Topotecan hydrochloride

Anticancer drug

Topotecan hydrochloride is a water-soluble derivative of camptothecin, which is the form of hydrochloride of topotecan. It is successfully developed by the SmithKline Beecham US company, and approved by the FDA in the United States in 1996. Its trade name is Hycamtin. It is applied in the treatment of ovarian cancer (OVC) as the second-line therapy.
In 1999 the US Food and Drug Administration (FDA) has approved topotecan hydrochloride as small cell lung cancer (SCLC) therapeutic drug. It has been available in the UK, Germany, France and other dozens of countries and regions. The Ⅲ clinical trials are ongoing for this medicine which is used to treat non-small cell lung cancer, cervical cancer, myelodysplastic syndrome.
Topotecan hydrochloride can enter the blood brain barrier. It has the same effect of oral and intravenous injection. The drug has low toxicity predictable bone marrow suppression, and other minor non-hematologic toxicity. Currently there are manufacturers, for clinical treatment of small cell lung cancer, ovarian cancer and other tumors.
Topotecan hydrochloride inhibits the activity of topoisomerase I, which is required for DNA replication. After intravenous injection, the product is hydrolyzed in the blood, and excreted by urinary. This product has a rapid serum clearance rate, which is 62L/h. It is widely distributed in vivo, and Its half-lifetime is about 2~3h. Preclinical trials have shown that the product has anti-tumor activity on all kinds of types of tumor. In I clinical trial, to patients with ovarian cancer that is cisplatin tolerance, this product also has significant anti-tumor effect.

Clinical studies

In a open randomized trial, 226 cases who used cisplatin or carboplatin invalid or recurrent advanced ovarian cancer women changed to this product, and compared with paclitaxel. In 112 patients who used topotecan hydrochloride, 22 cases were effective, so the effective rate was 20%. In 114 patients treated with paclitaxel, 14 cases were effective, so the effective rate was 12%. Used this product for treatment which has made significant improvement in the average time of 23 weeks, while 14 weeks for paclitaxel. In a non-controlled trial to 111 women patients with refractory advanced ovarian cancer, 16 cases were preferabe after treatment, occupied with 14%, and the curative effect average time was 16-week, and the average survival time was 52-week. In an open trial, 67 cases were ineffective treated with cisplatin and paclitaxel for advanced ovarian cancer. However, 9 cases who changed to this product were effective, and the effective rate was 13%.
The above information is edited by the chemicalbook of Kui Ming.

Side effects

It can appear toxicity of bone marrow suppression in limited doses, especially it can cause neutropenia. It often induced thrombocytopenia and anemia. Sometimes red blood cell and platelet transfusion is necessary. It can also be nausea, vomiting, hair loss, diarrhea, abdominal pain, gastritis and weakness, but all of them were mild.

Uses

It is used as antineoplastic agent.

Description

Topotecan is a chemotherapeutic agent medication and acts as a topoisomerase inhibitor. Topotecan is asynthetic, water-soluble analog of camptothecin. It is used in the form of its hydrochloride salt to treat ovarian cancer, lung cancer and other cancer types.

Chemical Properties

White Crystalline Solid

Originator

Hycamtin,SmithKline Beecham Pharmaceuticals,UK

Uses

antineoplastic; topoisomerase I inhibitor

Uses

Naturally occurring amino acid; precursor of tetrapyrroles in the biosynthesis of chlorophyll and heme. Antineoplastic (photosensitizer)

Uses

A DNA topoisomerase I inhibitor; semisynthetic analog of Camptothecin. Antineoplastic. Topotecan hydrochloride is a chemotherapy agent that is a topoisomerase 1 inhibitor.

Manufacturing Process

Camptothecin (CPT) - a compound isolated from the bark, leaves and fruit of Camptotheca acuminate (Wall M. E. et al., J. Am. Chem. Soc. 88, 3888, 1966).
10-Hydroxycamptothecin (10-HCPT) was prepared by subjecting CPT (3.2 g 0.0092 mol), 0.8 g of Pt0 (prepared by pre-reduction of 8 g of amorphous PtO2 in 80 ml of acetic acid for 1.5 h under 1 atm hydrogen pressure) and acetic acid to 1 atm of H2 for 8.5 h after which theoretical amount of H2 absorbed (slightly more than 0.4 L) and uptake of H2 gets slowed down. The reaction mixture was degassed under steam of helium and filtered through celite and washed with acetic acid (20 ml). The resulting solution was treated immediately with Pb(OAc)4 (6.4 g 0.014 mol) in portions and reaction mixture, stirred vigorously under helium for 30 min. Gumy residue was obtained on evaporation of solvent which was triturated with cold water (100 ml) to produce light brown solid. The solid was collected, washed with cold water and air dried overnight when a mixture of 10-HCPT (44%), acetyl 10- hydroxycamptothecin (10-AcHCPT, 26%) and unreacted CPT (32%) on HPLC basis was obtained. This crude mixture was combined with 150 ml of 50% acetic acid and heated under reflux conditions overnight. The reaction mixture was cooled, concentrated to 20 ml and treated with cold water (100 ml) to produce precipitate, which is filtered, washed with more cold water and dried to afford 2.1 g of solid containing 10-HCPT (70%), 10-AcCPT (1.2%) and CPT (21.3%) on the basis HPLC. Mixture was triturating with 0.5% aq HCl to dissolve the water-soluble. When insoluble CPT was removed by filtration. Water-soluble was extracted with chloroform and crystallized from boiling solution of 20% of MeOH in CHCl3 by adding EtOAC dropwise until turbidity appeared to obtain pure yellow 10-(HCPT), melting point 268°-270°C. 10-HCPT (0.364 g 0.01 mmol) and 40% aqueous dimethylamine (12 ml) was added in dichloromethane (50 ml) in which anhydrous potassium carbonate (2.17 g, 15 mmol) has been suspended. The reaction mixture was stirred at room temperature for 5 h, then filtered and solid extracted with ethylacetate (20 ml). The solvent is evaporated in vacuo giving a residue. The residue was triturated with 0.5% aq HCl (50 ml) to dissolve the water-soluble adduct. Water-soluble were partitioned with petroleum ether (3 times 50 ml) and followed by ethylacetate (3 times 50 ml). The aqueous layer was lyophilized as an off white hydrochloride salt of 9-[(dimethylamino)methyl]10- hydroxy(20S)-camptothecin (topotecan hydrochloride) yield 0.236 g (65%).

brand name

Topotecan is INN and BAN.

Therapeutic Function

Antineoplastic

General Description

Topotecan is supplied in 4-mg vials and administered IV forthe treatment of ovarian cancer, cervical cancer, and smallcell lung cancer in those patients who did not respond tofirst-line therapy. Following IV administration, the drug iswidely distributed with 10% to 35% of the agent bound toplasma proteins. There is evidence that the agent may crossthe blood-brain barrier to some extent. In plasma, an equilibriumis established between the lactone and the less activehydroxy acid with 20% of the drug present as the lactone 1hour after the infusion is complete. In contrast to irinotecan,both the lactone and the hydroxy acid bind equally well tohuman serum albumin. N-Demethylation of the tertiaryamine to give the secondary amine is mediated by CYP3A4and represents a minor route of metabolism. Glucuronidationof the parent and the phase I metabolites also occurs to a limited(10%) extent.Elimination occurs primarily in theurine, with 30% of the dose being recovered as unchangeddrug. The terminal elimination half-life is 2 to 3 hours. Themajor toxicity seen for topotecan is dose-limiting myelosuppression.Nausea and vomiting are seen in most (70%–80%)patients, along with diarrhea and abdominal pain. Other toxicitiesinclude headache myalgias, alopecia and elevation ofserum transaminases, alkaline phosphatases, and bilirubin.Microscopic hematuria (blood in the urine) may also be seen.

Biological Activity

topotecan hcl（skf104864）is an inhibitor of topoisomerase 1 and semisynthetic analogue of camptothecin [1].topotecan hcl（skf104864）has been reported to have a potent antitumor activity against tumors in murine models. in addition, topotecan hcl has also shown the potent effect against intravenously implanted p388 leukemia and both intravenously and subcutaneously implanted lewis lung carcinoma. topotecan hcl has noted the activity against subcutaneously implanted solid tumors including chemorefractory tumors and human colon carcinoma xenograft ht-29. topotecan hcl has been found to induce regressions in the lung tumor model (lewis lung carcinoma and b16 melanoma), compared to camptothecin and 9-amino-camptothecin. in the preclinical toxicology studies, topotecan hcl has been revealed to have a concentration-dependent, reversible and limited toxoicity to rapidly proliferation tissues such as bone marrow and gastro-intestinal epithelium [1].

Pharmacokinetics

Topotecan elimination is biphasic, with a terminal half-life of 2.0 to 3.5 hours. Lactone hydrolysis is rapid, and binding to serum proteins is limited to between 25 and 40%. CYP3A4-mediated N-dealkylation to monoand didealkylated metabolites occurs to a limited extent, and the O-glucuronides that form at multiple points along the metabolic path are excreted via the kidney.

Clinical Use

This active camptothecin analogue is used by the IV route in the treatment of ovarian and small cell lung cancer that has not responded to first-line therapy.

storage

Store at -20°C

References

[1] creemers gj1, lund b, verweij j. topoisomerase i inhibitors: topotecan and irenotecan. cancer treat rev. 1994 jan;20(1):73-96.