Gadolinium-based contrast agents, which are used mainly for magnetic resonance imaging and angiography, were first introduced partly because of the discovery in the 1990’s that iodine-based contrast agents could cause nephrotoxicity and acute renal failure. Some recent reports have suggested, however, that gadolinium-based agents may also be nephrotoxic.1 One patient who developed acute renal failure after use of gadolinium-based contrast had a renal biopsy that showed acute tubular injury.2Moreover, after exposure to gadolinium-based contrast, some patients with severe renal insufficiency,...

A reader expressed disappointment that our recent listing of “Some Warfarin Drug Interactions”1 did not include acetaminophen. Perhaps it should have. Acetaminophen can increase the anticoagulant effect of warfarin, particularly with continued use, but it does so inconsistently. The mechanism of this interaction has not been established, but may be related to an acetaminophen metabolite inhibiting vitamin K-epoxide reductase, the target for warfarin’s anticoagulant effect.2Patient susceptibility varies, possibly on a genetic basis; occasional use of acetaminophen generally has little or...

The nicotine receptor partial agonist varenicline (Chantix - Pfizer) appears to be the most effective drug available to treat tobacco dependence, but the FDA has added a warning to the package insert about neuropsychiatric symptoms and exacerbations of preexisting psychiatric illness associated with its use. Agitation, hostility, depressed mood, suicidal ideation and suicidal behavior have been reported as postmarketing adverse events in patients who took varenicline and stopped smoking and in those who took the drug and continued to smoke.

The American Heart Association (AHA) recently published a statement saying that it would be reasonable to obtain an electrocardiogram (ECG) in children being evaluated for stimulant drug therapy for attention deficit hyperactivity disorder (ADHD). A subsequent news release in conjunction with the American Academy of Pediatrics provided a clarification, saying that it would be reasonable to consider obtaining an ECG in such children.

The FDA has approved the marketing of a new device for delivering lidocaine to the skin of children undergoing a venipuncture or intravenous (IV) line placement. Zingo (Anesiva) is a powder intradermal injection system.

Melamine present in infant formula and other milk products has been associated with widespread illness and some deaths among infants in China. It was also identified in pet food sold in North America after a large number of pets became ill and some died. In both the infants and the pets, renal injury appeared to be the cause.1Melamine (C3H6N6) is a heterocyclic compound, two-thirds nitrogen by weight, that is slightly soluble in water. When combined with formaldehyde, it forms melamine resin, which has a wide variety of industrial applications including the manufacturing of kitchenware,...

Inhaled drugs for asthma are available in the US mainly in pressurized metered-dose inhalers (MDIs), which require a propellant, and dry powder inhalers, which do not. The chlorofluorocarbon (CFC) propellants in MDIs are being replaced by hydrofluoroalkane (HFA) propellants for environmental reasons: CFCs contribute to the depletion of the ozone layer. December 31, 2008 will be the last day that albuterol MDIs using CFC propellants can be sold in the US. The FDA is expected to announce a termination date for other CFC-containing products in the near future.Three HFA albuterol inhalers and one...

The FDA has added a boxed warning to fluoroquinolone package inserts about tendon injuries that may occur as a result of their use. Tendinitis or tendon rupture may occur rarely with systemic use of any fluoroquinolone, either while the drug is being taken or for up to several months afterwards.Fluoroquinolone-related tendon injury is rare; estimates for its incidence in the general population range from 0.14% to 0.4%. The risk is higher for patients >60 years old and for those taking corticosteroids. For patients with organ transplants, the incidence may be as high as 15%.1 A case-control...

A recent article in the New England Journal of Medicine confirms something that others, including The Medical Letter (Treat Guidel Med Lett 2008; 6:23), have been saying for years: no particular combination of protein, carbohydrate and fat in the diet offers any advantage in losing weight. This randomized 2-year trial followed 800 overweight and obese subjects on low fat/average protein, low fat/high protein, high fat/average protein, and high fat/high protein diets. Carbohydrate intake varied from 35% (in the high fat/high protein diet) to 65% (in the low fat/average protein diet). All...

The FDA has announced that it will lower the age for over-the-counter access to the emergency contraceptive Plan B1 from 18 to 17 years old. In a randomized, controlled trial, the two 0.75-mg levonorgestrel tablets in Plan B, taken 12 hours apart beginning within 72 hours after unprotected intercourse, decreased the overall pregnancy rate to 1.1% (11/976) of women who requested emergency contraception.2 The sooner the drug is taken after coitus, the more effective it is. Nausea and vomiting can occur with Plan B. Fetal malformations have not been associated with pregnancies that occurred...