Bird Flu Vaccine Looks Promising
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In This Issue: Baxter Bioscience has developed a whole-virus, two dose vaccine against avian flu; warning label now on antipsychotics regarding an increased risk of mortality in elderly patients treated for dementia-related psychosis; vitamin D for men with heart disease on horizon? A new oral anticoagulant may soon be available for prevention of thrombotic complications of hip or knee surgery; FDA Actions
An effective two dose vaccine has been developed against the avian flu (H5N1 virus) according to a recent study in the New England Journal of Medicine. Researchers from Baxter Bioscience have developed a whole-virus vaccine that was tested on 275 volunteers between the ages of 18 and 45 years. Four different strengths of the vaccine were tested with and without adjuvant. The most effective regimen was a dose of either 7.5 µg or 15 µg of hemagglutinin given without adjuvant 21 days apart. The vaccine was effective at inducing neutralizing antibody response against three different viral strains. Mild pain at the injection site and headache were the most common adverse effects. The authors conclude that a two dose vaccine regimen of either 7.5 µg or 15 µg induced neutralizing antibodies against diverse H5N1 viral strains in a high percentage of subjects (NEJM. 2008;358:2573-2584).
Boxed warning now required for antiphychotics for elderly with dementia
The FDA is requiring a boxed warning for conventional antipsychotics regarding an increased risk of mortality in elderly patients treated for dementia-elated psychosis. This expands the warning on the newer atypical antipsychotics which was issued in April 2005 to include the older, more conventional antipsychotics. The new warning includes medication such as haloperidol (Haldol), thioridazine (Mellaril), and chlorpromazine (Thorazine). The warning specifically states that elderly patients with dementia-related psychosis treated with conventional or atypical antipsychotic drugs are at increased risk of death. Antipsychotic drugs are not approved for the treatment of dementia-related psychosis, and physicians who prescribe antipsychotics for elderly patients with dementia-related psychosis should discuss this risk of increased mortality with their patients, patient's families, and caregivers. It was previously thought only the newer, atypical antipsychotics were associated with increased mortality; however, multiple studies have now shown that the older antipsychotics also increase the risk. The warning can be found on the FDA web site at www.FDA.gov.
Vitamin D for men with heart disease?
Men may be asking about prevention of heart disease with vitamin D based on this reports of recent studies. In a follow-up from the Health Professionals Follow-up Study (HPFS) from the Harvard School of Public Health, plasma 25-hydroxyvitamin D levels were measured on over 18,000 male healthcare professionals age 40 to 75 years, who were free of diagnosed cardiovascular disease at blood collection. In 10 years of follow-up, 450 men had nonfatal myocardial infarction or fatal coronary heart disease. After adjustment for matched variables, and men deficient in 25-hydroxyvitamin D (£ 15ng/ml) were at increased risk of MI compared to those considered to be sufficient (≥ 30ng/ml) (RR 2.42; 95% CI, 1.53-3.84; P <.001 for trend). After adjustment for family history and multiple risk factors, the relationship remains significant. Even those with levels 22.6 to 29.9 ng/ml were at higher risk than those with levels over 30 ng/ml. The authors conclude that "low levels of 25-hydroxyvitamin D are associated with a higher risk of myocardial infarction in a graded manner even after controlling for factors noted to be associated with coronary disease." The mechanism for this relationship is unclear but may be related to vitamin D, its effect on vascular smooth muscle proliferation, inflammation, vascular calcification, and blood pressure. Whether vitamin D supplementation reverses these findings remains be seen, but it is clear that men with low vitamin D levels will require more than the current recommended daily allowance of 200-600 IU/d, perhaps even as much as 3000 IU/day (Arch Int Med. 2008;168:1174-1180). Another study with similar conclusions was recently published (Arch Intern Med. 2008;168:1340-1349).
New oral anticoagulant tested for patients with hip or knee surgery
A new oral anticoagulant may soon be available for prevention of thrombotic complications of hip or knee surgery. Rivaroxaban is an oral direct inhibitor of factor Xa that is in phase 3 trials by Bayer and Ortho-McNeil Pharmaceutical. The drug has the advantage of being highly bioavailable when given orally and has a standard 10-mg dose given once a day. In 3 recent trials, rivaroxaban was compared to subcutaneous enoxaparin after total hip arthroplasty and total knee arthroplasty. Over 7000 patients were randomized to receive rivaroxaban 10 mg daily beginning after surgery or subcutaneous enoxaparin 40-mg once daily beginning the day before or the day of surgery. A third study compared long-term use of rivaroxaban with short-term use of enoxaparin. The primary outcomes included deep venous thrombosis, pulmonary embolism, and all cause mortality. In all 3 studies thromboprophylaxis with rivaroxaban was significantly more effective than enoxaparin, while toxicity, specifically major bleeding, was the same in both groups. The authors conclude that a once-daily 10-mg oral dose of rivaroxaban is significantly more effective than a 40 mg subcutaneous dose of enoxaparin in preventing thrombotic complications in patients undergoing total hip or total knee arthroplasty (NEJM. 2008;358:2765-2775, 2776-2786. Lancet 2008 published early online 25 June 2008). While rivaroxaban is not yet approved in this country, the prospect of an orally active direct Xa inhibitor that could take the place of parenteral heparin compounds and perhaps even warfarin is exciting to clinicians.
FDA Actions
The FDA has approved a new pentavalent vaccine for children age 6 weeks through 4 years. The new vaccine combines diphtheria, tetanus, pertussis, poliomyelitis, and Haemophilus influenza type b. It is given as a 4 dose series at 2, 4, 6 and 15-18 months of age. The vaccine is marketed by Sanofi Pasteur as "Pentacel." GlaxoSmithKline has also received approval for a combination vaccine with diphtheria, tetanus, acellular pertussis, and polio for children 4 to 6 years old who require their fifth DTaP and fourth polio shot. The combination vaccine may prevent additional injections for these children. This four vaccine combination will be marketed as "Kinrix."
The FDA has issued warning letters to 23 US companies and two foreign individuals regarding the marketing of fake cancer cures on the Internet. The products which include tablets, tonics, black salves, and creams are fraudulently promoted, claiming to prevent and cure cancer. The products contained in treating such is bloodroot, shark cartilage, coral calcium, cesium, Cat's Claw, herbal tea and mushrooms. A complete list of companies and individuals concluded and the warning can be found at www.fda.gov.
This supplement was written by William T. Elliott, MD, FACP, Chair, Formulary Committee, Kaiser Permanente, California Division; Assistant Clinical Professor of Medicine, University of California-San Francisco. In order to reveal any potential bias in this publication, we disclose that Dr. Elliott reports no consultant, stockholder, speaker's bureau, research, or other financial relationships with companies having ties to this field of study. Questions and comments, call: (404) 262-5431. E-mail: [email protected].
Baxter Bioscience has developed a whole-virus, two dose vaccine against avian flu; warning label now on antipsychotics regarding an increased risk of mortality in elderly patients treated for dementia-related psychosis; vitamin D for men with heart disease on horizon? A new oral anticoagulant may soon be available for prevention of thrombotic complications of hip or knee surgery; FDA ActionsYou have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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