sponsor Organization that takes primary ownership and responsibility for a product, and usually will be the license holder. A sponsor may outsource testing, clinical trials, or manufacturing to other entities (CLO, CRO, CMO) but retains oversight of the program. The exact division of roles is specified in contracts and in the quality agreement, a key GMP document.

spray-drying Creation of a fine powder by passing a bulk or final drug formulation through a hot air stream to evaporate dispersed droplets; contrast with freeze-drying.

stability 1. Ability to maintain constant characteristics in the presence of forces that threaten to disturb them; resistance to change. Resistance to structural, chemical, and biological changes in composition caused by such factors as light, temperature, and storage (shelf) time. 2. A defined characteristic of a given product; stability profile means the types of chemical degradations, rates, and expected shelf life that characterize a product.

The round retroviruses infecting this tissue are easy to see in this photomicrograph.

starting material European term meaning raw materials used in cGMP manufacturing, but excluding components. (See component, active starting material, raw material)

statistical process control Monitoring and controlling a process using statistical analysis with the aim of managing variability at critical process control steps.

stereoisomer Any of a group of isomers in which atoms are linked in the same order but differ in their spatial arrangement.

sterile Absolutely free of any microbiological contamination; an absolute state that cannot be proven unless all of a material is consumed in the test. In practical terms, sterility assurance is demonstrated by showing that less than 1 in 10⁶ units may be contaminated. (See USP Sterility Test)

stoichiometry The study of proportional (quantitative) relationships between two or more substances during a chemical reaction.

strain A population of cells all descended from a single cell.

subcutaneous Referring to the layer of tissue (subcutis) directly underlying the cutis, which is mainly composed of adipose tissue. Subcutaneous (abbr: subq or sc) injections are given by injecting a fluid into the subcutis. It is relatively painless and an effective way to administer particular types of medication. Certain depot injections are a solid or oil-based medication which is administered subcutaneously where it releases its agent slowly over a period of weeks.

sublimation Passing directly from a solid to a vapor state without first melting into a liquid.

substrate Reactive material, the substance on which an enzyme acts.

substratum The solid surface on which a cell moves or on which cells grow.

sulfation The formation of sulfuric acid esters from alcohols or olefins (synthetic fibers, such as polypropylene).

sulfhydryl group Any compound of sulfur and another element, usually made by direct reaction of the elements.

supernatant Material floating on the surface of a liquid mixture (often the liquid component that has the lowest density); the overlying fluid layer that remains after precipitation of a solid component through centrifugation.

supercritical fluids Common gases, such as carbon dioxide, when under pressure contain a liquid form of the gas, and this liquid is useful in a variety of biotechnology applications.