Do proton pump inhibitors cause fractures?
Recent evidence suggests that long-term use of proton pump inhibitors (PPIs) increases the risk of fractures, and the FDA has recently published a safety announcement stating that health care providers should be aware of this risk. Postmenopausal females and patients older than 50 years who are treated with PPIs for longer than 1 year appear to be at the greatest risk. This is a class effect, and some studies have shown a dose-dependent relationship, with higher doses translating to increased fracture risk.
The mechanism behind the increased risk of fractures is unknown, although some have speculated that hypochloria reduces calcium absorption. Another proposed mechanism is that PPIs indirectly affect bone metabolism, resulting in a decreased bone mineral density, but this theory is controversial.
Regardless of the mechanism, PAs should identify the risks and benefits of PPIs for each patient before prescribing them. Use the lowest effective dose for the shortest possible duration, and ensure that your patients receive the recommended daily intake of calcium and vitamin D. Recommend vitamin supplements if needed, and monitor bone mineral density in appropriate patients. If supplemental calcium is required, calcium citrate may be better absorbed than calcium carbonate, as the latter requires an acidic environment for enhanced absorption. It is unclear at this time if H2-receptor antagonists (H2RAs) increase fracture risk. However, long-term treatment with H2RAs seems to be associated with a lower risk of fracture than long-term therapy with PPIs.1
Are people with iodine or shellfish allergies also allergic to IV contrast?
Heath care professionals have propagated this medical myth for years, despite evidence to the contrary. Shellfish allergy was originally thought to be caused by the high iodine content in seafood, and a cross-allergy to iodinated radiocontrast agents was surmised. However, this has been shown to be false. Shellfish allergy is due to specific proteins found in the food, not a reaction to the iodine content.
In fact, iodine by itself is not an allergen.
People who have food allergies (milk, eggs, or chocolate), drug allergies (such as penicillin), asthma, and allergic rhinitis are all at a higher risk of having an allergic reaction to contrast.2 The same is true for people with seafood allergies. The bottom line is that people who are allergic to one thing are at an increased risk of being allergic to something else. Atopic persons have a propensity to be hyperallergic. However, no cross allergy exists between shellfish and contrast media, and having a shellfish allergy is not a contraindication to radiocontrast dye.
Adverse reactions to contrast media are not immune-mediated by IgE, and the term nonimmunologic anaphylaxis (previously referred to as anaphylactoid reactions) has been coined to describe serious reactions to contrast. Nonimmunologic anaphylaxis to radiocontrast can occur on first exposure to the agent. Anaphylactic reactions, however, are immune mediated by IgE and require a previous exposure to the antigen. True anaphylactic reactions to contrast are rare. The etiology of nonimmunologic anaphylaxis is thought to result from the osmolarity of the contrast media, with high-osmolality agents conferring a greater risk of reaction. To reduce the incidence of serious adverse reactions to contrast media, particularly in atopic patients, low osmolality contrast medias should be used. Patients should be monitored for at least 20 minutes after the administration of radiocontrast.
The decision to premedicate "at risk" patients is often institution- or provider-specific. However, the American College of Radiology emphasizes that no clinical studies have unequivocally demonstrated prevention of contrast reactions by using short-term IV corticosteroid premedication.3 If steroids are used, they should be given orally 4 to 6 hours prior to the administration of the contrast agent. If this is not possible, it is reasonable to omit the corticosteroid and use only H1 blockers. JAAPA
Larissa DeDea, PharmD, BCPS, PA-C, completed a pharmacy practice residency at Gallup Indian Medical Center, Gallup, New Mexico, and has worked on the Navajo Reservation as a pharmacist for the Public Health Service. In addition to being board certifi ed in pharmacotherapy, she is a recent graduate of the Yale University PA Program.
REFERENCES
1. Roux C, Briot K, Gossec L, et al. Increase in vertebral fracture risk in postmenopausal women using omeprazole. Calcif Tissue Int. 2009;84(1):13-19.
2. Schabelman E, Witting M. The relationship of radiocontrast, iodine, and seafood allergies: a medical myth exposed [published online ahead of print December 31, 2009]. J Emerg Med.
3. Manual on Contrast Media v7. American College of Radiology Web site. http://www.acr.org/SecondaryMainMenuCategories/quality_safety/contrast_manual.aspx. Accessed July 19, 2010.