These are widely used and interfere with DNA synthesis. Side-effects include myelosuppression,
gametogenesis, alopecia and gastrointestinal irritation.
Renal toxicity has also been reported following administration of alkylating agents to old
animals - especially to cats.
The active principal of cyclophosphamide is released by hepatic microenzymes so do
not use in old animals if there is evidence of hepatic insufficiency. It is contraindicated
if the patient is anaemic (common in renal failure) as it causes further bone marrow
suppression. Haemorrhagic cystitis is a serious side-effect which necessitates withdrawal
of treatment with this drug.
Low dose rate:
50 mg/m2 body surface orally on alternate days, or for the first 4
days of each second week.
High dose rate:
100-300 mg/m2 orally every 21 days.
Cyclophosphamide is usually used in combination with vincristine or prednisone for
the treatment of lymphoma (cats and dogs) or mammary adenocarcinoma. It has also
been used for multiple myeloma.
Chlorambucil is the slowest acting of this group of drugs.
2-5 mg/m2 body surface orally on alternative days.
Usually given in combination with vincristine or prednisone.
Used for the treatment of lymphosarcoma, chronic lymphatic leukaemia and multiple
1-2 mg/m2 on alternate days until the plasma protien is normal, or 1-2 mg/m2 daily for 7-14 days.
Used mainly for multiple myeloma and other lymphoproliferative diseases. Anorexia
and vomiting may occur as well as myelosuppression