encapsulation To enclose in a capsule, usually one made of a biodegradable polymer.
excipient A relatively inert substance, such as a syrup, that is added to a drug to make it easier to ship, store, or administer.
extractables Substances withdrawn (such as the medicinally active components of plant or animal tissue) by a physical or chemical process.
extrusion A process of forming rods, tubes, or other continuously formed pieces by pushing hot or cold semisoft solid material through
a die; also any process of pushing a substance through holes or a tube.
flash The material that oozes from the joint line of the mold cavity in plastics production.
folding A process in which a protein spontaneously forms into its correct, knotted tertiary structure that is held in place by chemical
bonds and by attractive forces between atoms.
formulation The method and process of selecting the components of a mixture; the product of such a process.
glass state The amorphous solid that contains the therapeutic protein in lyo-philization; any material that takes the shape of its container
and is formed by cooling a liquid until it is rigid but not crystallized.
glycoproteinA conjugated (joined together) protein in which the nonprotein group is a carbohydrate (such as sugar, starch, or cellulose).
half-life The time it takes for 50% of a drug or drug formulation given to a patient to be eliminated or disintegrated by natural
HEPA filtration Use of a high-efficiency particulate air filter to remove contaminants from a clean room.
high-pressure liquid chromatography (HPLC) Also high-performance liquid chromatography; a form of liquid chromatography for separating compounds dissolved in solution.
A liquid sample is forced at high pressure through a tube (column) that is packed tightly with chromatographic media (see
The BioPharm Guide to Separation and Purification, December 2000, for a detailed discussion of chromatographic methods and
hydrolysis Literally "cleaved by water," a reaction in which the chemical bond attaching an atom or group of atoms to the rest of a
molecule is severed, followed by attachment of a hydrogen atom at the same point.
hydrophilic Having an affinity for water; attracting, dissolving in, or absorbing water.
hydrophobicity The degree to which something repels water.
immunogen A substance that induces or elicits an immune response — that is, the body recognizes it as a foreign agent that must be
impurity A foreign agent or material either introduced as part of processing (such as buffers or salts added during chromatography)
or intrinsic to the nature of bioprocessing (such as product variants and cellular debris).
infusion Introducing a solution into the bloodstream or another solution; also refers to the solution itself, such as a drug formulation,
delivery Introduction of drugs through intact skin using the transfer of ions by applying a direct electric current.
isoelectric focusing An analytical technique that uses electrophoresis in a pH gradient to determine the isoelectric point (pI, see below) of
isoelectric point (pI) The pH at which a protein has no net charge. At a pH above the isoelectric point, a protein acts as a base. At a pH below
the isoelectric point, it acts as an acid. A solution of proteins or amino acids has its minimum conductivity and viscosity
isomerization Changing into an isomeric form (with the same chemical makeup but a different molecular structure — for proteins, therefore,
altering their activity).
isotonic Having the same osmotic pressure as blood serum, thus easily mixed with the blood.