Once Again, CDC Predicts Flu Vaccine Delays
By William T. Elliott, MD, FACP
The Centers for Disease Control are warning that this fall’s flu vaccine may be delayed again. The delay is not expected to be as severe as last year’s vaccine shortage and stems from different problems. Last year, compliance and manufacturing problems resulted in a severe shortage of vaccine. This year, the delay will be caused by less manufacturing capacity as the number of manufacturers has dropped from 4 to 3. Still, the CDC predicts that 64% of the vaccine will be available by the end of October, more than twice the amount available in October last year, with the remaining doses available by November or December.
Antibiotics
Aventis’ telithromycin (Ketek), the first of a new class of antibiotics, has received an "approvable" letter from the FDA. The drug, which can be taken orally once a day, will be indicated for upper and lower respiratory tract infections including community acquired pneumonia. Telithromycin is the first of a class of antibiotics known as ketolides. An approvable status outlines conditions that must be met before the FDA will approve a drug.
Estrogen Replacement Therapy (ERT)
Healthy postmenopausal women have better blood pressure regulation while on ERT, suggesting that estrogen plays a role in the ability of the nervous system to control blood pressure. In a recent study appearing in Circulation, none of the women had hypertension at baseline. In a separate study in the same journal, researchers found that transdermal estrogen was better at regulating blood pressure than oral estrogen. It is postulated that since transdermal estrogen bypasses enterohepatic circulation, more of the hormone is available systemically (Circulation. 2001;103:2903-2908; Circulation. 2001;103:2909-2914).
ERT may reduce the risk of cataracts according to the Framingham Eye Study. Women who took ERT the longest were the least at risk for developing cataracts. Odds ratios were: never users = 1.0; 1-2 years = 0.8; 3-9 years = 0.7; 10 or more years = 0.4 (Arch Intern Med. 2001;161:1448-1454).
Hypothyroid women on thyroxine may need to have their dose increased when they are started on ERT. Estrogen leads to an increase in thyroxine-binding globulin and a decrease in serum-free thyroxine. They suggest checking thyroid functions 12 weeks after initiating ERT and adjusting thyroxine doses appropriately (N Engl J Med. 2001;344:1743-1785).
Insulin
The search for a noninjectable insulin product looks promising. Pfizer and Aventis Pharmaceuticals are partnering on the development of an inhaled insulin product. Phase III data presented at the American Diabetes Association’s meeting suggests that a single bedtime injection of ultralente with daytime inhaled insulin is at least as effective as subcutaneous insulin injections. The drug was evaluated in both type 1 and 2 diabetics. Inhaled insulin-induced insulin antibodies developed higher levels of insulin antibodies, but the clinical significance of this finding is unclear.
Progress on an oral insulin product was also presented at the ADA meeting. The insulin molecule is suscepti- ble to degradation in the gut, but by attaching various polymeric oligomers, the molecule can be absorbed. Oral insulin is currently in phase III trials.
Statin Therapy
High C-reactive protein (CRP) levels are a predictor of future coronary events and stroke. Studies have suggested that statins reduce CRP levels. A new study shows that this effect translates into lower rates of heart disease, even in patients with high CRP levels and low lipids. More than 5700 patients were randomized to treatment with lovastatin or placebo. In patients with low lipids, lovastatin reduced CRP levels by 14.8%, and those patients also had a lower incidence of coronary events. An accompanying editorial suggests that measuring CRP levels along with lipid levels may become routine in healthy adults (N Engl J Med. 2001;344:1959-1965; N Engl J Med. 2001;344:2016-2018).
Lyme Disease
A single 200-mg dose of doxycycline given within 72 hours of a tick bite is highly effective at preventing Lyme disease. Researchers from New York randomized 482 patients who had been bitten by Ixodes scapularis to doxycycline or placebo. Of those tested, 3.2% of placebo patients developed erythema migraines compared to only 0.4% of doxycycline-treated patients. One-third of doxycycline patients noted side effects, primarily nausea and vomiting. The study is to be published in the July 12 edition of New England Journal of Medicine, but the findings were released early on the journal’s web site because of the importance of the findings.
FDA News
The FDA status of levothyroxine (Synthroid) is in limbo despite a 40-year safety record. Prior to 1962, drugs were not required to file a New Drug Application (NDA). Synthroid was released in 1958, and therefore never submitted a NDA. The FDA recently notified Abbott Labs that the company needed to file documentation showing the safety and efficacy of Synthroid. Abbott requested a waiver, but the FDA denied their request. In the meantime, 2 advocacy groups, the National Organization of Women and the Grey Panthers are demanding that the drug be withdrawn from the market because it hasn’t demonstrated safety and efficacy. The American Association of Clinical Endocrinologists has countered in rather strongly worded fashion suggesting that removing the drug would be "extremely misguided and unwarranted."
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