Sources of drugs are of various types and these drugs can be obtained from various sources such as: 1. Animal, e.g. antitoxic sera, gonadotrophines, heparin, insulin and thyroid extract. 2. Drugs produced by genetic engineering (i.e. by DNA recombinant technology), e.g. human growth hormone and human insulin. 3. Mineral, e.g. zinc, aluminum hydroxide, liquid paraffin, [...]