IS IV ERYTHROMYCIN 
EFFECTIVE FOR GI MOTILITY?


Erythromycin is a macrolide antibiotic that is used off label as a prokinetic agent. It increases gastric emptying by activating motilin receptors in the upper GI tract. Motilin is an endogenous hormone that enhances peristalsis and accelerates gastric emptying. Erythromycin activates motilin receptors when it is administered both orally and intravenously. The dosage is 3 mg/kg (up to 250 mg) IV every 8 hours. 


Pitfalls of using erythromycin to enhance gastric emptying include the development of antibiotic resistance, pseudomembranous colitis, multiple drug interactions, and increased risk of sudden cardiac death due to prolongation of the QT interval. This risk is increased in patients taking cytochrome P450 inhibitors. Additionally, the prokinetic effects of erythromycin diminish after continued use, likely due to motilin receptor downregulation. Therefore, erythromycin is primarily used in the acute setting to enhance gastric emptying as an alternative or adjunct to other therapies. 


WHAT SUNSCREEN IS BEST?


The Skin Cancer Foundation recommends using a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15. The product should be reapplied every 2 hours and immediately after swimming or sweating. Starting in 2012, the FDA is requiring significant labeling changes designed to assist consumers in choosing an appropriate product.1


Sunscreens will no longer be able to state waterproof or sweat proof on the label. Once wet, all sunscreens begin to lose effectiveness. Only the term water resistant will be allowed combined with the duration of water resistance. If this information is not on the label, the product is not water resistant. Additionally, manufacturers may no longer identify a product as a sunblock. 


Sunburn is primarily caused by ultraviolet B (UVB) radiation; however, ultraviolet A (UVA) radiation can also result in sunburn, premature aging, and skin cancer. The FDA is using the term broad-spectrum to denote products that have met the FDA standard for protection against both UVA and UVB rays. 


Another proposed change in sunscreen labeling involves the sun protection factor. The SPF is a measure of how long it takes the skin to burn when sunscreen is applied compared to not using sunscreen. A product with an SPF of 10 means that it will take 10 times longer for the skin to redden, if the sunscreen is applied properly. There is no compelling evidence that an SPF greater than 50 provides better protection than an SPF of 50. Therefore, the FDA is proposing that SPF values higher than 50 be labeled as SPF 50+. 


Recommend SPF 15 broad-spectrum sunscreen for daily use. Consider a water resistant product with an SPF of 30 for people with outdoor occupations or prolonged sun exposure. People who are extremely sensitive to the sun, such as those with lupus, may benefit from SPF 50+ products, as may patients taking medications known to cause photosensitivity. Emphasize the importance of reapplying sunscreen, wearing appropriate clothing, and avoiding sun exposure between 10 am and 2 pm if possible. Advise patients that although products with an SPF value between 2 and 14 may prevent sunburn, only broad-spectrum sunscreens with an SPF of 15 or higher are indicated to reduce the risk of skin cancer and effects of early skin aging.


HOW SHOULD ENOXAPARIN BE DOSED TO PREVENT DVT IN OBESE PATIENTS?

There is controversy over how to dose enoxaparin for DVT prophylaxis in obese patients. While fixed-dose enoxaparin is most commonly used (40 mg SC daily), this dosage may not be adequate for patients with a body mass index (BMI) greater than 35 kg/m2 (morbid, or class II, obesity).

Deep venous thrombosis prophylaxis in bariatric surgery patients is well-studied, and enoxaparin 40 mg SC every 12 hours is proven to be safe and effective. In patients undergoing Roux-en-Y gastric bypass who have a BMI greater than 50 kg/m2, enoxaparin 60 mg SC every 12 hours may also be used. It is less clear how to dose enoxaparin in obese medical patients. A recent review article recommends increasing prophylactic doses of enoxaparin by 30% in patients with a BMI of 40 kg/m2 or greater.2 Another small study evaluated enoxaparin 0.5 mg/kg SC daily in patients with a BMI of 35 kg/m2 or greater.3 There were no symptomatic DVTs or bleeding episodes. Another strategy is to use enoxaparin 0.5 mg/kg divided in two daily doses.


More studies are needed to evaluate outcomes associated with different dosing strategies in obese medical patients. Most current studies support weight-based dosing over fixed-dose enoxaparin in morbidly obese patients. JAAPA


Larissa DeDea, PharmD, BCPS, PA-C, is a clinical pharmacist with Northern Arizona Healthcare, Flagstaff, Arizona. In addition to being board certified in pharmacotherapy, she is a graduate of the Yale University PA program.

REFERENCES


1. FDA sheds light on sunscreens. http://www.fda.gov/downloads/ForConsumers/ConsumerUpdates/UCM258910.pdf. Accessed July 20, 2011.


2. Nutescu EA, et al. Low-molecular-weight heparins in renal impairment and obesity. Ann Pharmacother. 2009;43(6):
1064-1083. 


3. Rondina MT, Wheeler M, Rodgers GM, et al. Weight-based dosing of enoxaparin for VTE prophylaxis in morbidly obese, medically-ill patients. Thromb Res. 2010;125(3):220-223.