So Atticus went to the vet this morning for his second chemotherapy drug, cyclophosphamide.  Before they gave him the pill, they ran the regular tests and checked his weight…he gained a pound and his blood test results were “Phenomenal”!!!

So, cyclophosphamide- the vet gave it by mouth. They gave us a Diuretic to encourage him to pee and prevent the side effects discussed below (excerpt from Lymphoma: Which Chemotherapy Protocol and Why? by Ruthanne Chun, DVM, Dipl. ACVIM (Oncology):

Cyclophosphamide, an alkylating agent, may be administered
orally or intravenously. When given orally, absorption
is excellent and bioavailability is as good as with intravenous
administration. The potential for myelosuppression and gastrointestinal
upset after cyclophosphamide is moderate. The
specific side effect of major concern with cyclophosphamide
is sterile hemorrhagic cystitis (SHC), which occurs secondary
to elimination of irritating metabolites through the urine.
SHC may occur after oral or intravenous administration.
This side effect is not cumulative; it may happen after the first
dose of cyclophosphamide. Because there is no effective treatment
for SHC, prevention is key. Administration of a single
dose of furosemide at the time of cyclophosphamide is reported
to greatly diminish the development of SHC. Also,
simple management issues such as allowing the patient out to
urinate frequently for 3 days after drug administration and
encouraging intake of plenty of fluids may prevent SHC.

The following excerpt is from http://en.wikipedia.org/wiki/Cyclophosphamide:

Cyclophosphamide is converted by mixed function oxidaseenzymes in the liver to active metabolites[12]. The main active metabolite is 4-hydroxycyclophosphamide, which exists in equilibrium with its tautomer, aldophosphamide. Most of the aldophosphamide is oxidised by the enzyme aldehyde dehydrogenase (ALDH) to make carboxyphosphamide. A small proportion of aldophosphamide is converted into phosphoramide mustard and acrolein. Acrolein is toxic to the bladderepithelium and can lead to hemorrhagic cystitis. This can be prevented through the use of aggressive hydration and/or mesna.The main effect of cyclophosphamide is due to its metabolite phosphoramide mustard. This metabolite is only formed in cells that have low levels of ALDH.

Phosphoramide mustard forms DNA crosslinks between (interstrand crosslinkages) and within (intrastrand crosslinkages) DNA strands at guanine N-7 positions. This is irreversible and leads to cell death.

Cyclophosphamide has relatively little typical chemotherapy toxicity as ALDHs are present in relatively large concentrations in bone marrow stem cells, liver and intestinalepithelium. ALDHs protect these actively proliferating tissues against toxic effects phosphoramide mustard and acrolein by converting aldophosphamide to carboxyphosphamide that does not give rise to the toxic metabolites (phosphoramide mustard and acrolein).

The articles sound scary but Krisann says he he is peeing a lot and drinking a lot also which makes me feel good.

He continues to do really well, his appetite is endless, no unusual eliminations, no fever, rash, furloss…He is doing great on chemotherapy!

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