Drugs animal testing

Drug Animal tests, Phase Phase II Phase III NDA Ongoing... 

True zwitterionic compounds are rare among drugs. The oral absorption of truly zwitterionic compounds is poor unless the compound is a substrate for an absorptive biological transporter as in an a-amino acid which is a substrate for the PepTl nutrient transporter. The aqueous solubility of a true zwitterionic compound will be at a minimum at the isoelectric point which unfortunately for many compounds happens close to the neutral pH at which oral absorphon occurs. Species extrapolation predicting oral absorphon and pk/pD from preclinical animal tests to man are difficult for zwitterions. 

Preclinical drug development also involves animal testing [61]. Data from one rodent species and one nonrodent species are usually collected to determine the absorption, metabolism, and toxicity characteristics of the compound. Both short-term (2 weeks to 3 months) and long-term (up to several years) studies are done. The long-term studies are particularly useful for... 

One potential risk that formulators run when using cosolvents as drug solubilizers is the possibility of vehicle toxicity. Each cosolvent is characterized by an acceptable concentration range, which cannot be exceeded without incurring biological damage. To avoid the requirement for in vivo testing, several in vitro models have been advanced to evaluate the relative safety of cosolvent excipients. The most useful in vitro procedure follows the hemolysis of red blood cells, which has been correlated with in vivo animal tests [87,88]. 

The costs of drug development increase as a drug progresses through the development pipeline. Preclinical development is the time when chemical compounds are tested in the laboratory to learn as much as possible about how medicines work "in a test tube." These types of experiments can be done with many compounds in a relatively short time and with relatively low cost. This is also the time that animal testing begins to see whether the chemical compounds are safe. These studies help scientists to determine how medicines will be dosed in humans. They are also important to understand whether any toxicity is related to the medicines. Toxicological tests are time... 

Techniques of Oral Absorption. There are three major techniques for oral delivery of drugs to test animals. The most common way is by gavage, which requires that the material be in a solution or suspension for delivery by tube to the stomach. Less common materials may be given as capsules (particularly to dogs) or in diet (for longer-term studies). Rarely, oral studies may also be done by inclusion of materials in drinking water. 

Inclusion in drinking water is rarely used for oral administration of human drugs to test animals, though it sees more frequent use for the study of environmental agents. 

In recent years, much attention and effort have been directed toward the search for non-whole-animal tests to predict ocular irritation by drugs and chemicals. A variety of in vitro assays, as well as nonexperimental approaches, have been proposed. These model systems run the gamut of responses observed in vivo using biological... 

Drug development is a long and cost-intensive business. Only after years of lead identification, chemical optimization, in vitro and animal testing can the first clinical trials be conducted. Unfortunately, many projects still fail in this late stage of development after a considerable amount of money has been spent. According to estimates, preapproval costs for a new drug exceed US 800 million [1]. 

Merck patented MDMA and MDA in 1914, but World Wars I and II sidetracked any further research on the drugs. Interest in the two drugs was revived in the 1950s by the U.S. military, but never went further than the animal testing stage. 

The drug must be subjected to laboratory and animal tests, which must indicate that it can be safely tested in humans. 

Drug Development Tests are performed on the lead compounds in test tubes (laboratory, in vitro) and on animals (in vivo) to check how they affect the biological systems. The tests, often called preclinical research activities. 

Clinical Trial Application (CTA) has to be submitted to Health Canada seeking permission to conduct clinical trials. The submission should include information regarding drug characteristics, test data, animal studies, and clinical protocol. A clinical trial may be stopped when either it is shown to be unsafe or dramatic benefits are obtained. The approval process may be fast-tracked if a drug is shown to have substantial benefits, such as for treatment of life-threatening or severely debilitating conditions. 

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