborn baby.
• Paclitaxel can pass through breast milk, and hence it should not be given to breastfeeding women.
• Paclitaxel is not given to children. Its safety in children is not known.

Conclusion

Paclitaxel is a medicine used for many cancers, but is particularly used for breast cancer. It is available in the form of an injection and given intravenously. Before administering this drug, a detailed discussion between the patient and the doctor is necessary. Both should be aware of Paclitaxel's side effects, preparation, indications, and contraindications. The patient should give a detailed medical history and any other drugs being taken to the concerned doctor. All these will help in the success of the drug action and its usefulness. You can consult a cancer specialist for better clarity.

Key Takeaways

• Paclitaxel is used for treating many cancers, such as breast cancer, ovarian cancer, and lung cancer.
• Paclitaxel works by interfering with cell division and has side effects.
• Paclitaxel is contraindicated in pregnant and breastfeeding women.