Page 390 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

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VetBooks.ir Chapter 21

Toxicity of Over-the-Counter Drugs

Karyn Bischoff

INTRODUCTION hypermanganesemia (Khan et al., 2010; Borchers et al.,
2014). Toxicologically important minerals, such as iron,
The topic of over-the-counter (OTC) drugs is complicated,
and important vitamins, such as vitamin D, are addressed
encompassing a large number of products, many contain-
in other chapters. Stimulants and diet pills often contain
ing multiple active ingredients. Products are available for
methylxanthines, such as caffeine, which are also
oral, topical, intraocular, intranasal, and intrarectal admin-
addressed in appropriate chapters, or sympathomimetic
istration, although most veterinary exposures are through
amines, which are discussed later with decongestants.
ingestion. These products are readily available in many
homes. Toxicosis can result when animals are medicated
by well-intentioned animal owners or even veterinarians,
SUSPECTED OTC DRUG REACTIONS
or accidental exposure, in which case, the amount of medi-
cation ingested may not be known. Response to a given Obtaining a thorough history is of great importance when
drug may be species-specific or different between indivi- dealing with suspect OTC drug-related problems (Talcott,
duals of the same species. Idiosyncratic and allergic reac- 2006). Animal owners do not always volunteer critical
tions to drugs must also be considered, although reports in information. Well-intentioned pet owners sometimes
domestic animals are rare (Papich, 1990; Brumbaugh, administer OTC drugs to treat perceived symptoms in
2001; Meani and Nixon, 2015; Stewart et al., 2016). their pets (Papich, 1990; Jones et al., 1992; Villar et al.,
Approximately one-quarter of the calls to human poi- 1998; Roder, 2004a; Sellon, 2006). Veterinarians some-
son control centers in 1990 dealt with OTC drugs times share the blame for inappropriate dosing. Chronic
(Murphy, 1994; Villar et al., 1998). More than 16% of analgesic administration to treat orthopedic problems is a
calls to the American Society for the Prevention of particular hazard in many species of domestic animals.
Cruelty to Animals’ Animal Poison Control Center Accidental ingestions can occur when drugs are
(ASPCA-NAPCC) in 2016 were for OTC medications improperly stored. Careful assessment of the history can
(http://aspcapro.org/resource/shelter-health-poison-control/ be challenging, but is critical, and unexpected circum-
top-10-toxins-2016). It is estimated that there are more stances can arise. For example, severe clinical signs
than 300,000 OTC drug formulations available, with prompted euthanasia in a kitten that was later discovered
approximately 700 active ingredients in various combina- to have been playing with an empty acetaminophen tablet
tions (Papich, 1990); only a small fraction will be container (Allen, 2003). In another example, appropriate
addressed in this chapter. treatment was delayed when an owner failed to report
Important classes of drugs that will be addressed ingestion of analgesics containing acetaminophen and
include analgesics, cold, flu, and allergy medications, and codeine upon presenting their puppy to the veterinarian
drugs used to treat gastrointestinal symptoms. Nutritional for anxious behavior and cyanosis (Stewart et al., 2016).
supplements, for the most part, will not be addressed If an adverse reaction to an OTC drug is suspected,
here, although a few herbal preparations (ma huang and administration of the drug should be immediately discon-
guarana) are discussed. Supplements containing cyano- tinued. The owner should be instructed to bring the drug
bacteria (blue-green algae) have been associated with container to the veterinarian as a source of information
microcystin toxicosis in dogs, which is addressed else- on the active ingredients, indications for use, and manu-
where in this text (Bautista et al., 2015). There have been facturer identification, telephone number, and address.
several reports of joint supplement overdose associated Many manufacturers have information on treatment and
with acute liver failure in dogs, likely due to the prognosis, and, in the United States, will use the

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