Insulin preparations: First of all let me give you a mild introduction. Insulin was first discovered by Banting and Best in 1921. From then on, the porcine and bovine pancreas served as a major sources of the hormone. Insulin is secreted by Beta cells of pancreas as Proinsulin initially where it is digested to release the hormone of interest. It is comprised of 51 Amino acids and consists of two chains interlinked by disulphide bond. Chain A is composed of 21 AA while Chain B is composed of 30 AA. The interlinking disulphide bond occurs at A7 and B7 & between A and B19. Various formulations of Insulin are developed taking the pharmacodynamic and pharmacokinetic aspects under consideration. Here are few preparations I listed out: REGULAR AND RAPID SOLUBLE PREPARATIONS: Initially, Insulin is prepared under acidic conditions but this process led to an unstable product with loss of potency. Then efforts are made to improvise the product to best serve people. The chemical stability is enhanced by preparing under neutral conditions as Zinc stabilized solutions. INTERMEDIATE ACTING INSULIN PREPARATIONS: The intermediate acting insulin preparations are: NPH and Lente. These preparations show their effects by achieving the "dissolution of precipitated/crystalline form of insulin". NPH is Neutral Pratamine Hagedorn named after the inventor HC Hagedorn. THE DISSOLUTION PROCESS IS THE RATE LIMITING STEP FOR THE BIOAVAILABILITY OF INTERMEDIATE ACTING AND LONG ACTING INSULIN. LONG ACTING INSULIN PREPARATIONS: Ultralente and Lantus(r) are the Long acting Insuling preparations. The former was introduced in 1950s while the latter is new analog and is commercially available. These preparations are characterized by "slow and relatively constant release of insulin solid" via subcutaneous tissue. The rate of absorption into bloodstream is relatively low in Long acting Insulin Preparations. Reference: Pharmaceutical Biotechnology - An Introduction for Pharmacists and Pharmaceutical Scientists, Edited by Daan J A Crommelin and Robert D Sindelar, 2nd Edition, Routledge Taylor and Francis Group, Page No: 231- 237 THIS BLOG IS FREE OF PLAGIARISM.