Page 408 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Toxicity of Over-the-Counter Drugs Chapter | 21 375

VetBooks.ir changes such as snapping, pacing, and head shaking, 6% agents. Prazosin can be given at 1 2 mg every 8 h or
phentolamine can be given at 0.1 mg/kg IV as needed
had seizures, 5% had depression, 5% were weak, and 5%
(Papich, 1990; Ooms and Khan, 2001).
were apprehensive. Hyperthermia was reported in 28% of
these dogs. Severe CNS stimulation sometimes requires treatment
with more than one anticonvulsant. Acepromazine can be
Clinical Chemistry used to treat pseudoephedrine, ephedrine, or PPA toxico-
sis. Acepromazine is given at a dose of 0.05 1.0 mg/kg
Hypokalemia, hyperglycemia, and hyperinsulinemia are
IM, IV or SC, starting with a low dose and adding more
usually reported in dogs with decongestant toxicosis
as needed. Alternately, chlorpromazine is given IM or IV
(Means, 1999, 2005). Changes reported in a dog that had
at a dose of 0.5 1.0 mg/kg, starting with a low dose and
ingested PPA included hypoglycemia, mild hyperbiliru-
increasing as needed. If needed, phenobarbital can be
biemia, and elevated ALT, ALP, BUN, creatinine, and
given for refractory seizures at a starting dose of 3 mg/kg
CK. Blood pH and calcium concentrations were elevated.
to effect (Means, 1999, 2005). Isoflurane anesthesia has
Polycythemia and thrombocytopenia were noted. A urine
been recommended to control severe clinical signs (Ooms
sample contained blood, hemoglobin or myoglobin, and
and Khan, 2001). Use of benzodiazepines is considered
protein. Elevated serum cardiac troponin concentrations
contraindicated because the dissociative effects of this
indicate myocardial damage (Crandell and Ware, 2005;
drug class can exacerbate clinical signs of sympathomi-
Ginn et al., 2013).
metic amines.
Fluid therapy and cautious urinary acidification helps
Diagnosis and Management promote excretion (Ooms and Khan, 2001; Means, 2005).
Diagnosis of decongestant toxicosis is usually based on Urinary acidifiers enhance excretion of pseudoephedrine
history and clinical signs. Some laboratories are able to in humans, and may be used in dogs, but acid base status
test for pseudoephedrine, ephedrine, and PPA in plasma must be monitored closely. The dose for ascorbic acid is
or urine to confirm exposure, but it takes hours or days 20 30 mg/kg IM or IV every 8 h. Ammonium chloride is
for results to be available. Treatment must be initiated in given 50 mg/kg PO every 6 h. Glucose is added to intra-
the poisoning case before analytical results are available. venous fluids to treat hypoglycemia. Overhydration must
Treatment consists of detoxification, symptomatic, and be avoided to prevent pulmonary edema in the hyperten-
supportive care. Emetics use is contraindicated in dogs sive patient.
with central nervous system signs due to the potential for Adverse clinical signs associated with decongestants
aspiration. Gastric lavage can be performed in the stabi- can last for 72 h or more (Means, 2005). One dog with
lized, anesthetized, and intubated patient after a large severe clinical signs after PPA ingestion required 6 days
ingestion. Activated charcoal and cathartic have been of hospitalization (Crandell and Ware, 2005); most ani-
recommended. Blood pressure, ECG, and body tempera- mals respond to treatment more rapidly. Clinical signs
ture should be monitored closely, and CBC, serum chem- that have been associated with an unfavorable outcome
istry, and acid base status should be monitored every include uncontrollable seizures, DIC, myoglobinuria, and
day or so. Cardiac troponin can be measured to diagnose head-bobbing. Ooms and Khan (2001) report that 26 out
myocardial damage. of 34 dogs recovered with treatment, usually within
Tachycardia is treated with β-blockers. Propranolol 10 48 h after ingestion of a ma huang and guarana com-
can be administered at a dose of 0.02 0.06 mg/kg slowly bination drug. The remaining eight dogs died or were
by IV (Means, 1999, 2005; Ooms and Khan, 2001). euthanized.
Propranolol therapy will help to stabilize hypokalemia.
Alternately, lidocaine has been used at a dose of 2 mg/kg Antihistamines
IV by intermittent bolus or by continuous infusion at a
rate of 80 μg/kg/min (Crandell and Ware, 2005). Crandell Antihistamines act by competitive inhibition of histamine
and Ware (2005) recommend atenolol at 0.2 mg/kg every at histamine receptors. Compounds referred to as antihis-
12 h and enalapril 0.5 mg/kg every 12 h, both given tamines in this section are the H 1 histamine receptor
orally, to support myocardial function for PPA toxicosis. antagonists. H 2 histamine receptor antagonists are also
Ginn et al. (2013) used a combination of drugs, including sold over the counter, and are covered later, with drugs
esmolol, via bolus (2 μg/kg IV) and continuous rate infu- affecting the gastrointestinal system. They will be referred
sion (30 μg/kg/min), in addition to aggressive supportive to as H 2 histamine receptor antagonists (or H 2 -blockers).
care in a dog that ingested a large dose of PPA. Papich Many antihistamines, including brompheniramine,
(1990) recommend atropine at a dose of 0.04 mg/kg SC chlorpheniramine, clemastine, diphenhydramine, loratadine,
or IV. High peripheral vascular resistance and hyperten- and triprolidine, are found in allergy, cold, and flu formula-
sion are relieved with α-adrenergic receptor-blocking tions. Others, such as dimenhydrinate and meclizine, are