Cinchona bark, deadly nightshade leaf, dandelion root, yew bark – are only some examples of the sources of important compounds used in pharmacotherapy. Medicine based on natural sources has been enjoying growing popularity amongst the general public for years, but not all natural compounds used this way are isolated exclusively from plants. Pharmaceuticals of an animal origin also come from a natural source and are a part of a wide assortment of medicines of natural origin. They can be a product of animal metabolism, be isolated from non-animal materials such as cocoons and nests, but also from animal parts. When you hear these terms for the first time, your mind might jump to ideas such as using parts of animals in a pill, for example a monkey leg or an elephant tusk. However, this is most definitely not the case so it may be best to read what this is really about.
Beginnings
The use of animals for pharmacotherapy, as one of the earliest and best-known methods, was bloodletting using leeches (Hirudo medicinalis). Although this practice was discarded over time, leeches have remained an interesting research topic. Thus, it was discovered that leech saliva contains compound called lepirudin, which prevents the coagulation of the host’s blood which the leeches feed on. Following the example of this compound, hirudin was developed, which also serves as an anticoagulant and thrombin inhibitor. In Mayan culture, crushed ants, specifically the Pseudomyrmex family, were used as a toothache therapy, while the bite of live ants was used for joint pain relief. Some of the earliest compounds used for pharmacotherapeutic purposes were heparin, insulin, and various pituitary hormones. These compounds, although their isolation seems rather rudimentary today, have saved numerous lives, and have served as a paragon for the development of new compounds.
Development
Following the discovery of insulin in 1920, patients with diabetes were treated with insulin isolated from the porcine or bovine pancreas. Heparin was originally extracted from dog liver (hence the name heparin, Greek hepar-liver). Later it was developed and adapted for widespread use and is still used today for a number of coronary and cardiovascular diseases. In contrast to heparin, protamine sulfate, which has the opposite effect of heparin, was isolated from salmon sperm and later produced using recombinant DNA technology. In the 1970s, captopril, which was approved by the FDA in 1981, became the first ACE inhibitor and was isolated from the venom of a Brazilian snake (Bothrops jararaca).
Also from the same source, but a different snake, the dwarf rattlesnake (Sistrurus miliarius barbouri), eptifibatide, an inhibitor of platelet glycoprotein receptor IIb / IIIa, was isolated and is used to prevent thrombosis.
Thyroid tablets, called Armour thyroid, are a preparation that has been isolated from porcine thyroid glands and is one of the best-known drugs of such origin. It is used in the treatment of hypothyroidism as a supplement or replacement therapy. Gelatin, a product used in almost every household, is widely used in the pharmaceutical industry for the production of capsules, and can be of porcine or bovine origin.
Marine sources
In addition to sources from various terrestrial animals, one of the most important cytostatics for the treatment of various types of leukemia has been isolated from a sea sponge. Cytarabine (from the name of the original compound that is isolated cytosine arabinoside) was extracted from the Caribbean sponge (Cryptotheca crypta) and approved in 1969 by the FDA. Also extracted from a sea sponge, this time from the species Halichondria okadai, is halichondrin B which also acts as a cytostatic.
A new era of animal therapy
Compounds isolated from animal sources have helped develop a wide range of modern drugs used all around the planet. Today, animals are helping us more and more in a completely different way. Animal assisted therapy (AAT) and helper animals are becoming more common in people with various chronic diseases and conditions. Dogs, cats, birds, horses, and many other animals, in addition to the role of our best friends, have also found themselves as faithful helpers in dealing with various situations.
Translator: Josipa Radeljak
Literature sources
http://alphaomegaalpha.org/pharos/PDFs/2015-1-Bozoghlanian-Butteri.pdf, pristupljeno 30.4.2020.
Armour thyroid, https://www.rxlist.com/armour-thyroid-drug.htm#description, pristupljeno 30.4.2020.
Cancer drug discovery: unravelling the mysteries of halichondrin, https://www.pharmaceutical-technology.com/, pristupljeno 7.7.2020.
Buljan Flander G et al. Benefits of Therapy Dogs in Therapy and Diagnostics of Patients with Psychosocial and Health Difficulties. Soc. psihijat. 2018, 46, 413-425.