Paclitaxel

Indications

Paclitaxel Injection is indicated as first-line and subsequent therapy for the treatment of advanced carcinoma of the ovary. As first- line therapy, paclitaxel is indicated in combination with cisplatin.

Paclitaxel Injection is indicated for the adjuvant treatment of node-positive breast cancer administered sequentially to standard doxorubicin-containing combination chemotherapy. In the clinical trial, there was an overall favorable effect on disease-free and overall survival in the total population of patients with receptor-positive and receptor-negative tumors, but the benefit has been specifically demonstrated by available data (median follow-up 30 months) only in the patients with estrogen and progesterone receptor negative tumors.

Paclitaxel Injection is indicated for the treatment of breast cancer after failure of combination chemotherapy for metastatic disease or relapse within 6 months of adjuvant chemotherapy. Prior therapy should have included an anthracyclineunless clinically contraindicated. Paclitaxel Injection, in combination with cisplatin, is indicated for the first-line treatment of non-small cell lung cancer in patients who are not candidates for potentially curative surgery and/or radiation therapy. Paclitaxel Injection is indicated for the second-line treatment of AIDS-related Kaposi's sarcoma.

Pharmacology

Paclitaxel promotes microtubule formation by enhancing the action of tubulin dimers, stabilising existing microtubules and preventing their disassembly, thereby disrupting normal cell division in the late G2 mitotic phase of the cell cycle. This results in the inhibition of cell replication.

Dosage & Administration

Advanced non-small cell lung cancer: 135 mg/m2 over 24 hr or 175 mg/m2 over 3 hr, followed by cisplatin and repeated at 3 wk intervals.

Ovarian carcinoma: Primary treatment (in combination with cisplatin or carboplatin): 135 mg/m2 infused over 24 hr followed by cisplatin and repeated at 3 wk intervals. Secondary treatment (as a single agent): 135 or 175 mg/m2 infused over 3 hr once every 3 weeks.

Breast cancer: Adjuvant therapy; 2nd line monotherapy or 1st line treatment with trastuzumab: 175 mg/m2 infused over 3 hr once every 3 wk for 4 courses; when used with trastuzumab, the dose should be given the day after the 1st dose of trastuzumab or immediately after subsequent doses if well-tolerated. 1st line with doxorubicin: 220 mg/m2 over 3 hr every 3 wk, the dose to be administered 24 hr after doxorubicin.

AIDS-related Kaposi's sarcoma: 135 mg/m2 over 3 hr every 3 weeks. Alternatively, 100 mg/m2 over 3 hr every 2 wk especially in patients with poor performance status.

Interaction

Myelosuppression was more profound when given after cisplatin than with the alternate sequence (e.g., paclitaxel before cisplatin). CYP2C8 inducers e.g. carbamazepine, phenobarbital, phenytoin, rifampicin, rifapentine, and secobarbital may reduce levels or effects. CYP2C8 inhibitors e.g. gemfibrozil, ketoconazole, montelukast, and ritonavir may increase levels or effects. CYP3A4 inducers e.g. aminoglutethimide, carbamazepine, nafcillin, nevirapine, phenobarbital, phenytoin, and rifamycins may decrease the levels or effects. CYP3A4 inhibitors e.g. azole antifungals, clarithromycin, diclofenac, doxycycline, erythromycin, imatinib, isoniazid, nefazodone, nicardipine, propofol, protease inhibitors, quinidine, telithromycin, and verapamil may increase levels or effects. May increase anthracycline (eg doxorubicin, epirubicin) levels or toxicity; admin of anthracycline at least 24 hr prior to paclitaxel may reduce interaction. May decrease the absorption of cardiac glycosides (may only affect digoxin tablets); levels should be monitored.

Contraindications

History of hypersensitivity (especially macrogol glycerol ricinolate). Patients with baseline neutropenia of <1500 cells/mm3 (<1000 cells/mm3 for kaposi's sarcoma). Pregnancy and lactation. In kaposi's sarcoma, contraindicated in patients with concurrent, serious, uncontrolled infections.

Side Effects

Neutropenia, leukopenia, thrombocytopenia, anaemia, bleeding; hypersensitivity reactions (dyspnoea, flushing, chest pain, tachycardia, rash, hypotension, hypertension); bradycardia, abnormal ECG; neurotoxicity (mainly peripheral neuropathy), myalgia, arthralgia; nausea, vomiting, diarrhoea; severe mucositis, alopecia; rarely hepatic necrosis and encephalopathy, inj site reactions e.g. erythema, tenderness, skin discolouration, swelling; interstitial pneumonitis; infections (mainly UTIs and upper respiratory tract); mucosal inflammation, severe elevation in LFTs (aspartate aminotransferase and alkaline phosphatase).

Pregnancy & Lactation

Category D: There is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Precautions & Warnings

Bone marrow suppression during therapy. Monitor cardiac function if conduction abnormalities result. Premedicaton (with corticosteroid, antihistamine and histamine H2-receptor antagonist) may be required to reduce risk of hypersensitivity reaction. Discontinue, if severe reactions e.g. hypotension, dyspnoea, angioedema or urticaria occur. Caution in patients with moderate hepatic impairment. Monitor for reactions of admin. Safety and efficacy in paediatric patients have not been established. Administer before platinum derivatives (cisplatin, carboplatin) if used in combination. Hazardous agent; use appropriate precautions for handling and disposal.

Use in Special Populations

Hepatic Impairment:

Advanced non-small cell lung cancer: Do not use in severe impairment, increased risk of hepatotoxicity. For detailed dosing recommendation, consult local protocol.

Ovarian carcinoma
: Do not use in severe impairment, increased risk of hepatotoxicity. For detailed dosing recommendations,
consult local protocol.

Breast cancer
: Do not use in severe impairment, increased risk of hepatotoxicity. For detailed dosing recommendation, consult local protocol.

AIDS-related Kaposi's sarcoma
: Do not use in severe impairment, increased risk of hepatotoxicity. For detailed dosing recommendation, consult local protocol.

Overdose Effects

Complications: bone marrow suppression, peripheral neurotoxicity and mucositis. There is no known antidote. Treatment is symptom specific and supportive.

Therapeutic Class

Cytotoxic Chemotherapy

Reconstitution

Paclitaxel must be diluted before infusion. It can be diluted in 0.9% sodium chloride inj, 5% dextrose inj, 5% dextrose and 0.9% sodium chloride inj or 5% dextrose in lactated Ringer's inj to a concentration of 0.3-1.2 mg/ml.