pharmacokinetic, pharmacodynamic and physiological differences, and distinct
market drivers for drug classes used in companion and food-producing animals.
This chapter reviews selected commercialised and research-based parenteral and
non-parenteral veterinary drug delivery technologies in selected domestic species.
Emphasis is also placed on the impact of endogenous drug transporters on drug
distribution characteristics in different species. In vitro models used to investigate
carrier-dependent transport are reviewed. Species-specific expression of transpor-
ters in several tissues can account for inter-animal or inter-species pharmacoki-
netic variability, lack of predictability of drug efficacy, and potential drug–drug
interactions.
KeywordsABC transportersEpithelial drug transportIntraruminal devices
Ivermectin formulationP-glycoprotein effluxTopical deliveryVeterinary drug
deliveryVeterinary drug interactions
1 Introduction to Veterinary Drug Delivery: Comparison
with Drug Delivery in Human Medicine
Three of the six significant developments recently predicted to be of paramount
importance in the generation of safer and more efficacious veterinary drugs in the
next 20 years include drug delivery, nanotechnology and pharmacogenomics
(Riviere 2007 , this text, chapter, “New Technologies for Application to Veterinary
Therapeutics”). Optimism with respect to future developments in drug delivery
reflects recent successes in human medicine with new multi-functional polymer
chemistry, assisted transdermal patch technology and novel particulate formula-
tions all moving into the clinical development phase. It would be a mistake,
however, to presume that there is a high degree of leveraging between human and
veterinary drug delivery technologies. Progress in veterinary drug delivery fol-
lowed developments made with species-specific delivery devices in veterinary
medicine over the past 50 years. While pharmaceutical formulation expertise is
the paramount skill-set required in both human and veterinary drug delivery, the
latter has had a greater focus on device-led engineering science driven by physio-
logical parameters in a particular species.
In addition to the primary objective of delivering optimal concentrations of
pharmaceuticals to their site(s) of action over a required period, there are many
drivers for the application of drug delivery technology to veterinary therapeutics
(Table 1 ). In production animals, delivery technologies must be mass market and
inexpensive. They are primarily restricted to antibacterial drugs, anti-parasiticides,
trace elements, vitamins, and growth promoters (non-EU). For example, one-time
bolus injections, drenches, or balling-gun administrations are designed to reduce
costs and minimise risks of injury to animals and staff. In contrast, in companion
animals, the cost issues to maintain the additional “family member” are similar to
80 D.J. Brayden et al.