Page 432 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Toxicity of Drugs of Abuse Chapter | 22 399

VetBooks.ir (Davis et al., 1978; Diniz et al., 2003). Cerebrovascular Haloperidol at 1 mg/kg IV also decreased the clinical
effects of amphetamines on body temperature, blood pres-
hemorrhages due to hypertension, hypoglycemia, lactic
sure, heart rate, respiration, and decreased convulsions in
acidosis and cardiac failure have all been implicated in
amphetamine overdose deaths (Catravas et al., 1977). experiment dogs. Chlorpromazine and haloperidol block
Serum chemistry abnormalities in addition to lactic α-adrenergic and dopaminergic receptors. Propofol at
acidosis and hypoglycemia have been reported to include continuous rate infusion or short-acting barbiturates have
hyperkalemia, hyperphosphatemia and elevated liver also been recommended for treatment of amphetamine-
enzymes such as alanine transaminase, alkaline phospha- induced seizures. Methocarbamol has been used to control
tase, and aspartate transaminase (Catravas et al., 1977; tremors. Because of the lipophilic nature of many amphe-
Diniz et al., 2003; Llera and Volmer, 2006). tamines, IV lipid infusion could be a useful treatment
Rhabdomyolysis is evident in the presence of increased (Fitzgerald and Bronstein, 2013).
creatine kinase, myoglobinuria, and there is evidence of Cool IV fluids, ice packs, fans, cool water baths or
renal failure (Kisseberth and Trammel, 1990; Diniz et al., cool moist towels, or gastric lavage with cool water can
2003). DIC was suspected in a dog that presented with be used to treat hyperthermia. However, the shivering
bloody diarrhea, petechia of the skin, thrombocytopenia, response increases body temperature (Smith et al., 2002).
and increased prothrombin time and activated partial Cardiac arrhythmias in the amphetamine overdose
thromboplastin time subsequent to methamphetamine patient often resolve with treatment of central nervous
ingestion. Lesions in experimental dogs dosed with symptoms (Smith et al., 2002; Diniz et al., 2003).
amphetamines included subendocardial and epicardial Propranolol decreased the heart rate and blood pressure in
hemorrhage and myocardial necrosis. experiment dogs given amphetamines, but did not
Low doses of amphetamine given to horses caused improve survival (Catravas et al., 1977). The use of
increases in heart rate during rest and exercise, increased β-blockers may lead to α-receptor-mediated vasoconstric-
blood pressure, second degree AV block, and premature tion and spasms of the coronary artery. Lidocaine, procai-
ventricular contractions (Smetzer et al., 1972). namide or amiodarone have been recommended to treat
ventricular arrhythmias.
Urinary acidification with ascorbic acid or ammonium
Treatment chloride increases amphetamine excretion but should not
The prognosis for animals that have ingested ampheta- be attempted in the presence of acidosis or rhabdomyoly-
mines depends on the dose, time between exposure and sis or if acid base status cannot be monitored. Treatment
presentation, and severity of clinical signs. for acidosis and rhabdomyolysis involves fluid diuresis
Gastrointestinal decontamination should be initiated in and alkalinization. Respiratory support is sometimes
animals that present within 2 h of ingestion (Kisseberth required (Liechti et al., 2005). Treatment of hepatic dam-
and Trammel, 1990; Dumonceaux, 1995). Rapid onset of age with N-acetylcysteine has been recommended but the
clinical signs usually precludes the use of emetics. Gastric effectiveness is not known.
lavage of the sedated animal can be considered if large Based on the literature, dogs presenting with severe
doses were ingested. Activated charcoal and a cathartic toxicosis because of exposure to amphetamines have sur-
can help prevent absorption, but repeated dosing is neces- vived with aggressive therapy, but there is inadequate
sary for sustained release products. information to formulate a prognosis.
Animals should be monitored closely for neurologic Urine or plasma samples can be tested for ampheta-
symptoms, hyperthermia, cardiac arrhythmias, or respira- mines at many diagnostic laboratories. Thin-layer chro-
tory insufficiency. Baseline serum chemistries should be matography is commonly used, and immunologic assays
taken to monitor for hypoglycemia, electrolyte abnormali- are available for some compounds. GC and MS may be
ties, lactic acidosis, myoglobinuria, liver and kidney dam- used for confirmation. There has been some success using
age, etc. over-the-counter drug test kits to detect amphetamines in
Minimal external stimulation helps to prevent seizure canine urine (Teitler, 2009).
activity. Diazepam may paradoxically exacerbate the clin-
ical signs of many amphetamines (a possible exception is Other Stimulants
MDMA, see below), and is thus contraindicated (Volmer,
2005). Chlorpromazine given at 10 18 mg/kg IV was MDMA, sold as “ecstasy,” is a common illegal club drug
determined by Catravas et al. (1977) to prevent death in and will be discussed in some detail. Laws vary between
experiment dogs dosed with amphetamine when given countries and states as to the legality of the herbal stimu-
early in the progression of clinical signs. Treatment lant Khat and the related synthetic compounds mephe-
decreased hyperthermia, convulsions, hypertension, and drone and methylenedioxypyrovalerone, which have
heart rate. Normal respiration was maintained. become common in the United States where they are sold