Show #66, August 2007
Show #66, August 2007
|New Rapid Test for Malaria|
FDA recently cleared for marketing a rapid test for malaria, called Binax NOW, that can produce results in 15 minutes. Standard tests take far more time and require identifying parasites in a blood sample using microscopy.
The new product can differentiate Plasmodium falciparum, which is the most dangerous malaria parasite, from the other three Plasmodium species that can infect humans. Negative results with the Binax NOW test will still need to be confirmed using microscopy.
The test should help to minimize delays in treating patients who have malaria, and prevent unnecessary treatment in patients with malaria symptoms who do not have the disease. It could be an important diagnostic tool in parts of the world where malaria is endemic and where there are not enough qualified personnel to read microscopic smears. U.S. physicians will be able to use the test in returning travelers with signs or symptoms of malaria.
The Binax NOW test was compared to microscopy in over 4,000 blood samples taken from patients with malaria-like symptoms in areas of the world where malaria is endemic. In these studies, the sensitivity of the rapid test was 95 percent, and its specificity was 94 percent.
- FDA Press Release. FDA Clears for Marketing First Quick Test for Malaria. June 26, 2007.
- FDA Center for Device and Radiological Health: Consumer Information. Binax Now® Malaria Test - K061542. August 6, 2007.
|Ongoing Safety Analysis for Avandia|
UPDATE: The FDA's Endocrinologic and Metabolic Drugs and the Drug Safety and Risk Management Advisory Committees met on July 30, 2007 to discuss the cardiovascular ischemic/thrombosis risks of thiazolidinedione drugs, with focus on rosiglitazone, as presented by FDA and GlaxoSmithKline. For more information about the meeting, see "Additional Information" link below.
FDA is continuing to review safety data on the drug rosiglitazone maleate. Some of these data suggest that rosiglitazone may increase a patient's risk of heart attack and heart-related deaths compared with other drugs that also treat type 2 diabetes. Rosiglitazone is sold as Avandia, Avandamet and Avandaryl.
A pooled analysis of 42 clinical studies provided by the manufacturer suggested that patients receiving short-term treatment with rosiglitazone may have a 30-40 percent greater risk of heart attack and other cardiovascular events compared with placebo or other anti-diabetic therapy. However, other published and unpublished data from long-term clinical trials provide contradictory evidence about the risk.
It is uncertain at this point whether taking rosiglitazone does increase the risk of these adverse events and if so, by how much. It is also not clear whether pioglitazone, the other approved product in the same drug class, may pose the same risk. Also, switching diabetic patients from one drug to another carries its own inherent risk. Healthcare professionals should consider these factors when deciding about treatment for their diabetic patients. FDA's review of all the available data is continuing.
- FDA MedWatch Safety Alert. Avandia (rosiglitazone). May 21, 2007.
- FDA/Center for Drug Evaluation and Research. Joint Meeting of the Endocrinologic and Metabolic Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee, July 30, 2007. Draft Agenda.
- FDA/Center for Drug Evaluation and Research. Joint Meeting of the Endocrinologic and Metabolic Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee, July 30, 2007. Briefing Information.
|Continuing Recall of MoisturePlus Multipurpose Contact Lens Solution|
In May 2007, Advanced Medical Optics voluntarily recalled its MoisturePlus Multipurpose Solution for contact lenses because using this product may be associated with an increased risk of Acanthamoeba keratitis. This is a rare but serious eye infection that may cause vision loss and require corneal transplant. An investigation by CDC determined that the incidence of Acanthamoeba keratitis was at least seven times greater in users of MoisturePlus than in those using other contact lens solutions.
Cases of Acanthamoeba keratitis associated with the recalled product have continued to be reported to CDC even after the recall was announced in May. This indicates that many consumers may not be aware of AMO’s recall and may still be using the recalled solution.
Clinicians should tell patients to stop using MoisturePlus Multipurpose solution immediately, and to replace their lenses and storage container. They should instruct patients to consult an eye care professional if they have symptoms of an ocular infection, such as redness, pain, excessive tearing, increased light sensitivity, blurry vision or a sensation of something in the eye. This is important because early diagnosis of Acanthamoeba keratitis increases the chance of successful treatment.
FDA is recommending that clinicians consider an Acanthamoeba infection when a patient presents with an infectious keratitis. When appropriate, the patient should be referred to an eye care professional to obtain a corneal scraping for laboratory analysis.
Here are a few recommendations on how to prevent eye infections:
• Remove the lenses before any activity involving contact with water, including showering, using a hot tub or swimming.
• Wash the hands with soap and water and dry them before handling the lenses.
• Use fresh cleaning or disinfecting solution each time the lenses are cleaned and stored. Never re-use or top off old solution.
• And irrigate the storage case with sterile contact lens solution, never tap water, and leave the case open to dry after each use. Replace the case at least once every three months.
- FDA MedWatch Safety Alert. Advanced Medical Optics Complete MoisturePlus Contact Lens Solution. May 29, 2007.
- CDC. Check Your Medicine Cabinet: Consumer Knowledge of Contact Lens Solution Recall. July 31, 2007.
- FDA Center for Devices and Radiological Health. Contact Lenses. July 2007.
|New Warnings on Exjade|
Novartis has notified healthcare professionals that new warnings have been added to the labeling for Exjade (defarasirox). Exjade is used to treat transfusional hemosiderosis, the chronic iron overload that can result from blood transfusions.
Cases of acute renal failure, some of them fatal, have been reported in patients taking this drug. Most occurred in patients with multiple co-morbidities who were in advanced stages of their hematological disorders.
Before beginning therapy with Exjade, all patients should have their serum creatinine assessed in duplicate to establish a baseline level, and then creatinine should be monitored monthly during treatment. Patients who may be at increased risk of complications should be monitored weekly during the first month of Exjade therapy or when the treatment is modified, and then monthly thereafter.
These high-risk patients include the elderly, people with pre-existing renal disease or other co-morbid conditions, and those receiving drugs that can depress renal function.
There have also been reports of cytopenias in patients on Exjade, some of them fatal. The relationship between the drug and these effects is uncertain, since most of the patients had pre-existing hematological disorders that themselves are associated with bone marrow failure. Blood counts should be monitored regularly and treatment interrupted in patients who develop unexplained cytopenia.
|Recall of Abbott Troponin- I Immunoassay|
Abbott Laboratories is conducting a voluntary recall of all lots of the company's ARCHITECT STAT Troponin-I test because of a small number of complaints of inconsistent or invalid results at very low levels of troponin. Some of the invalid results were falsely elevated and some were falsely decreased.
Patient treatment could be affected in either case. A falsely elevated result could lead to needless treatment of a non-existent heart attack, and a falsely decreased result could indicate that the patient had not experienced a heart attack when in fact an MI had taken place.
Laboratories can continue to use this product, but should follow the updated instructions that Abbott has distributed. The company is advising laboratories to be cautious when reporting results at or near the lower limit of detection. They should also advise physicians ordering the tests about the possibility of inaccurate results at those levels, and to re-test in certain circumstances. For more information, laboratories can call Abbott Customer Support at 1-877-422-2688.
|New Warnings for MRI Contrast Agents Containing Gadolinium|
The labeling for imaging contrast agents that contain gadolinium will soon have strong new warnings. These contrast agents are often used to improve the visibility of internal structures when patients undergo MRI procedures. Five of them have been approved in the US: Magnevist, MultiHance, Omniscan, OptiMARK, and ProHance.
The new boxed warning describes risk factors and screening procedures for a serious condition related to gadolinium exposure called nephrogenic systemic fibrosis (NSF). NSF is characterized by fibrosis of the skin, muscle and internal organs. It is debilitating and potentially fatal.
The warning will state that certain patients have a higher risk of developing NSF if they are given a gadolinium-based agent. They include those with severe renal failure, whether acute or chronic, and those with acute renal failure of any severity who have hepato-renal syndrome or are in the perioperative period around liver transplantation. Clinicians should avoid using gadolinium based contrast agents with high-risk patients unless the diagnostic information is essential and cannot be obtained any other way.
The new labeling will contain several other recommendations, including:
• Before using these agents, all patients should be evaluated for renal failure either by obtaining a medical history or conducting laboratory tests.
• When administering these products, do not exceed the dose recommended in the product labeling. And do not re-administer these agents until enough time has elapsed to ensure that the prior dose has been eliminated from the body.
• After administering a gadolinium-based contrast agent, consider prompt dialysis for patients already receiving hemodialysis.
It is unknown whether dialysis prevents NSF, but data indicate that it does speed up the elimination of the agent from the body.
- FDA MedWatch Safety Alert. Gadolinium-Based Contrast Agents for Magnetic Resonance Imaging (MRI): Magnevist, MultiHance, Omniscan, OptiMARK, ProHance. May 23, 2007.
|Dangerous Drug Interaction with Zanaflex|
Acorda Therapeutics recently alerted healthcare professionals about new contraindications for Zanaflex. Zanaflex (tizanidine) is used to treat spasticity.
New labeling says that this drug should not be used concomitantly with either of two CYP1A2 inhibitors: fluvoxamine, which is used to treat depression and anxiety disorders, or the antibiotic ciprofloxacin. Taking either of these drugs together with tizanidine can cause dangerously elevated serum levels of tizanidine, which can lead to side effects such as severe hypotension and sedation.
The company says that other CYP1A2 inhibitors may also lead to substantial increases in tizanidine blood concentrations, although there have been no clinical studies to substantiate this. Therefore, using tizanidine with other CYP1A2 inhibitors should ordinarily be avoided. These drugs include zileuton, other fluoroquinolones, antiarrythmics, H-2 blockers, oral contraceptives, acyclovir and ticlopidine.
- FDA MedWatch Safety Alert. Zanaflex (tizanidine hydrochloride) Tablets and Capsules. April 11, 2007.
|Preventing Malfunctions in Defibrillator Cables and Connectors|
A recent FDA article described several reports of external defibrillators that did not work because of problems with the defibrillator cables and their connectors. Many of these malfunctions occurred with so-called "hands-free" defibrillators, where electrode pads with an adhesive back are attached to the patient and then connected to the defibrillator by a reusable interface cable and connectors. With this configuration, the user does not need to hold wired contact paddles on the patient while the shock is being delivered.
In one report, the hands-free pad would not attach to the interface cable. The nurse discovered that the cable end was broken and so it would not align with the connector of the electrode pad. The break in the cable may have been caused by repeatedly twisting it during daily testing of the defibrillator.
The article lists several ways to minimize these kinds of events during testing and patient defibrillation, including:
• Test the defibrillator at least once a day or according to the facility's or manufacturer's protocol. Be sure to test the unit on battery power only, and ensure that all accessories are present and operate properly. Report any failures, including mechanical faults such as bent or broken connector pins or cables, and electrical malfunctions such as open circuits or failure to deliver the selected energy level.
• When testing the interface cable with an external test load, keep the cables plugged into the test load when the device is not being used. This can reduce wear and tear from frequent attaching and detaching of the connectors and cables.
• Position cables and connectors within easy reach of users. Over-reaching and stretching during a code event may lead to bending or breaking the pins, incomplete mating of the pins, or no connection.
• And train all users to confirm that a positive connection has been made by either checking the display screen or listening for an audible clicking sound. Tell them to look for messages indicating that the connection has or has not been made.
|Helping Patients Keep Track of their Medicines|
FDA has developed a tool, called "My Medicine Record", to help patients keep track of the medicines they use and to make it easier to share this information with their health care providers. The record can be printed out and filled in by hand, or it can be downloaded, filled in and stored on a computer.
If patients keep the record updated and take it with them every time they go to a doctor's office or pharmacy, the pharmacist or physician can quickly review the list of medicines and dietary supplements and troubleshoot any potential problems or interactions. The record can also be sent to the pharmacy or doctor's office electronically.
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