Sorption of Benzoic Acid, Sorbic Acid, Benzyl Alcohol, and Benzalkonium Chloride by Flexible Tubing

Abstract

Earlier studies using methylparaben, propylparaben, and several types of flexible tubing showed that the parabens are sorbed by a number of commonly used tubing. The sorption increased with increase in time of contact and the tubing surface area. The temperature and pH ranges tested did not affect sorption. Current studies evaluated other commonly used antimicrobial preservatives used in oral, parenteral, opthalmic, nasal, and other pharmaceutical products. These preservatives include benzoic acid, sorbic acid, benzyl alcohol, and benzalkonium chloride. Results show that all preservatives, except benzalkonium chloride, are sorbed by several types of flexible tubing. After 24 hr, some types of tubing sorbed over 40% of benzoic acid, benzyl alcohol, and about 30% of sorbic acid. Significant losses were observed within a few hours. No sorption of benzalkonium chloride occurred in the tubing tested. Three different types of fluoropolymer resin tubing, Teflon (flourinated ethylene propylene (FEP), Teflon perfluoroalkoxy) (PFA) and Teflon polytetrafluoroethylene (PTFE, NXT), fluoropolymer FEP laminated Tygon tubing, and Zelite do not sorb any of the preservatives. Silicone tubing shows the highest sorption of preservatives. After 120 hr, as much as 64% of the preservative is sorbed by some tubing. Detailed studies using silicone tubing show that the sorption increases with increase in surface area at 25 degrees C, and increasing the temperature to 40 degrees C shows little change in sorption. At the concentration range generally used in formulations, the concentration of the preservative has no significant effect on sorption. Refilling the tubing with fresh preservative solution after contact with preservative solution for 168 hr still causes extensive sorption of the preservative. Desorption studies indicate that the sorbed preservatives are desorbed in water to a limited extent over 120 hr. Results are important in situations where short or extended interruptions occur in the processing and filling of products. This can lead to decreased and variable results due to residence of the solution in the tubing.

Spalling and Sorption of Tubing for Peristaltic Pumps

“…These results were expected based on earlier reported studies using several different 10 ft lengths of tubing with these and other commonly used preservatives. [3,4] …”

“…[3,4] These earlier studies used 10 ft lengths of silicone, PVC, Teflon w , and other types of commonly used flexible tubing. Results showed that no sorption occurred with Teflon tubing while rapid losses were noted with silicone and PVC tubing.…”

“…The tubing appear to approach saturation in 24 -48 hr. On the basis of earlier studies, [3,4] this can be explained based on the finite area of tubing (80.4 in. 2 ) that was exposed to these preservatives.…”

Components of abstracts: Logical structure of scholarly abstracts in pharmacology, sociology, and linguistics and literature

“…Several new structural elements appeared to be necessary during the analysis (Lužar, 2005). Results appeared in different patterns, therefore three subcategories were formed: Rd (direct results): Report results, obtained in the study, presented in the paper [e.g., “As the depth profiling proceeded, the chlorine signal increased and the relative intensity of the phosphorous decreased” (Felton & Perry, 2002)]. Rn (indicated results): Do not report results, but only indicate the kind of results that can be expected in the paper [e.g., “A guide for stabilization of pharmaceuticals to oxidation is presented” (Waterman et al, 2002)]. Rp (previous results): Report results, obtained from a published study [e.g., “Earlier studies using methylparaben, propylparaben, and several types of flexible tubing showed that the parabens are sorbed by a number of commonly used tubing” (Bahal & Romansky, 2002)]. …”

“…Rp (previous results): Report results, obtained from a published study [e.g., “Earlier studies using methylparaben, propylparaben, and several types of flexible tubing showed that the parabens are sorbed by a number of commonly used tubing” (Bahal & Romansky, 2002)].…”