Excipients of concern in the package inserts of human medicines prescribed in veterinary pharmacotherapy: frequency and implications for animal health

The therapeutic arsenal for veterinary pharmacotherapy includes both medicines for exclusive veterinary use and human medicines prescribed off-label for animals. Unlike medicines for exclusive veterinary use, the package inserts of human medicines detail the qualitative composition of the excipients in these products. Some excipients may cause adverse reactions in specific animal populations, necessitating that healthcare professionals identify and avoid administering medicines containing these excipients to susceptible animals. In this study, we analyzed 120 package inserts for human medicines prescribed for animals and, identified 14 excipients of concern for this population: 10 in liquid products, 6 in semi-solid products, and 5 in solid products. The identified excipients include ethyl alcohol, benzyl alcohol, benzalkonium chloride, mannitol, sodium metabisulfite, sodium lauryl sulfate, propylene glycol, polyethylene glycol, polysorbate, and ethoxylated castor oil. Although off-label use of human medicines in veterinary practice is permitted, the study suggests that regulatory agencies and professional councils should raise awareness among veterinary prescribers and pharmacists regarding these excipients. This unprecedented study highlights the urgent need to address this issue, aiming to encourage research on excipient safety in animal populations and strengthen veterinary pharmacovigilance services.

Impact of concerning excipients on animal safety: insights for veterinary pharmacotherapy and regulatory considerations

OBJECTIVES

Veterinarians and pharmacists are familiar with the efficacy and safety aspects attributed to active pharmaceutical ingredients included in medicines, but they are rarely concerned with the safety of excipients present in medicines. Although generally recognized as safe, excipients are not chemically inert and may produce adverse events in certain animal populations. This review aims to present excipients of concern to these populations and highlight their relevance for rational veterinary pharmacotherapy.

EVIDENCE ACQUISITION

A comprehensive review of the literature about the existence of adverse reactions in animals caused by pharmaceutical excipients was carried out based on an exploratory study. An overview of the correct conditions of use and safety of these excipients has also been provided, with information about their function, the proportion in which they are included in the different pharmaceutical dosage forms and the usual routes of administration.

RESULTS

We identified 18 excipients considered of concern due to their potential to cause harm to the health of specific animal populations: bentonite, benzalkonium chloride, benzoic acid, benzyl alcohol, ethanol, lactose, mannitol, mineral oil, monosodium glutamate, polyethylene glycol, polysorbate, propylene glycol, sodium benzoate, sodium carboxymethylcellulose, sodium lauryl sulfate, sulfites, polyoxyethylene castor oil derivatives, and xylitol. Among the 135 manuscripts listed, only 24 referred to studies in which the substances were correctly evaluated as excipients.

CONCLUSIONS

Based on the information presented in this review, the authors hope to draw the attention of professionals involved in veterinary pharmacotherapy to the existence of excipients of concern in medicines. This information contributes to rational veterinary pharmacotherapy and supports veterinary pharmacovigilance actions. We hope to shed light on the subject and encourage studies and new manuscripts that address the safety of pharmaceutical excipients to the animal population.

Clinical use of plasma lactate concentration. Part 1: Physiology, pathophysiology, and measurement

OBJECTIVE

To review the current literature with respect to the physiology, pathophysiology, and measurement of lactate.

DATA SOURCES

Data were sourced from veterinary and human clinical trials, retrospective studies, experimental studies, and review articles. Articles were retrieved without date restrictions and were sourced primarily via PubMed, Scopus, and CAB Abstracts as well as by manual selection.

HUMAN AND VETERINARY DATA SYNTHESIS

Lactate is an important energy storage molecule, the production of which preserves cellular energy production and mitigates the acidosis from ATP hydrolysis. Although the most common cause of hyperlactatemia is inadequate tissue oxygen delivery, hyperlactatemia can, and does occur in the face of apparently adequate oxygen supply. At a cellular level, the pathogenesis of hyperlactatemia varies widely depending on the underlying cause. Microcirculatory dysfunction, mitochondrial dysfunction, and epinephrine-mediated stimulation of Na⁺ -K⁺ -ATPase pumps are likely important contributors to hyperlactatemia in critically ill patients. Ultimately, hyperlactatemia is a marker of altered cellular bioenergetics.

CONCLUSION

The etiology of hyperlactatemia is complex and multifactorial. Understanding the relevant pathophysiology is helpful when characterizing hyperlactatemia in clinical patients.

Clearance of plasma ivermectin with single pass lipid dialysis in 2 dogs

OBJECTIVE

To describe the use of single pass lipid dialysis (SPLD) for treatment of ivermectin toxicosis in 2 Australian Shepherd dogs with the ABCB1-1Δ gene mutation.

CASE SERIES SUMMARY

Two Australian Shepherd dogs were presented for treatment of ivermectin toxicosis. Dogs were initially treated with intravenous lipid emulsion and supportive care, without improvement of clinical signs. They both developed respiratory paralysis and required mechanical ventilation. In order to increase the clearance of circulating ivermectin, SPLD was performed using dialysate containing 5% lipid. Blood samples were obtained immediately before and after dialysis and analyzed for serum ivermectin concentration. Ivermectin reduction ratio was calculated at 29% and 39% for each dog, respectively. When compared to intrinsic total body ivermectin clearance, only the second dog had a relative improvement of plasma clearance following SPLD. Both dogs were confirmed to be homozygous for ABCB1-1Δ gene mutations. Both dogs remained ventilator dependent for several days and ultimately made a full recovery.

NEW OR UNIQUE INFORMATION PROVIDED

SPLD may be an adjunctive detoxification strategy for highly lipophilic toxins such as ivermectin.

Update: Clinical Use of Plasma Lactate

Lactate is an essential, versatile metabolic fuel in cellular bioenergetics. In human emergency and critical care, lactate is used as a biomarker and therapeutic endpoint and evidence is growing in veterinary medicine supporting its clinical utility. Lactate production is a protective response providing ongoing cellular energy during tissue hypoperfusion or hypoxia and mitigating acidosis. Hence, hyperlactatemia is closely associated with disease severity but it is an epiphenomenon as the body attempts to protect itself. This article reviews lactate biochemistry, kinetics, pathophysiology, some practical aspects of measuring lactate, as well as its use in diagnosis, prognosis, and monitoring.

Stability of osmolality in previously frozen canine serum and urine samples

BACKGROUND

The measurement of osmolality is of interest in several clinical conditions and has been investigated in multiple veterinary studies. However, the stability of osmolality over time in frozen canine serum and urine has not been established.

OBJECTIVES

The purpose of this study was to determine the stability of osmolality in canine serum and urine stored frozen at -20°C and -80°C up to 90 days, and to assess the effect of storage temperature on osmolality measurement.

METHODS

Serum and urine samples collected from 5 healthy Greyhound dogs were aliquoted and stored at -20°C and -80°C until measurement. Osmolality, assessed by freezing-point depression, was measured at 0, 7, 14, 30, and 90 days of storage.

RESULTS

For both serum and urine, osmolality at day 7 was not statistically different from day 0, but osmolality at days 14, 30, and 90 was significantly lower than at day 0. There was no significant effect of storage temperature on serum osmolality. However, the osmolality of urine samples stored at -20°C was slightly, but significantly lower than the osmolality of those stored at -80°C.

CONCLUSIONS

Osmolality measurement in the serum and urine of healthy dogs appears to be stable for at least 7 days in frozen samples. The small changes observed after day 7 are unlikely to be relevant for individual patients, but could have implications in research study protocols.

Use of Lactate in Small Animal Clinical Practice

Lactate is a product of anaerobic metabolism. Lactate concentration in blood is used clinically as an indicator of tissue hypoperfusion and hypoxia to determine disease severity, assess response to therapy, and predict outcome. This article reviews lactate physiology, sample collection and processing, and interpretation of lactate concentration in clinical practice.

A toxicological review of the propylene glycols

The toxicological profiles of monopropylene glycol (MPG), dipropylene glycol (DPG), tripropylene glycol (TPG) and polypropylene glycols (PPG; including tetra-rich oligomers) are collectively reviewed, and assessed considering regulatory toxicology endpoints. The review confirms a rich data set for these compounds, covering all of the major toxicological endpoints of interest. The metabolism of these compounds share common pathways, and a consistent profile of toxicity is observed. The common metabolism provides scientific justification for adopting a read-across approach to describing expected hazard potential from data gaps that may exist for specific oligomers. None of the glycols reviewed presented evidence of carcinogenic, mutagenic or reproductive/developmental toxicity potential to humans. The pathologies reported in some animal studies either occurred at doses that exceeded experimental guidelines, or involved mechanisms that are likely irrelevant to human physiology and therefore are not pertinent to the exposures experienced by consumers or workers. At very high chronic doses, MPG causes a transient, slight decrease in hemoglobin in dogs and at somewhat lower doses causes Heinz bodies to form in cats in the absence of any clinical signs of anemia. Some evidence for rare, idiosyncratic skin reactions exists for MPG. However, the larger data set indicates that these compounds have low sensitization potential in animal studies, and therefore are unlikely to represent human allergens. The existing safety evaluations of the FDA, USEPA, NTP and ATSDR for these compounds are consistent and point to the conclusion that the propylene glycols present a very low risk to human health.

Death by caffeine: presumptive malicious poisoning of a dog by incorporation in ground meat

BACKGROUND

A 4-year-old, 37 kg, male German shepherd developed hyperthermia, tachycardia, and agitation following consumption of ground meat found in the backyard of its owner. When presented to a veterinary clinic, plasma ethylene glycol (EG) testing was positive, and the dog was given ethanol and lactated Ringer's solution intravenously. Approximately 11 h postexposure the dog died.

DISCUSSION

Among tissues submitted for toxicological analysis, urine was negative for EG, ground meat was negative for certain drugs of abuse, and gastric contents were negative for zinc/aluminum phosphide and metaldehyde. Analysis of gastric contents by gas chromatography-mass spectrometry confirmed the presence of caffeine. Caffeine concentration in the ground meat was estimated at 1 %. Caffeine is a methylxanthine alkaloid with a reported canine oral median lethal dose (MLD(50)) of 140 mg/kg (range 120-200 mg/kg). A commercially available 200-mg tablet formulation of caffeine was considered to be a possible source but this was not confirmed. By conservative estimates, the dog would need to ingest approximately 500-550 g of the meat to reach the MLD(50). Acute intoxication affects the cardiovascular, pulmonary, neurologic, gastrointestinal, and metabolic systems. Although no tablet remnants were observed in the bait, tablets could have been crushed and/or dissolved. Other potential caffeine sources include guarana, brewed and concentrated coffee, and caffeine-containing beverages. Based on the history, clinical signs, and the detection of caffeine in the gastric contents and meat, a presumptive diagnosis of malicious caffeine poisoning was made. A suggested treatment regimen for caffeine intoxication in dogs is described. While few cases of accidental ingestion of caffeine by dogs have been described, the intentional use of a concentrated caffeine source to cause mortality in a dog has not been previously reported.

Management of urinary tract emergencies in small animals

This article focuses on some of the most commonly seen urinary tract emergencies in dogs and cats, with emphasis on basic pathophysiology, diagnosis, and emergency management of these cases.