Dr. Smith called a little while ago in response to a v-mail I’d left at VIMP because we didn’t have an appointment on our discharge orders. He wants us to meet him at VIMP at 8 a.m. on Tuesday so he can do Mina’s CBC. He’s been consulting with Dr. Birnbaum and wants to be part of Mina’s treatment and I’m fine with that. We both like him.

If Mina’s white cell count is within normal limits, then we’re going to skip the scheduled Vincristine IV and, instead, administer the last drug in the first quarter of the protocol, doxorubicin.

Dr. Birnbaum wants her spleen to shrink more. Mina has an aggressive cancer and they want to attack it aggressively. God, this scares me. If it doesn’t work then it’s likely her vets will recommend not continuing with the chemotherapy. That scares me. We’ve had such a good few days that I was getting hopeful again and I feel like, now, all hope rests on this one treatment.

Here’s some information on doxorubicin that should curl your hair:

Adriamyacin (Doxorubicin). Adriamycin works by impairing DNA and hinders cell division in cancer cells. This drug is commonly regarded as one of the most effective chemotherapy drugs, but it also is widely reported as having potential for significant harmful side effects.

Here’s the info on side effects from the link above:

Doxorubicin is given only as an intravenous injectable. It is given slowly over a 10 minute or so period in an IV drip rather than as a single quick shot. It is very irritating to the skin so that those who work with it must wear gloves, gowns and protective goggles or masks.

If the injection does not go intravenously and some doxorubicin leaks into the tissue surrounding the vein, an extreme reaction occurs in the tissue. (This can happen if multiple attempts at catheterizing the vein leave some leakage points in the vein, or if the pet chews the catheter part way out during the administration.) The tissue in contact with the doxorubicin will die and rot away, leaving a large unhealing wound. Because of the DNA-poisoning nature of doxorubicin, this wound may actually expand or may simply not heal. Amputation may be required. If the tissue exposure is treated immediately with special flushes and cortisones and special wraps, this disaster has a chance of being averted. In general, a well-seated IV line is a priority when doxorubicin is administered.

Acute allergic reactions (causing facial swelling, hives, vomiting, and possibly heart rhythm problems) are common enough that most patients are pretreated with diphenhydramine, a common antihistamine, to block any such reaction.

SIDE EFFECTS

Because doxorubicin attacks rapidly dividing cells it is also toxic to normal cells with high division rates: hair follicle cells, bone marrow cells, and intestinal cells. It is also toxic to muscle cells, particularly heart muscle cells.

Doxorubicin is famous for “cumulative cardiotoxicity.” This means that there is a maximum amount of doxorubicin a patient can take during its lifetime before its heart will be poisoned. The heart dilates, becomes incapable of effective pumping, and does not respond to therapy. This obviously is a side effect that must be avoided, which means that the total number of doxorubicin treatments is limited no matter what the cancer is doing. The total dose of doxorubicin widely held to be the “ceiling” is 240 mg/M2 (M2 = square meters of body surface area, a more accurate form of dosing than going by weight) but toxicity can be seen at small levels. Many oncologists will ultrasound the patient’s heart to assess function prior to delivering a dose of doxorubicin.

Bone marrow toxicities are common with most chemotherapy drugs as this is one of the areas where the body normally has many rapidly dividing cells. Red blood cells, which carry oxygen and remove carbon dioxide, are made here. The white blood cells that make up our immune systems are born here. The platelets that allow our blood to clot also arise here. Usually it is the white blood cells and platelets that are most vulnerable. Monitoring tests are needed because if a line of cells becomes suppressed, the oncologist may need to postpone a drug dose, modify a dose, or change to another treatment to make up for the missing blood cells.

Upset stomachs, generally short-lived, are not unusual 2 to 5 days after doxorubicin use. Nausea is usually controlled with medication.

Patients on doxorubicin will have trouble growing in fur over shaved areas. Whiskers are often lost and do not regrow.

In cats, doxorubicin is also a kidney toxin and blood test monitoring is needed to make sure kidney function remains acceptable.

Urine will look especially orange for a day or two post-administration. Owners should avoid handling this urine (wear gloves).

Now, you know why this drug scares me. It’s what we all know about chemotherapy – it’s almost as bad as the disease.

Pray for Mina.

s.

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