Pharmacology for Dentistry

Chemotherapy of Malignancy 377

in metaphase.

It is used for the treatment of non small
cell lung carcinoma, breast carcinoma,
Hodgkin’s disease, ovarian carcinoma,
squamous cell carcinoma of the head and
neck, cervical squamous cell carcinoma,
renal cell cancer and Kaposi’s sarcoma.

TAXANES

PACLITAXEL

It is an alkaloid ester derived from the
western yew Taxus brevifolia.

It is a diterpenoid compound and is a
natural product with antitumour activity.

It binds specifically to the βββββ-tubulin
subunit of microtubule and appears to
antagonise the disassembly of this
cytoskeletal protein i.e. enhances
polymerization of tubulin. Arrest in mitosis
follows. The cell killing is dependent on
both drug concentration and duration of
cell exposure.

It is indicated in metastatic ovarian and
breast cancer.

Adverse effects include bone marrow
depression, hypersensitivity reactions, chest
pain, bradycardia, sensory neuropathy,
nausea, vomiting, diarrhoea, alopecia and
impaired liver function tests.

Docetaxel (DOXOTEL), a related drug,
used in metastatic breast cancer.

TOPOISOMERASE-I INHIBITORS

IRINOTECAN

It inhibits topoisomerase-I, the enzyme
which is involved in DNA replication.

It is used in the treatment of metastatic

carcinoma of colon or rectum.

Adverse effects include vomiting, di-

arrhoea, abdominal discomfort, leukopenia,

anemia, neutropenia, haemorrhage, insom-

nia and dizziness.

TOPOTECAN

Topotecan also inhibits topoisomerase I.

Adverse effects include abdominal dis-

comfort, vomiting, diarrhoea, intestinal

obstruction, nausea, stomatitis, anorexia,

bone marrow suppression (primarily neu-

tropenia, anaemia and thrombocytopenia).

It is valuable in control of metastatic

ovarian cancer, including cisplatinresistant

neoplasms.

HORMONE AND HORMONE ANTAGONISTS

These are not cytotoxic drugs. They act by

modifying the growth of hormone

dependent tumours.

FOSFESTROL (STILBOESTROL)

Fosfestrol is a synthetic non-steroidal

estrogen which is activated by the enzyme

acid phosphatase to produce stilboestrol.

Metabolism occurs primarily in the liver.

It is used as palliative treatment of dissemi-

nated mammary or prostatic carcinoma.

Adverse effects include hepatic cuta-

neous porphyria, perineal pain, erythema

and feminising effects in man.

ETHINYL ESTRADIOL

It is also indicated in palliative treat-

ment of disseminated mammary or pros-

tatic carcinoma. The detailed pharmacol-