Xylitol and Methylxanthines - Chocolate

Question 1

Uses of xylitol

Answer 1

sugar substitute in foods, use in dental products, flavouring in some meds, some parenteral nutritional solutions

Question 2

source of xylitol

Answer 2

accidental ingestion of xylitol-sweetened products

Question 3

Toxicity of xylitol

Answer 3

dogs most susceptible
toxicity reported in ferrets
no effects in horses, rats, some soviet dogs

Question 4

Toxicokinetics of xylitol

Answer 4

absorbed readily but incompletely from GIT

can be converted to glucose then glycogen in the liver

Question 5

MoA of xylitol

Answer 5

potent promoter of insulin release resulting in severe hypoglycaemia
larger doses can cause liver failure

Question 6

Clinical signs of xylitol toxicity

Answer 6

hypoglycaemia can occur within 30-60mins
weakness, ataxia, collapse, seizures
later onset lethargy, vomiting, liver failure, coagulopathy
dogs with liver failure may not show hypoglycemia
dogs with hypoglycaemia do not always go onto develop liver failure

Question 7

Liver lesions expected in a dog with liver failure due to xylitol toxicity

Answer 7

severe hepatocyte loss or atrophy and hepatic necrosis

Question 8

Diagnosis of xylitol toxicosis

Answer 8

hypoglycaemia +/- hypokalemia, hypophosphatemia

Liver failure - ALT elevation, ALP, Tbilli, prolonged PT/PTT, thrombocytopenia

Question 9

Treatment of xylitol toxicosis

Answer 9

decontamination by induced vomiting, activated charcoal not effective
50% dextrose IV followed by IV infusion until blood glucose returns to normal
oral feeding of high carb diet
antiemetics
fluid therapy

Question 10

Treatment of xylitol induced liver failure

Answer 10

antacids and GI
liver protectants
antibiotics may. be considered
transfusions if needed (DIC, coagulopathy), vitamin K1

Question 11

Properties of methylxanthines

Answer 11

includes caffeine, theophylline, theobromine
occurs in the cacao beans of chocolate plants
chocolate contains theobromine and caffiene

Question 12

Toxicokinetics of methylxanthine toxicosis

Answer 12

methylxanthines readily absorbed from GIT and widely distributed including CNS
metabolized by liver, undergo enterohepatic recycling
excreted in urine unchanged

Question 13

MoA of methylxanthine toxicosis

Answer 13

inhibit phosphodiesterase and antagonize adenosine receptors - cerebral cortical stimulation, seizures, myocardial contraction, smooth muscle relaxation and iduresis
Caffiene - stimulation of release of catecholamines from adrenal medulla, respiratory, vasomotor and vagal centres with greater skeletal mm. stim
Theobromine - greater cardiac stimulation than caffeine

Question 14

Clinical signs of methylxanthine toxicosis

Answer 14

Theophylline - nausea vomiting, abdominal pain, mild acidosis, tachycardia
Caffeine/theobromine - restlessness,hyperactivity, panting, vomiting
tachycardia, weakness, ataxia, diuresis, diarrhea, hyper excitability, muscle tremors, hyperthermia
clonic convulsions, progression to arrhythmias, muscle rigidity, hyperreflexia, terminal seizures, coma

Question 15

Cause of death from methylxanthine toxicity?

Answer 15

cardiac arrhythmias, resp failure, or terminal seizures

Question 16

Lab abnormalities associated with methylxanthine toxicosis?

Answer 16

low potassium, phosphorus, magnesium, elevated glucose

Question 17

Treatment of methylxanthines

Answer 17

Early decontamination
activated charcoal
IV fluid therapy
methocarbamol for tremors
diazepam/midazolam for seizures
monitor ECG
beta blockers for tachyarrhythmias