Pharmacology Update
Pharmacology Update
The Latest Information on New Drugs and New Indications
By William T. Elliott, MD, FACP
Are we treating venous thromboembolism long enough? the first episode of venous thrombosis, in the absence of pulmonary embolism, is generally treated with anticoagulant therapy for three months. Canadian and U.S. researchers recently looked at 162 patients who had received their three months of anticoagulation therapy (Kearon C, et al. N Engl J Med 1999;340:901-907), then randomized them to either placebo or continued anticoagulation. The study was terminated early when more than 27% of the placebo group experienced recurrent venous thromboembolis (17 out of 83). Of the treatment group, averaging 10 months of anticoagulation with warfarin, three had nonfatal major bleeding (2 GI bleeds and 1 GU bleed), and only one had a recurrent thrombosis. Kearon and colleagues conclude that six months of anticoagulation or even longer may be appropriate for patients with venous thromboembolism.
As of April, the FDA is requiring dietary supplements to carry more complete labeling information about their ingredients. Supplements must now carry a panel that displays the quantity of specific nutrients and the common name of any herbal ingredients. The FDA’s ruling is one of the provisions of the new dietary supplements law that requires supplements to be treated like other food and drug products.
Warner Lambert’s troglitazone (Rezulin) has been the subject of intense scrutiny after more than 40 cases of liver failure have been associated with use of the drug. The UK and several other European countries have already withdrawn the diabetes drug from the market, and it was expected that the FDA might take some sort of action of its own. However, in late March, the Endocrinologic and Metabolic Drugs Advisory Committee of the FDA did not recommend any major labeling changes, although they did state that the drug should not be used as monotherapy for type 2 diabetes. Parke-Davis, the division of Warner Lambert that markets troglitazone, issued a warning last year advising physicians to monitor patients started on the drug with liver function tests every month for the first eight months of therapy, and every two months for the rest of the first year. Two new drugs in the same class as troglitazone are expected to hit the market in the next year—SmithKline Beecham’s rosiglitazone (Avandia) and Eli Lilly’s pioglitazone (Actos).
There is increasing evidence that postmenopausal estrogen replacement may reduce the risk of developing Alzheimer’s disease (AD). In a recent case control study (Waring SC, et al. Neurology 1999;52:967-970), researchers from the Mayo clinic found that women with AD were far less likely than nondemented women to have undergone estrogen replacement therapy for any length of time. The researchers admit that even with careful case control matching for education and age at menopause, there may be other confounding factors that affect the results of the study and the authors call for further studies to elucidate the significance of their findings.
One of the hottest topics in U.S. medicine this year is the potential relationship between Chlamydia pneumoniae infection and coronary artery disease (CAD). More than 20 reports have been published demonstrating the presence of C. pneumoniae in atherosclerotic plaques, but the clinical significance of this association is unclear. A group from the University of Utah has published the initial six-month results from a two-year study of 302 patients with CAD and serologic evidence of C. pneumoniae infection. Patients were randomized to treatment with azithromycin or placebo (Grayston JT, et al. Circulation 1999;99:1538-1547). At six months, markers or inflammation were reduced in the treatment group, but there was no difference in the rate of coronary events. The study will continue along with other studies looking at the same issue, with results expected in two to three years.
Pfizer’s sildenafil (Viagra) may not be effective in women according to a nonrandomized study from Columbia Presbyterian in New York (Kaplan C, et al, Urology 1999;53:481-486). In 33 postmenopausal women with self-described sexual dysfunction who tried the drug for six months, there was no significant improvement in sexual desire or satisfaction with intercourse. Kaplan and colleagues admit that this is a small, uncontrolled trial, but the data show little support for use of the drug in postmenopausal women.
Direct-to-consumer advertising is becoming a big business in this country. Many pharmaceutical companies are now spending more money advertising to patients than they are spending on professional advertising. During the first six months of 1998, the makers of four drugs, Claritin, Pravachol, Zyban, and Zyrtec, spent almost $200 million on direct to consumer advertising, while spending a little more than half that amount on professional advertising. The overall industry budget for direct-to-consumer advertising reached $1.3 billion in 1998 and is expected to increase another 30% this year.
The next COX-2 inhibitor, Merck’s rofecoxib (Vioxx) will soon be reviewed by the FDA’s Arthritis Advisory Committee on April 20. Merck is petitioning for a pain indication as well as an indication for the treatment of osteoarthritis. Searle’s celecoxib (Celebrex), which was approved on December 31, 1998, has the makings of a blockbuster drug, with brisk early sales. Celecoxib, however, only received an indication for treatment of arthritis, a difference that Merck is hoping to exploit in its marketing of Vioxx when it is approved later this year.
Are angiotensin II receptor antagonists as effective as ACE inhibitors in the treatment of heart failure? Researchers are looking at Bristol-Meyers Squibb’s irbesartin (Avapro) in the Irbesartin Heart Failure Group, which will attempt to answer this question. Initial results reported recently (Havranek EP, et al. J Am Coll Cardiol 1999;33:1174-1181) showed significant improvement in hemodynamics in NYHA class II-IV patients after 12 weeks of therapy. Once-daily doses of 75-150 mg of irbesartin significantly reduced pulmonary capillary wedge pressure and prevented worsening of heart failure. Head- to-head studies with ACE inhibitors need to be performed to fully compare the two drug classes in heart failure patients.
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