Review of Cornea






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The Dating Game

When patients question the expiration dates of their medications, what should you tell them?
Alan G. Kabat, O.D., and Joseph Sowka, O.D.

8/15/2008

Mrs. Johnson, your long-time glaucoma patient, arrives for her three-month checkup. Pressures are well within the target range, and her visual fields look greatexcellent reliability and no evidence of progression. You assure her that the medication you prescribed is controlling her IOP. You stress the importance of continued compliance, ask her to return in three months for a comprehensive exam and begin to say goodbye.


At this point, she poses a question. Doctor, she says, I just found this bottle of drops in a suitcase that I used to visit my sister last summerI thought I had lost them! The bottle is almost full, but the date on the label says that it expired a few weeks ago. Can I still use it? I hate to throw medications away, because theyre so expensive and Im on a fixed income.


What do you tell her? This month, well examine the common, but controversial, issue of expiration dates.


When patients like Mrs. Johnson are concerned about the cost of their medications, how should you respond?


Setting the Date

All ophthalmic pharmaceutical agents carry a specific expiration datethe date beyond which the medication is no longer considered safe or recommended for use. Drugs may expire for a variety of reasons, but loss of potency and microbial contamination are presumably the most common. Also, some agents, such as 0.5% proparacaine, may oxidize and change color over time; while this does not necessarily impact the efficacy of the medication, it may be disconcerting to patients who find that the drops, which are normally clear, have turned yellow or brown.


So, for both diagnostic and therapeutic agents, most of us adhere pretty stringently to these labeled expiration dates. But, the question remains: How accurate and vital are they?


Since 1979, the FDA has required manufacturers to post expiration dates on all prescription and over-the-counter pharmaceutical agents for sale in the United States; however, these dates reflect only the period of time during which the company will guarantee the agents full safety and potency.1


Manufacturers determine this date by an entirely internal process, without strict FDA oversight. This lack of federal regulation has led some individualsconsumer advocates, specificallyto speculate that the published expiration dates on medications may be dictated more by marketing, turnover and revenue than true research data.2


Unfortunately, there is not much scientific evidence regarding expired medications. The most substantial prospective evaluation available was initiated by the U.S. military and the FDA in 1985. Stockpiles of old medications (within 12 to 18 months past expiration) were tested for potency, and most were found to be suitable for continued use.3 The FDA extended the official shelf life of 80% of the drugs tested by an average of 33 months.4 And, nearly half the expired medications studied in 1985 were found to still be viable when retested seven years later in 1992.3

 

Dating Safety

From a safety standpoint, very few medications are known to undergo dangerous transformation over time that would lead to substantial toxicity. The tetracyclines represent one category of drugs that has been linked to adverse events when used beyond the recommended expiration date. Numerous reports of acute renal disease have been documented, possibly due to an alteration in the drugs chemical structure that can initiate severe nephrotoxicity.5-7


Such a reaction is highly atypical, however. Most likely, a pharmaceutical preparation would simply lose potency, or topical agents would experience microbial contamination, if not used within the specified time frame. Most current ophthalmic preparations employ some form of preservative to enhance their shelf life and ensure sterility against common microbial pathogens, particularly after the bottle has been opened. The most commonly used of these agents is benzalkonium chloride (BAC or BAK), though other proprietary formulations have been employed for chronic-care medications, including Purite in Alphagan-P (brimonidine 0.1%, Allergan) and SofZia in Travatan-Z (travoprost 0.004%, Alcon).


Several topical antibiotic medications, such as Vigamox (moxifloxacin 0.5%, Alcon) and Iquix (levofloxacin 1.5%, Vistakon Pharmaceuticals), are self-preserved; they do not contain an added preservative, relying instead on higher antibiotic concentrations to impede microbial growth.


Still, other ophthalmic preparations are preservative-free. These medications, which include Restasis (cyclosporine 0.05%, Allergan) and Acular PF (ketorolac 0.5%, Allergan), are packaged in unit-dose vials that are sealed and intended for single use only.

 

Dating Indications

So, what can we tell Mrs. Johnson about her expired glaucoma medication? Can she safely use the drops, or should she throw them away? The evidencewhich is notably scantsuggests that it would be wasteful to discard pharmaceuticals that are only days or weeks past their expiration date.


We have advised patients that they can use drugs for up to a year (or more, in some cases) beyond their labeled expiration, though our recommendations depend on several factors:


What is the indication for the drug? Allergy preparations, such as Pataday (olopatadine 0.2%, Alcon) or Elestat (epinastine hydrochloride 0.05%, Allergan), are used primarily for subjective relief. So, they are easily evaluated for potency based upon their ability to alleviate patients symptoms. As long as they help relieve itching and redness, patients can likely use them with confidence. However, topical antibiotics and intraocular pressure-lowering agents, which are used in potentially sight-threatening disorders, require greater caution, depending on the severity or fragility of the disease state.


What is the condition of the bottle? Is it unopened and clean? Has it been exposed to extreme temperatures (such as in an
automobile glove box, attic or basement) or other adverse environments? The better maintained the product is, the less likely the risk of contamination or inactivation. Because most ophthalmic preparations are best suited for temperatures between 36 and 77F (2 to 25C), patients should be advised to store their unopened medication in a clean area of the refrigerator, as this will maintain and maximally extend the products viability.8


Is the product a preserved or non-preserved solution? Patients must take greater care with non-preserved products, since any breach of the original packaging may invite contamination. With a non-preserved product, consider such factors as the patients storage of it, if it is opened or sealed, or if it has been exposed to any extreme or adverse conditions.

 

In todays economy, the continuously rising cost of drugs makes managing patients with chronic ocular disorders challenging. While patients welfare must always be our greatest motivation, we can enhance compliance and build a lasting doctor-patient relationship by being realistic and sensitive to their economic concerns.

 

1. Newman BY. Drug expiration datesmeaningful? Optometry 2007 Apr;78(4):147-8.

2. Kramer TAM. Do medications really expire? Medscape Psychopharmacology Today. August 21, 2003. Available at: www.medscape.com/viewarticle/460159. (Accessed June 11, 2008.)

3. Extending the shelf life of critical chemical biological, nuclear and radiological (CBRN) medical materiel using the FDA/DOD shelf life extension program. Available at: https://slep.dmsbfda. army.mil/slep/slep_info_paper_JAN_2006.doc. (Accessed June 15, 2008.)

4. Cohen LP. Drugs frequently potent past expiration. The Wall Street Journal. 2000 March 29. Available at: www.wsj.com. (Accessed June 15, 2008.)

5. Frimpter GW, Timpanelli AE, Eisenmenger WJ, et al. Reversible Faconi syndrome caused by degraded tetracycline. JAMA 1963 Apr 13;184:111-3.

6. Montoliu J, Carrera M, Darnell A, Revert L. Lactic acidosis and Fanconis syndrome due to degraded tetracycline. Br Med J (Clin Res Ed) 1981 Dec 12;283(6306):1576-7.

7. Walker RG, Thomson NM, Dowling JP, Ogg CS. Minocycline-induced acute interstitial nephritis. Br Med J 1979 Feb 24; 1(6162):524.

8. Allergan, Inc. Lumigan package insert. June 2006.

Vol. No: 145:08Issue: 8/15/2008



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