2003D-0206 - Draft Guidance for Industry on Exocrine Pancreatic Insufficiency Drug Products--Submitting New Drug Application; Availability
FDA Comment Number : EC4
Submitter : Dr. Tibor Sipos Date & Time: 07/07/2004 05:07:29
Organization : Digestive Care, Inc.
Drug Industry
Category :
Issue Areas/Comments
PART 3 OF 10
DOCKET NO. 2003D-0206 (2003N-0205)

Pancrelipase drug substance is available in two different lipase potencies from Scientific Protein Labs (SPL). The two drug substances are: ?Pancreatic Enzyme Concentrate (PEC)? with approximately 50 USP units of lipase activity, and ?Pancreatic Enzyme Concentrate High Lipase (PEC-HL)? with approximately 100 USP units of lipase activity.

Pancrelipase is isolated from the pancreatic glands of pigs by a series of extraction and purification steps. Pancrelipase contains proteins, carbohydrates, nucleic acids, lipids, minerals, and complex tissue components. The proteins which possess biological activity are further defined as enzymes, e.g. lipase, protease, amylase, etc.; or as hormones, e.g. glucagons, insulin, etc. Most of the enzymes are secreted as zymogens (inactive precursors) which need to be activated by limited proteolysis to active enzymes. The conversion of zymogens to active enzymes proceeds through a highly complex sequence of enzymatic steps. These steps give rise to multi-components of pancrelipase products with variable enzyme ratios and enzyme potencies, e.g. ratios of 1:4:4 to 1:8:5 for PEC and 1:3:3 to 1:5:3 for PEC-HL (lipase:amylase:protease) and enzymatic activities of 40 to 70 USP units/mg of lipase for PEC and 80-120 USP units/mg of lipase for PEC-HL with activities of 180 ? 460 USP units/mg of amylase and 120-400 USP units/mg of protease, respectively.

Foremost, the characterization and purity of the drug substance for classical biologicals are daunting tasks. Use of methods described in the proposed guidelines would yield dozens of peaks or bands and it would be extremely difficult or impossible to completely determine which of these peaks or bands are part of the active component and which do not contribute to its overall activity. Guidelines Q7A for API already recognizes that impurity profiles from animal tissue origin is an unnecessary step (Section XI B. p. 18).

Furthermore, both PEC and PEC-HL contain water-soluble and water-insoluble components. The proportion of water-soluble components of PEC is approximately 70% and of PEC-HL is approximately 80-85 %. Lipase activity is distributed between the water-soluble and the water- insoluble portions in a proportion of 45% to 55% in PEC, and 65% to 35% in PEC-HL, respectively. Because lipase activity is present as water- soluble enzymes and also as water-insoluble enzymes, the potency of pancrelipase needs to be assayed as a dispersion in the assay media. Hence, demonstration of catalytic activity via lipase potency is the absolute criteria for product activity and identity. Identification and characterization of pancrelipase needs to be based on catalytic activity; e.g. able to hydrolyze lipid substrate (triglycerides) into free fatty acids and monoacyl glycerol.

The proposed guidelines for the identification of pancrelipase suggest the use of the following methods: HPLC, SDS-PAGE electrophoresis, isoelectric-focusing and other advanced biochemical techniques. These proposed methods are excellent research tools but have limited use in the
identification of the pancrelipase drug substance. We would also like to point out that the employment of any one of these techniques is only suitable for the fingerprint analysis of the water-soluble fraction of pancrelipase, while completely ignoring the water-insoluble fraction with a substantial number of biological active components. When the soluble fraction of pancrelipase is subjected to isoelectric focusing in ampholine containing gel in one dimension, one can identify at least 27 clearly separated and Coomassie brilliant blue, R-250 stained bands. If the electrophoretic separation continues into the second dimension, the initial 27 bands further separate into multiple bands of extreme complexities.