As pet ownership continues to rise, the demand for effective veterinary medications grows alongside it. One of the questions often asked by pharmaceutical companies is whether human drugs can be repurposed for use in animals. This approach, while tempting due to its potential cost and time savings, requires careful consideration of numerous factors to ensure the safety and efficacy of the drugs for our furry friends. In this blog post, we’ll explore the key aspects of repurposing human drugs for pets, based on insights from a recent live stream by Lab for POS.
What is Drug Repurposing?
Drug repurposing involves adapting existing medications, typically developed for humans, for use in animals. While this might seem straightforward, the process is far from simple. Animals have different physiological, metabolic, and genetic makeups compared to humans, which means that a drug that works well in humans might not have the same effect in animals—or could even be harmful.
Why is Drug Repurposing Important?
The pet medicine market has been expanding rapidly, driven by higher standards of care for pets, increased pet ownership, and longer lifespans for both humans and their animal companions. As a result, the expenditure on veterinary medications is increasing, making the repurposing of human drugs an attractive option for pharmaceutical companies.
Market Potential
In 2023, the sales of repurposed drugs showed promising growth, with pet drug sales forecasted to increase by 8.3% annually, outpacing the growth of human drug sales. This trend highlights the growing importance of the veterinary pharmaceutical market and the potential benefits of drug repurposing.
Key Considerations in Drug Repurposing
1. ADMET Parameters
ADMET stands for Absorption, Distribution, Metabolism, Excretion, and Toxicity. These are critical factors in determining how a drug behaves in the body. Different species have varying ADMET profiles, which can significantly impact the drug’s efficacy and safety.
For example, the enzymes responsible for drug clearance in dogs differ from those in humans. In dogs, cytochrome P450 enzymes such as CYP3A12 and CYP3A98 play a significant role, whereas in humans, CYP3A4 and CYP3A5 are more prominent. This difference means that a drug metabolized safely in humans might accumulate to toxic levels in dogs, or vice versa.
2. Species-Specific Drug Effects
Different animals have unique physiological responses to drugs. A drug used to treat a particular condition in humans might be used for a completely different purpose in animals. For instance, Gabapentin, a drug used to manage pain and seizures in humans, is also used for these purposes in dogs. However, in cats, Gabapentin is primarily used to alleviate anxiety, particularly during veterinary visits. These differences underscore the importance of understanding species-specific drug effects before repurposing a medication.
3. Dosage Variability
The appropriate dosage of a drug can vary widely between species, due to differences in metabolism and drug clearance rates. For example, the dosage of Gabapentin for dogs ranges from 50 mg/kg, while for cats, it varies from 5 to 30 mg/kg. This variability highlights the need for precise dosing information to avoid underdosing or overdosing, both of which can have serious consequences.
4. Drug Formulation Differences
The formulation of a drug—such as the additives and excipients used—can also affect its safety in animals. Some ingredients safe for human consumption can be toxic to animals. For example, human formulations of Gabapentin often contain xylitol, a sweetener that is highly toxic to dogs and should be avoided in veterinary patients. This emphasizes the need to carefully evaluate and possibly modify drug formulations when repurposing them for pets.
5. Target Expression Levels
The expression levels of drug targets can differ significantly between species, leading to variations in drug efficacy. For example, Clopidogrel, an antiplatelet medication used to prevent strokes and heart attacks in humans, targets the P2Y12 receptor on platelets. However, this receptor is expressed at much lower levels in cats and dogs, reducing the drug’s effectiveness in these animals. Understanding these differences is crucial in determining whether a human drug can be successfully repurposed for veterinary use.
Conclusion
While repurposing human drugs for pets offers significant potential, it requires careful consideration of species-specific differences in drug metabolism, physiology, dosage, formulation, and target expression. Pharmaceutical companies interested in this approach must conduct thorough research and testing to ensure the safety and efficacy of these drugs for animal use.
If you’re a pharmaceutical company considering drug repurposing or seeking biospecimens for your research, feel free to contact us at Lab for POS. We are committed to advancing the field of veterinary medicine and helping reduce the reliance on animal testing in both human and animal health research.
Thank you for reading, and stay tuned for more insights on the latest developments in veterinary pharmacology!
