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In Short Supply

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On January 26, 2010 the Centers for Disease Control and Prevention (CDC) issued a notice about shortages of the antiviral drug acyclovir in the U.S., noting some regional variability in availability of the drug. A long-standing treatment option for genital herpes (and other conditions such as shingles), acyclovir is a generic drug valued by many patients for its effectiveness and low cost.

How could this happen?
The Food & Drug Administration (FDA) attributes this acyclovir shortage to a combination of factors, specifically citing increased demand for the drug and manufacturing delays. These are but two factors that can contribute to drug shortages, according Lynda S. Tyler, Pharm. D., FASHP. In her presentation “Understanding Drug & Managing Shortages,” developed for a 2002 meeting of the American Society of Health-System Pharmacists, Tyler explains both predictable and unpredictable reasons for drug shortages.

Among the predictable factors include decisions on the part of manufacturers that may limit supply. For example, Tyler explains that manufacturers may temporarily or permanently reduce production of a specific product as they make decisions to reallocate resources within the company. Additionally, production of a particular drug may be decreased or halted by a manufacturer due to such factors as possible safety concerns or a lack of consumer demand. A sudden surge in consumer demand, due to perhaps a disease outbreak or new unlabeled use of a drug, can also contribute to shortages.

Tyler also cites market factors that can play a role. Among these factors is the release of a generic version of a drug. As Tyler notes, “Sometimes, the addition of a generic product to the market may precipitate a decrease in the manufacturing of the innovator product and create a temporary reduction in the supply of a particular medication.” The potential for profit also leads what Tyler terms “grey” market vendors to take advantage of the basic economic principle of supply and demand. Vendors can create artificial shortages by purchasing large quantities of a particular drug and withholding these from market. They can then resell the drug at an inflated price.

Not all causes of drug shortages are predictable or controllable, of course. Tyler cites such unpredictable factors such as natural disasters that can affect production at manufacturing facilities, shortages of raw materials, and voluntary product recalls, particularly when one company manufactures the majority of a particular product.

According to Tyler, statistically 27% of shortages are unexplained, 28% are due to manufacturing problems, 20% product discontinuation, 10% supply and demand issues, 8% raw material problems, and 7% regulatory problems.

Acyclovir manufacturer GlaxoSmithKline attributes their shortage to increased demand, according to the FDA’s drug shortage website. For their part, Teva Pharmaceuticals cites manufacturing delays.

If you are unable to get a prescription at your normal pharmacy, try calling other pharmacies or seeing if a different dose is available. For example, if you normally take 400 mg twice a day, you could see if 200 mg tabs are available and take two of those twice a day. You can also look on the internet for legitimate pharmacies and ask your provider to fax the prescription to a new location.

So what are those currently taking acyclovir to do? Look online for alternative treatments?
No. ASHA president Lynn Barclay understands that patients who take acyclovir for genital herpes and reside in affected regions have few options other than more costly medications. “Acyclovir is a safe, effective, inexpensive treatment option both for those with short- and long-term prescriptions. We’re optimistic the supply issue will be resolved soon, but we understand how difficult this must be for patients who need therapy for herpes but are temporarily unable to access their regular prescription.”

Barclay notes that while legitimate over-the-counter products are available for oral herpes outbreaks (cold sores) exist, there are no FDA-approved medications available without a prescription to treat genital herpes. “Beware ‘miracle cures,’ as there are many non-regulated items sold online that claim to reduce or eliminate herpes outbreaks,” she says. “We know such products might be tempting for someone who has trouble refilling a prescription, but we stress in the strongest possible terms not to use anything to treat genital herpes without first checking with your healthcare provider or pharmacist.”

Therefore, those concerned with managing outbreaks while unable to get acyclovir, may want to speak with their healthcare provider about exploring the alternative of using a different medication as treatment. Other antivirals approved to treat genital herpes include valacyclovir (available under the brand name Valtrex® and generic) and famciclovir (marketed as Famvir®).

Please continue to check the FDA website for any updates.

For more information on drug shortages, see Understanding & Managing Drug Shortages, Proceedings of a breakfast symposium held during the 37th ASHP Midyear Clinical Meeting, available from American Society of Health-System Pharmacists, presented by Linda S. Tyler, Pharm.D., FASHP and Scott M. Mark, Pharm.D., M.S.


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