Managing complications of chemotherapy (Proceedings) - Veterinary Healthcare
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Managing complications of chemotherapy (Proceedings)


CVC IN BALTIMORE PROCEEDINGS


4. If the patient lethargic with gi signs, if vomiting and diarrhea are not self-limiting, or if the patient has watery or bloody diarrhea - admit to hospital for supportive care with intravenous fluids and medications:

a. Antiemetics

Metoclopramide: 0.2-0.5 mg/kg SC q8 hours or IV as a CRI at 1.1-2.2 mg/kg/day. Also for vincristine-induced ileus.

Maropitant citrate: 1 mg/kg SC q24 hours

If refractory:

Dolasetron (dogs/cats): 0.6-1 mg/kg IV slowly q12-24 hours

Ondansetron (dogs): 0.1-1 mg/kg IV slowly q8-24 hours; (cats) 0.1-0.15 mg/kg IV slowly q6-12 hours

b. H2 receptor antagonist: Famotidine 0.5-1 mg/kg IV slowly q12-24 hours

c. Antibiotic therapy if bloody vomit/diarrhea, neutropenic, or febrile – risk of sepsis

d. Enteral feeding tube if prolonged anorexia (rare)

Myelosuppression


Myelosuppressive drugs
Myelosuppressive drugs mainly affect the neutrophil count, but platelets may also be affected. The nadir for most drugs is 7 days after administration and neutropenia resolves in 2-3 days. Some drugs have variable nadirs (e.g. carboplatin, cisplatin, CCNU in cats) or can cause prolonged neutropenia (e.g. CCNU, carboplatin).

Prevention

1. Check CBC before administering myelosuppressive chemotherapy. Do not treat if <3,000 neutrophils/μL or <100,000 platelets/μL.

2. Double check chemotherapy doses. Note that some drugs require lower doses for small dogs or cats.

3. Check CBC at expected neutrophil nadir the first time patient receives each agent

a. If neutrophil count is <1,000 cells/μL, reduce subsequent doses of that drug by 20-25%.

4. If overdose, treatment with recombinant human granulocyte colony stimulating factor (rhG-CSF) is recommended (5 μg/kg q24 hours SQ for 3-5 days) starting 24 hours after treatment. Dogs and cats produce neutralizing antibodies to rhG-CSF, but should not be a problem with a short course of this drug.

Treatment

1. Usually none required.

2. For dogs, consider prophylactic antibiotics if neutrophil count <1,000 cells/μL. Options include clavamox 22 mg/kg PO q12 hours or sufadiazine-trimethoprim 15 mg/kg PO q12 hours for 5-7 days. Cats do not usually need prophylactic antibiotics. Owners can monitor rectal temperature.

3. If febrile or clinical for sepsis (lethargy, loss of appetite), admit to hospital for IV fluids and IV broad spectrum antibiotics based on culture and sensitivity (if available) or empirical use of clinician's preferred combination, for example ampicillin 22 mg/kg IV q8 hours slowly with enrofloxacin 5 mg/kg IV q12 hours (dogs), dilute and give slowly (can cause blindness in cats, so limit to 5 mg/kg/day)).

Allergic Reactions

L-asparaginase can cause a type I hypersensitivity reaction. Signs include facial swelling, erythema, urticaria, panting, agitation, vomiting, diarrhea, dyspnea, tachypnea, weakness, collapse, and hypotension.

Prevention

1. Administer by subcutaneous route.

2. After first dose, premedicate with diphenhydramine 2 mg/kg IM 20 minutes before L-asparaginase. Monitor patient for allergic reaction 30 minutes after treatment.

3. If a patient has an allergic reaction, that patient should not receive L-asparaginase again.


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Source: CVC IN BALTIMORE PROCEEDINGS,
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