Latex is a milky fluid that is obtained primarily from the rubber tree (Hevea brasiliensis). Hundreds of everyday products contain latex, including rubber bands, condoms, and the soles of shoes. Allergy to latex was first recognized in the late 1970s and has become a major concern in health care, given the significant number of people with latex allergies. In the health care setting, catheters, syringes, and gloves—most notably powdered gloves—have been a primary source of latex exposure and latex sensitization in both health care workers and patients1,2; it is estimated that 8% to 12% of health care workers are latex-sensitive. Exposure to latex protein antigens can cause an immediate hypersensitivity reaction. Since the early 1990s, FDA has received over 2000 adverse event reports describing allergic reactions to medical gloves that contain natural rubber latex, including five deaths.3
Once a patient is identified as latex-allergic, the pharmacist should determine the type and sensitivity of previous events by speaking with the patient and consulting with the patient’s prescriber and other health care team members. Reactions to latex exposure include irritant contact dermatitis, delayed hypersensitivity, and true type 1 latex hypersensitivity.4 Notably, only type 1 latex hypersensitivity is a true latex allergy, which can lead to life-threatening allergic reactions.
The general strategy in caring for patients who are latex-sensitive is to minimize their exposure. This can be achieved by eliminating the use of powdered latex gloves, latex-containing catheters, and other medical supplies used in the hospital environment. Nitrile, neoprene, isoprene, and other synthetic materials—acceptable for use in patients with latex sensitivity—are now commonly used in gloves and in other medical products. Not all medical products containing latex are available in latex-free versions; consequently, great care must be used to ensure that all products used by latex-sensitive patients are actually latex-free. Latex-free syringes and needles, however, are available from several manufacturers.
Latex in Compounding
Another common source of latex in parenteral medications and solutions is the vial stopper. Because of its excellent elasticity and durability, latex is used widely in stoppers. Multidose containers must withstand up to 10 punctures with a 21-gauge needle, for example, without allowing any liquid dye to penetrate the vial while under pressure; this is known as the self-sealing capacity test and is specified by USP Chapter <381> Elastomeric Closures for Injections. Synthetic butyl and isoprene rubber stoppers have been available since 1996, but these types of stoppers do not have the same self-sealing capacity as latex-based rubber stoppers.
Parenteral medications and solutions do not contain latex, but their containers or stoppers may. Because latex is water-soluble, any liquid medications packaged in vials with latex-containing stoppers may already contain the latex antigen in solution.5 For patients with a true type 1 latex allergy, it is important to source completely latex-free medications. Several fee-based Web site services exist that provide updated information on the latex content of pharmaceutical products.
For those patients who exhibit latex sensitivity, other approaches have been attempted in the past to reduce patient exposure, although not always with optimal results. For example, one medication preparation approach that has been used when preparing CSPs for latex-sensitive patients involves the physical removal of vial stoppers, also known as the pop-the-top method. This method is thought to prevent the transfer of latex antigens that occurs when the stopper is penetrated with a needle, and is based on a recommendation by the American Association of Nurse Anesthetists.6 One study evaluated the amount of latex allergen in solutions prepared using the traditional compounding method, in which the solution is removed from the vial with a needle through the dry rubber stopper, versus the pop-the-top method, in which the vial stopper is removed. The pop-the-top method creates an open container (a high-risk level condition) from which the solution can be removed without having to penetrate the stopper.7 There was essentially no difference in latex-allergen concentrations between the two compounding methods; however, it is important to note that one sample out of 20 (5%) prepared with the pop-the-top method grew bacteria, making this a more high-risk procedure to employ.
Another method,4,8 which offers advantages over the pop-the-top method, is referred to as the single-stick rule/observation approach, in which:
This method requires patient observation and monitoring from 30 minutes to two hours after each medication is administered. Johns Hopkins Hospital in Baltimore, Maryland, has employed this method successfully since 1999 without obvious patient issues.
Both the pop-the-top and single-stick rule/observation approaches are options for reducing a patient’s exposure to latex, but both are time-consuming, costly, and produce waste, as opened containers/vials are used once and then discarded. When caring for a patient with a true latex allergy who requires CSPs, the best method is to ensure all medications, solutions, and components are latex-free. Should that not be possible, the single-stick rule/observation approach is the preferred evidence-based method to provide safe and effective parenteral medication care.
Eric S. Kastango, MBA, RPh, FASHP, is the president, CEO, and owner of Clinical IQ LLC, a provider of customized process and educational strategies for the pharmaceutical, medical device, and health care industries. A member of USP’s Sterile Compounding Committee, he has practiced in the fields of both hospital and home care pharmacy since 1980.