Page 425 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

392 SECTION | IV Drugs of Use and Abuse

VetBooks.ir Treatment dimethyl-morphine or thebaine, which acts as a convul-
sant (Branson and Gross, 2001). Laudanum is deodor-
Decontamination for recent exposures, monitoring, and
ized tincture of opium and paregoric is camphorated
symptomatic and supportive therapy are the basis of
treatment for barbiturate overdose. Respiratory function, tincture of opium.
cardiac function, and body temperature are closely moni- Morphine sulfate is a Schedule II drug commonly
tored (Kisseberth and Trammel, 1990; Branson, 2001; used medicinally for pain control and sedation.
Volmer, 2005). Emetics are given only to the asymptom- Oxymorphone is a Schedule II morphine derivative
approved for use in dogs and cats in the United States.
atic animal if it is soon after ingestion. Gastric lavage
Oxymorphone is approximately 10 times more potent
after intubation is more appropriate when possible in ani-
than morphine (Branson and Gross, 2001). Other mor-
mals with CNS depression. Repeated doses of activated
phine derivatives include codeine and the more potent
charcoal function to decrease the biological half-life of
hydromorphone, both Schedule II drugs. Heroin is a
barbiturates. A cathartic such as sorbitol can be added,
Schedule I morphine derivative.
but magnesium-containing cathartics such as magnesium
Synthetic opioids include butorphanol and tramadol,
sulfate (Epsom salt) should be avoided because they
which are Schedule VI drugs, and methadone, propoxy-
can enhance CNS depression. IV lipid emulsion has
phene, meperidine, and pentazocine, all Schedule III
been used for lipid soluble barbiturates to decrease
drugs. Oxycodone and hydrocodone are prescription
the bioavailability and minimize clinical signs (Bischoff
synthetic opioids classified as Schedule II. Fentanyl is
et al., 2011).
formulated into injectable solutions, slow-dissolving
Monitoring and control of body temperature is essen-
sticks for oral transmucosal absorption, and patches that
tial to prevent ventricular fibrillation and decrease the
release doses of 25, 50, 75 or 100 μg/h for transdermal
duration of the clinical signs. Intubation and assisted ven-
absorption. Fentanyl is about 80 times more potent than
tilation are required when marked respiratory suppression
morphine (Branson and Gross, 2001). Other potent syn-
is noted. Fluid therapy is necessary in some cases to
thetic opioids are alfentanil, sufentanil citrate, and etor-
maintain cardiac and renal function. Alkaline diuresis has
phine HCl, which is 10,000 times as potent as morphine
been used to increase the rate of excretion of some barbi-
and used in wildlife capture. These potent drugs are
turates but is ineffective with short-acting barbiturates.
Because tissue partitioning attenuates the effects of barbi- classified in Schedule II. Desomorphine is a schedule I
turates, it is possible for the patient to relapse as the drug drug.
repartitions from the tissues back into plasma. Certain The morphine derivative heroin is one of the most
abused opioids, and use is increasing because of increased
drugs are contraindicated in the barbiturate overdose
availability and relatively low cost (Dumonceaux, 1995;
patient. Dextrose, fructose, lactate, pyruvate and gluta-
Anonymous, 2011). A survey of US high-school students
mate can increase partitioning of barbiturates into the
found that 2.5% had used heroin, though another survey
CNS. Epinephrine and isoproterenol cause reanesthetiza-
stated that only about 1% had used heroin in the past
tion after thiopental exposure. Sulfonamides, salicylates,
year, and up to 25% said it was accessible to them
and doxycycline increase bioavailability of barbiturates
(Latimer and Zur, 2010). A white to dark brown powder,
by displacing them from plasma proteins.
heroin often contains additives such as sugar, starch, pow-
Many laboratories can analyze samples such as urine,
dered milk, quinine, or strychnine. Heroin was tradition-
blood products, or tissues for barbiturates. Common tech-
ally injected, but insufflation (snorting) and smoking are
niques include TLC and GC/MS. In one study, over-the-
becoming more popular. Heroin is also available as a
counter drug testing kits for urine were successful in bar-
black sticky substance termed “black tar heroin,” which is
biturate detection in canine urine, though these kits are
dissolved, diluted, and injected.
not always reliable (Teitler, 2009).
Oxycodone, sold as OxyContin, Percocet, and in a
generic form, is commonly used recreationally. A recent
survey found that 9% of US high-school seniors had used
Opioids
prescription opioids recreationally (Latimer and Zur,
Opium is produced from Papaver somniferum, a poppy, 2010). Pills are time-released but may be crushed and
and its use was recorded in the Ebers Papyrus, one of the insufflated or injected in solution. Hydrocodone, sold
oldest known medical texts, dated around 1500 BC. under various trade names and in formulations with acet-
The unripe seed capsule is incised after the petals have aminophen (Vicodin) is also commonly sold on the illegal
fallen. Material that exudes from the capsule is dried, drug market. Fentanyl can be produced in clandestine lab-
collected, and dried further to produce opium. Powdered oratories and is used intravenously.
opium is 75% inert ingredients, about 10% morphine, Desomorphine is a synthetic morphine derivative that
which is the major active alkaloid, 0.5% codeine, and is easily manufactured and considered 10 times as potent