Case 11

It has been an hour since Rintu received the initial dose of methocarbamol, and the tremors are starting to return and his temperature is rising (102.3 F [39 C]).

The owners have returned with the topical flea product used on Rintu, and you confirm that it indeed contains permethrin.You administer a second dose of methocarbamol, but this time his tremors do not abate, and, after an hour, Rintu’s temperature is 103.5 F (39.7 C).

Because you have been diligently keeping up with your journal reading and attending veterinary continuing education conferences, you know that there has been success in a small number of veterinary patients using intravenous lipid emulsion (ILE) therapy for treating certain lipophilic drug toxicoses. Intravenous lipid emulsion is typically used in veterinary medicine as the lipid component of total or partial parenteral nutrition recipes; however, studies in people have demonstrated its utility in reversing the toxic effects of drug overdoses.

Successful use of ILE therapy has been reported anecdotally in veterinary patients for ivermectin, moxidectin, permethrin, loperamide, baclofen, bupropion, marijuana, and sertraline toxicoses.

There is uncertainty about how ILE therapy works in patients with toxicoses, but the emulsion may provide a “lipid sink” compartment that lipophilic agents migrate to, which accelerates their elimination. One lipid emulsion commonly used for this purpose is Intralipid (Baxter Pharmaceuticals), which is formulated as soybean oil in water and stabilized by an egg phospholipid emulsifier. The soybean oil provides a source of the essential fatty acids linolenate and linoleate. The lipid emulsion is iso-osmolar to blood and is isotonic, so it can be administered through peripheral catheters.

The lipid emulsion provides about 50% of the daily resting energy requirements in dogs and cats, so some nutritional support is also provided.

QUESTION 5

ILE therapy has been used successfully in people and in a limited number of animals to treat several lipophilic drug toxicoses. Among the following compounds, which are lipophilic and which are hydrophilic?

a) Lidocaine

-Lipophilic

-Hydrophilic

b) Caffeine

-Lipophilic

-Hydrophilic

c) Phenobarbital

-Lipophilic

-Hydrophilic

d) Marijuana

-Lipophilic

-Hydrophilic

e) Lead

-Lipophilic

-Hydrophilic

f) Ivermectin

-Lipophilic

-Hydrophilic

<< Back | Next Step >>