Responding to accidental atomoxetine ingestion - Veterinary Medicine
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Responding to accidental atomoxetine ingestion
At fairly low dosages, atomoxetine—a drug in human medicine to treat ADHD—can be toxic in dogs and cats. Medical management of this toxicosis varies by species.


VETERINARY MEDICINE


DECONTAMINATION

Induce emesis in animals that have been recently exposed (< 30 minutes) and are exhibiting no clinical signs. In cats, give xylazine (0.44 mg/kg intramuscularly) to induce emesis,7 and in dogs, give apomorphine (0.03 mg/kg intravenously; 0.04 mg/kg intramuscularly).7 If apomorphine is only available in tablet form, it may be administered into the conjunctival sac. When using the ocular method, a quarter of a 6-mg tablet (in any sized dog) should be crushed, diluted with a few drops of saline solution, and administered into the conjunctival sac. After emesis has occurred, gently rinse the conjunctival sac with saline solution to reduce the risk for ocular irritation.

Alternatively in dogs, 3% active hydrogen peroxide can be orally administered at a dose of 1 to 2 ml/kg (generally not exceeding 45 ml as a total dose). This dose may be repeated just once since multiple doses of hydrogen peroxide may result in gastritis.8 Hydrogen peroxide is generally not recommended for cats because of their increased risk for gastritis.9

For dose exposures > 2 mg/kg in dogs and cats, a single dose of activated charcoal with a cathartic can be administered to hinder absorption (1 g/kg of activated charcoal diluted in water to achieve a 1 g/10 ml concentration or 10 ml/kg of a 10% activated charcoal suspension) may be warranted.7 Collect baseline electrolyte values at presentation, and monitor them for four hours after activated charcoal administration to assess for changes to the patient's sodium concentration.

MONITORING

Closely monitor heart rate and blood pressure in exposed patients. Baseline electrolyte values should be obtained and monitored for changes as marked gastrointestinal effects develop or hydration becomes a concern. In cases in which activated charcoal has been administered, monitor electrolyte values for at least four hours (see "Decontamination" above).

Marked tremor activity may result in hyperthermia and rhabdomyolysis with subsequent hyperkalemia and renal damage; thus, in patients exhibiting serious clinical signs, also monitor renal indices.

Monitor patients that are asymptomatic after ingestion for six hours before their release.

TREATMENT OF TOXICOSIS

If a patient has developed agitation or hyperactivity and is normotensive or hypertensive, acepromazine at a dosage of 0.02 mg/kg intravenously or intramuscularly may be administered for sedation. Tremors may be controlled with methocarbamol (50 to 220 mg/kg intravenously slowly to effect, not to exceed 330 mg/kg/day). Seizure activity can be treated with diazepam (0.5 to 2 mg/kg intravenously in dogs, 0.25 to 1 mg/kg intravenously in cats starting at lower doses and given to effect), but administer this drug with caution; occasionally patients may develop paradoxical excitation after administration. Alternatively, a barbiturate such as phenobarbital (2 to 5 mg/kg intravenously to effect, may be repeated at 20-minute intervals up to two times), gas anesthesia, or propofol (5 to 6 mg/kg intravenously) may be given to control seizures.7

Tachycardia and hypertension may resolve after sedation. If tachycardia persists and the patient is normotensive, propranolol (0.02 to 0.06 mg/kg intravenously slowly to effect), a nonselective beta-adrenergic antagonist, may be administered to obtain the desired heart rate.7 A nitroprusside continuous-rate infusion may be given to manage hypertension (> 200 mm Hg systolic arterial blood pressure). Administer an initial a dose of 1 or 2 g/kg/min in dogs (0.5 g/kg/min in cats), and then increase the dose incrementally every three to five minutes until the target blood pressure is attained. The blood pressure should be reduced by 25% over four hours to allow the cerebral vessels to readapt.7

If tremor activity occurs, fluid therapy (balanced, isotonic crystalloid) is indicated to aid in thermoregulation and provide renal support. Fluids should be administered intravenously starting at the maintenance rate of 45 to 60 ml/kg/day, adjusting for ongoing needs and blood pressure and hydration changes. If fluids are administered, the patient should be monitored closely for hypertension and potential fluid overload.


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Source: VETERINARY MEDICINE,
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