Abstract
Animal testing is mandatory in drug testing and is the gold standard for toxicity and efficacy evaluations. This situation is expected to change in the future as the 3Rs principle, which stands for the replacement, reduction, and refinement of the use of animals in science, is reinforced by many countries. On the other hand, technologies for alternatives to animal testing have increased. The need to develop and use alternatives depends on the complexity of the research topic and also on the extent to which the currently used animal models can mimic human physiology and/or exposure. The lung morphology and physiology of commonly used animal species differs from that of human lungs, and the realistic inhalation exposure of animals is challenging. In vitro and in silico methods can assess important aspects of the in vivo effects, namely particle deposition, dissolution, action at, and permeation through, the respiratory barrier, and pharmacokinetics. This review discusses the limitations of animal models and exposure systems and proposes in vitro and in silico techniques that could, when used together, reduce or even replace animal testing in inhalation testing in the future.
Highlights
Strategies for Animal Studies in Animals are used in science worldwide, but the actual numbers are often unknown and difficult to compare between countries because reporting varies considerably (https://speakingofresearch.com/facts/animal-research-statistics/).According to the most recent report of the European Commission, more than 60% of the animals used in 2017 were mice, 12% were rats, 13% were fish, and 6% were birds.Dogs, cats, and non-human primates accounted for 0.3% of the total
This review highlights the limitations of animal testing with respect to the specific differences in the anatomy, physiology, and pathology of the respiratory systems of laboratory animals commonly used in pulmonary research and discusses the status of in vitro and in silico techniques as alternatives to the efficacy and toxicity testing of drugs for oral inhalation and inhaled toxicants
The models were generated by disruption of the cystic fibrosis transmembrane conductance regulator (CFTR) gene or the introduction of the ∆F508 CFTR mutation
Summary
Strategies for Animal Studies in Animals are used in science worldwide, but the actual numbers are often unknown and difficult to compare between countries because reporting varies considerably A study published a decade ago, reported average costs of 1.5 billion for a marketed drug [2]. The most expensive and longest part in the development is the clinical phase of the testing and it is, important that the development of non-promising drugs is stopped in the preclinical phase. This phase includes target identification and dose finding in cellular screening, the pharmacokinetic profile, the pharmacodynamic profile, the bioavailability, and safety studies (acute and chronic toxicity testing, reproductive toxicity and teratogenicity, mutagenicity and carcinogenicity, immunotoxicity, and local tolerance) of animals.
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