Page 314 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

292 PART III Therapeutic Modalities for the Cancer Patient

TABLE 16.4 Suggested Dosages of Analgesics to Alleviate Chronic Cancer Pain in Dogs a
Drug Dosage Comments
VetBooks.ir Amantadine 4–5 mg/kg given orally (PO) every 24 hours Loose stools and excess GI gas can be seen at

higher doses for a few days. Should not be com-
(q24hrs)
bined with drugs such as selegiline or sertraline
until more is known about drug interactions.
Should not be used in seizure patients, and
caution should be exercised in patients in heart
failure.
Amitriptyline 0.5–2 mg/kg PO q24hrs Has not been evaluated for clinical toxicity in the
dog. Should be used cautiously in combination
with tramadol.
Fentanyl, transdermal 2–5 mcg/kg/hrs Can be very useful in short-term control of cancer
pain. Long-term use is limited by need to
change patch every 4–7 days. Clinicians should
be aware of the abuse potential and danger to
children of fentanyl patches.
Gabapentin 3–10 mg/kg PO q6–12hrs Has not been evaluated in dogs as an analgesic.
Most likely side effect is sedation.
Grapiprant 2 mg/kg PO q24hrs Mild GI disturbances can be observed but generally
are infrequent. Other EP 4 receptor antago-
nists (piprant NSAIDs) are being evaluated as
anticancer agents for humans, but no studies
of grapiprant in veterinary cancer patients have
been performed.
Pamidronate 1–1.5 mg/kg diluted in 4 mL/kg normal saline Inhibits osteoclast activity and thus provides anal-
(NaCl), given intravenously (IV) slowly over 2 hrs. gesia only in patients suffering from a primary
Repeat every 4–6 wks. or metastatic bone tumor that is causing oste-
olysis. Nephrotoxicity may be a concern.
Paracetamol (acetaminophen) + codeine (30 or 10–15 mg/kg of acetaminophen PO q12hrs Sedation can be seen as a side effect with doses at
60 mg) or above 2 mg/kg codeine.
Paracetamol (acetaminophen) 10–15 mg/kg PO q12hrs Associated with fewer GI side effects than regular
NSAIDs; has not been noted to be associ-
ated with renal toxicity. However, toxicity has
not been evaluated clinically in dogs. Can be
combined with regular NSAIDs for severe cancer
pain, but combination has not been evaluated
for toxicity.
Prednisolone 0.25–1 mg/kg PO q12–24hrs; taper to q48hrs if Do NOT use concurrently with NSAIDs. Can be
possible after 14 days particularly useful in providing analgesia
when a significant inflammatory component is
associated with the tumor, and for CNS or nerve
tumors.
Prednisone 0.25–1 mg/kg PO q12–24hrs; taper to q48hrs if Do NOT use concurrently with NSAIDs. Can be
possible after 14 days particularly useful in providing analgesia
when a significant inflammatory component is
associated with the tumor and for CNS or nerve
tumors. In animals with diminished liver func-
tion, prednisolone may be more appropriate.
Tramadol 4–5 mg/kg PO q6–12hrs Has not been evaluated for efficacy or toxicity in
dogs. On balance, tramadol does not appear to
be effective for osteoarthritis pain.
Zoledronate 0.1–0.2 mg/kg in 50–100 mL 0.9% NaCl, given IV This drug inhibits osteoclast activity and can
over 15 min Maximum of 4 mg per dog; can be provide analgesia in cases suffering from a pri-
repeated q21–28days mary or metastatic bone tumor that is causing
osteolysis. Nephrotoxicity may be a concern.
CNS, Central nervous system; GI, gastrointestinal; NSAIDs, nonsteroidal antiinflammatory drugs; PO, oral.
Empty cells denote that the aspect of validity has not been determined.
a None of these drugs have been evaluated for efficacy in the treatment of cancer pain. None of these drugs are approved or licensed for use in chronic cancer pain. Nonsteroidal antiinflammatory
drugs (NSAIDs) have not been included in this table. NSAIDs should be used as a first line of pain relief if it is clinically appropriate to use them and should be used at their approved dosage. The dosages
given are based on the authors’ experience and the experience of others working in the area of clinical cancer pain control.