this question has been coming up lately on all of these lists, and was answered in lay language earlier today.
this is from joel, whom many of us know, owner of the FIV-HealthScience list. it is significantly more technical, but gives us all the info we should need to make our own decisions--or, at least, to ask informed questions. MC ---------- Forwarded message ---------- From: joel kehler <joelkeh...@yahoo.com> Date: Wed, Jun 10, 2009 at 9:54 AM Subject: Re: question about interferon! To: twelvehousec...@gmail.com Hi MC, The quick answer is that everyone is guessing on this (freezing) issue because no one seems to have tested dilute interferon to see if potency is left intact. One of the sources cited below indicates that it is possible to assay dilute interferon for biological activity. However, since his study did not use frozen interferon, it sheds no light on the effect of freezing We (i.e., within FIV-HS) found a number of views expressed by researchers and pharmacists on the issues of freezing and on the issue of the viability of refrigerated solution. 1. "The interferon is supplied as a concentrated stock solution containing 3 million IU/vial. we recommend diluting the entire contents of the stock vial into a 1 L sterile IV fluid bag (sterile saline solution) and mixing the contents well. This results in 1000ml of solution containing 3000IU/ml. *This solution can then be divided into aliquots of 1 and 10 ml and frozen. * Depending on the volume of working solution required, either 1 ml of the solution may be added to 100ml of sterile saline solution, or 10 ml of the solution may be added to i-L of an IV solution bag to give 100 or 1000 ml,respectively, of interferon at concentration dosage of 30IU/ml. The stock solution (3 million IU) or concentrated solution (1000 IU/ml) can be stored apparently for years without losing activity. Once reconstituted at working concentration at 30 IU/ml, the solutyion may be stored in a refrigerator (4 C) for several months without losing activity. *The activity of dilute interferon solutions (30 IU/ml) after frozen storage is not known, therefore we do not recommend freezing unused portions of 30 IU/ml concentration of interferon.*" --Practical Guidelines for Using low-dose orally administered huIFN-a in cats infected with FeLV, JAVMA, vol 199, No. 10, Nov 15, 1991. 2. Dr. Massimo Amadori (the Italian researcher who headed a research team that produced the study cited below) said (in a private correspondence) *it should never be frozen*, but preserved with bovine serum albumin, which practically requires a pharmacist. The following comes from his study and reflects protocols of an earlier researcher, Meager: "hIFN-a was diluted to 50 IU mL 1 in phosphate buffered saline (PBS) pH 7.2 supplemented with bovine serum albumin (2 mg mL 1) (PBS–BSA), aseptically filtered through 0.22 mm absolute cartridges and aliquoted into sterile 50 mL bottles provided with injection stoppers and aluminium seals. The bottles containing the diluted hIFN-a were stored at 4C throughout the study.* Under these conditions, diluted hIFN-a was shown to be stable for at least 12 months. The biological activity of hIFN-a was determined in the cytopathic effect (cpe) inhibition assay using bovine MDBK cells with vesicular stomatitis virus* (Meager, 1987)." -- Low-dose interferon-a treatment for feline immunodeficiency virus infection. E. Pedretti a, B. Passeri b, M. Amadori a,*, P. Isola c, P. Di Pede d, A. Telera d, R. Vescovini d, F. Quintavalla b, M. Pistello. epublished early in Veterinary Immunology and Immunopathology xxx (2005) xxx–xxx. 3. In a private communication, Dr Joe Cummins, the researcher who "invented" the application of oral low-dose interferon, said *it could be frozen and thawed as needed.* However, he doesn’t recommend keeping the dosage level dilution at refrigerated temperatures for more than a week-- not because it will lose its biological properties but because it risks contamination by bacteria or mold. (He recommended checking your working bottle / syringe to make sure it remains unclouded. If clouded, discard it.) 4. Island Pharmacy describes their handling of the dilution thus: "To prepare a 30unit/ml oral solution, IPS first dilutes the Roferon in 1000ml of sterile saline. *This first dilution is reported to be stable indefinitely when frozen.* A second dilution reduces the concentration to 30 units per ml. * This second dilution should not be frozen, but must be stored in the refrigerator.* IPS labels the 30unit/ml dilution with a 90-day expiration date, thus a 50ml quantity is sufficient for 90 days when using the 7 days on, 7 days off schedule. ---- www.islandpharmacy.com/site/1420401/page/769212 5. "I called this pharmacy to ask why they say the interferon at 30 units /ml should not be frozen.* I spoke with pharmacist Dave. He explained that there are a lot of questions about this but basically that domestic freezers dont get cold enough and fluctuate in temprature.* And that crystals could destroy the molecules. (A point we have covered before I think)." --Report of group member You can conclude what you want from these views. Except for Cummins, no one seems to validate freezing the final dilution. Feel free to post whatever you want of the preceding in your forum... -- Spay & Neuter Your Neighbors! Maybe That'll Make The Difference.... MaryChristine Special-Needs Coordinator, Purebred Cat Breed Rescue (www.purebredcats.org) Member, SCAT (Special-Cat Action Team) _______________________________________________ Felvtalk mailing list Felvtalk@felineleukemia.org http://felineleukemia.org/mailman/listinfo/felvtalk_felineleukemia.org
