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Norvir Advisory

Eugene Sun, MD, Explains Reasons for New Temperature Guidelines

Exerpt from Interview with Eugene Sun, MD, by Charles Farthing, MD

Farthing: There have been some concerns that temperatures may be an issue in the formation of crystals and that was the reason for the recent change in the label indication for storage temperature. Would you comment on these concerns?

Sun: Temperature is an important factor in the balance between the dissolved and the solid -- or crystalline -- state of not only Norvir, but all chemical substances. The alteration in recommended storage conditions was undertaken to safeguard against the possibility of crystallization following the discovery of the new ritonavir crystal form.

Farthing: Could you explain the new storage temperature guidelines and the data that supports these guidelines? (See Question 4 on Abbott's Frequently Asked Questions for information about new temperature recommendations.)

Sun: Norvir liquid should be stored at room temperature -- between 68º and 77º fahrenheit (20º - 25º celsius) -- and shaken well before using. The reason we changed storage to room temperature was really as a precautionary measure. We think there is the potential, though small, for crystals to form if the liquid remains refrigerated, while it is exceedingly unlikely that they would form if the liquid is kept within the recommended temperature range. Shaking the liquid before each dose means that any crystals that could form would dissolve back into the liquid, ensuring the liquid retains its potency for every dose.

Farthing: What about greater extremes in temperature? Is there data on the consequences of storage of Norvir liquid at higher temperatures? What happens if there is a "brown out" and/or electricity is lost and someone's home temperature shoots up to 100 degrees-plus for several hours?

Sun: Temperature extremes should be avoided if possible. As with all drugs, maintaining optimal storage conditions ensures that they retain their potency. However, it is important to realize that it is not an on-off situation, but a gradation. Short excursions outside the recommended range are less consequential than prolonged ones -- but precisely how consequential, we can’t say with any certainty.

Posted 9/3/98

Notice: This is an IAPAC initiative that is under the sole direction of the IAPAC Norvir Advisory Committee. Contents of the Norvir Advisory section of the IAPAC Web site are subject to the approval of the chair of the advisory committee and will reflect the recommendations of the committee members. Abbott Laboratories has no input in the content of the Norvir Advisory section of the IAPAC Web site.