Jul
1
Drugs for Cancer Treatment
July 1, 2009 | Leave a Comment
Cancer
The treatment of cancer is difficult because cancer cells are cells that have escaped from the controls that govern normal cell growth and differentiation of function. As a result, uncoordinated growth may develop rapidly, and cancer cells may migrate and invade other tissues. Any anti-cancer drug is therefore likely to damage normal cells, particularly actively growing cells such as those of the bone marrow, and the dose of a cytotoxic agent is often a compromise between that having the desired anti-cancer action and that causing toxicity.
The drugs used in the treatment of cancer can be divided into four main groups, which attack the cells at different points. The alkylating agents interfere with the replication and function of DNA, modify protein synthesis, and have correspondingly wide effects. The antimetabolites interfere with cell metabolism by combining with cell enzymes, or by forming abnormal proteins, or otherwise inhibiting normal development. The cytotoxic antibiotics have an action similar to that of the antimetabolites, but they also have radiomimetic properties, and combined radiotherapy may increase the risks of damage to normal cells. These antibiotics, with the exceptions of dactinomycin and bleomycin, also have undesirable cardiotoxic properties, and dosage requires careful control. Amsacrine is a synthetic cytotoxic agent with some of the properties of the antibiotic group. Some recently introduced drugs include docetaxel, gemcitabine, letrozole, paclitaxel, raltitrexed and topotecan.
The vinca alkaloids are a class apart, as they are plant substances, and act at the metaphase stage of cell division. They are used mainly in acute leukaemias and some
122 lymphomas. Vincristine is almost free from any depressive effects on bone marrow function, vinblastine has some degree of myelosuppressive activity but is less neurotoxic. Vindesine occupies an intermediate position. Etoposide is a synthetic drug with some of the properties of the vinca alkaloids. Other and unclassified cytotoxic agents include the platinum complexes carboplatin and cisplatin, used mainly in ovarian cancer, and the enzyme crisantaspase used in acute lymphoblastic leukaemia. Some cancers are hormone dependent, and the symptoms may be controlled by suitable hormone antagonists. Breast cancer for example may respond to aminoglutethimide, anastrozole, formestane, letrozole and toremifene. Prostatic cancer can be treated with anti-androgens such as fosfesterol, bicalutamidc, cyproterone and flutamide. Certain hormone analogues such as buserelin, goserelin, leuprorelin and triptorelin are also used in cancer of the prostate. A distressing side-effect of high-dose cytotoxic chemotherapy was severe and intractable nausea and vomiting, which could be so intense that patients have been known to refuse further anti-cancer treatment. The problem has since been resolved by the introduction of potent antierneties of the ondansetron type.
Myleran
carmustine BiCNU
chlorambucil Leukeran
cyclophosphamide Endoxana
estramustine Estracyt
ifosfamide Mitoxana
lomustine CCNU
melphalan Alkeran
mustine Mustine
thiotepa Thiotepa
treosulphan Treosulfan
cladribine Leustat
gemcitabine mercaptopurine methotrexate
thioguanine Lanvis
Table 8 Anti-cancer drugs. Continued on pages 124-125.
cytarabine Alexan, Cytosar
fludarabine Fludara
fluorouracil Fluoro-Uracil, Efudix
Gemzar Puri-Nethol
Maxtrex
raltitrexed Tomudex
Approved names
-cytotoxic antibiotics -
Brand names
bleomycin Bleomycin
dactinomycin Cosmegen
daunorubicin DaunoXome
doxorubicin Doxorubicin
epirubicin Pharmarubicin
idarubicin Zavedos
mitomycin Mitomycin C
mitozantrone Novantrone
vinblastine Velbe
vincristine Oncovin
vindesine Eldesine
vinorelbine Navelbine
aldesleukin
amsacrine
bicalutamide
carboplatin
dacarbazine
Proleukin
Amsidine
Casodex
Paraplatin
DTIC
cisplatin Cisplatin
docetaxel Taxotere
etoposide
Vepesid
hydroxyurea
Hydrea
iritotecan
Campto
letrozole
Ferrara
octreotide
Sandostatin
paclitaxel
Taxol
pentostatin
Nipent
procarbazine
Natulan
razoxane
Razoxin
topotecan
Hycamptin
tretinoin
Vesanoid
aminoglutethimide
Orimeten
anastrozole
Armidex
buserelin
Suprefact
Cyprostat
Drogenil
flutamide
Lentaron
formestane
goserelin
Zoladex
tamoxifen
Torero
torasemide
Casodex
Emblon, Nottam, Notwadex, Tamofen
bicalutamide
cyproterone