Abstract
Plastic materials are widely used in medical items such as solution containers, infusion sets, transfer tubing, devices, processing equipment and systems, filters, and the like. Components in medical items can leach out of such items when they are contacted by a therapeutic product or product-related solution. Stearic acid and stearate salts are commonly present in medical and food packaging, either as plastic additives, processing aids, or contaminants, and their leaching from plastics is well documented. With a pKa in the range of 5.1 to 5.6 and limited aqueous solubility (log Po/w greater than 8), the leaching of stearic acid (and its related metal salts) into pharmaceutical products is expected to be strongly dependent on the product's pH and polarity. In order to establish and understand the leaching behavior of stearate-containing materials, three compounds (stearic acid, calcium stearate, and zinc stearate) and four polymeric materials containing these compounds were contacted with aqueous buffers in the pH range of 2.5 to 11. The leached levels of calcium, zinc, stearate, palmitate, and total organic carbon (TOC) were measured in the resulting solutions and are reported. For materials containing only stearic acid or salts themselves, the extraction of these entities is pH-dependent. At low pH, the cation counter-ions of the stearate salts are extracted from the plastic materials by a process that can loosely be termed ion exchange. At intermediate pH, little or no extraction of the stearates occurs. At high pH, the stearates are extracted from the materials to a very limited extent due to the solubility of the acid and/or salts in the extraction medium.
- © PDA, Inc. 2010
PDA members receive access to all articles published in the current year and previous volume year. Institutional subscribers received access to all content. Log in below to receive access to this article if you are either of these.
If you are neither or you are a PDA member trying to access an article outside of your membership license, then you must purchase access to this article (below). If you do not have a username or password for JPST, you will be required to create an account prior to purchasing.
Full issue PDFs are for PDA members only.
Note to pda.org users
The PDA and PDA bookstore websites (www.pda.org and www.pda.org/bookstore) are separate websites from the PDA JPST website. When you first join PDA, your initial UserID and Password are sent to HighWirePress to create your PDA JPST account. Subsequent UserrID and Password changes required at the PDA websites will not pass on to PDA JPST and vice versa. If you forget your PDA JPST UserID and/or Password, you can request help to retrieve UserID and reset Password below.
