Pharmacology Update

The Latest Information on New Drugs and New Indications

By William T. Elliott, MD, FACP

The cox-2 era has begun now that the fda has approved searle’s celecoxib (Celebrex). Merck is following close on Searle’s heels with their own product refocoxib (Vioxx), for which they are seeking priority review—meaning the drug could be available later this year. The two companies are attempting to position their products so they fill unique niches. Celecoxib is approved for the treatment of rheumatoid arthritis and osteoarthritis but did not receive an indication for pain except for post-dental surgical pain. Merck, on the other hand, has spent extra time with three pain models that will likely result in a pain indication for refocoxib. Merck also has another COX-2 inhibitor beginning Phase III studies later this year.

Emergency physicians may soon be injecting cement into wrist fractures. The FDA has approved Norian SRS Cement manufactured by Norian Corporation. A study of 161 patients with simple wrist fractures revealed that injection of the cement into the fracture site shortened the required time for casting from 6-8 weeks to two weeks. The cement is eventually replaced by bone. There is concern that patients treated with the cement lost more bone length than those treated in the conventional way and the FDA is asking Norian to study this as well as the risk of refracture in post-approval studies.

The FDA has also given SmithKline Beecham approval to market the first Lyme disease vaccine (LYMErix). The vaccine, which contains a genetically engineered surface protein from Borrelia burgdorferi, is given in three injections over one year at 0, 1, and 12 months. It is only 78% effective in preventing the disease, so high-risk patients should continue to use standard Lyme preventive measures such as protective clothing and tick repellants. The vaccine is approved for people 15-70 years old who live or work in grassy or wooded areas where Lyme disease is a known risk.

Gabapentin (Neurontin; Parke-Davis) has been shown to be effective in treating two of the most refractory painful neuropathies—diabetic neuropathy and postherapeutic neuralgia. In back-to-back papers in JAMA (JAMA 1998;280:1831-1836;1837-1842), gabapentin was found to be significantly more effective than placebo in relieving symptoms of these peripheral neuropathies. In both studies, not only was pain relieved, but other quality-of-life measures were improved including sleep interference and mood.

Does eradicating Helicobacter pylori help patients with nonulcer dyspepsia? Two recent European studies seem to disagree (N Engl J Med 1998;339:1869-1881; 1928-1930). The first study from Glasgow compared omeprazole alone with omeprazole and antibiotics in 318 patients with nonulcer dyspepsia and a positive breath test for H. pylori. The combination therapy eradicated H. pylori in 88% of patients compared to 7% for omeprazole alone. At one year, 21% of the combination therapy patients had significant relief of their symptoms compared to 11% in the monotherapy group. In the second study, a Swiss group structured their study of 328 patients in a similar way but found no difference in symptomatology in the two groups at one year.

Amiodarone (Cordarone; Wyeth-Ayerst) may be effective in converting atrial fibrillation to normal sinus rhythm and preventing atrial fibrillation in patients with congestive heart failure. In a study from UCSF (Circulation 1998;98:2574-2579), 667 CHF patients were randomized to amiodarone or placebo. About 50 people in each group were in atrial fibrillation at the start of the study. Amiodarone prevented atrial fibrillation in those with normal sinus rhythm compared to placebo (11 new atrial fib in the treatment group vs 22 new atrial fib in the placebo group). The drug also converted about 30% of atrial fibrillation patients to NSR compared to 8% converting in the placebo group. Mortality was significantly lower in those who converted to NSR.

Other news from the FDA:

Cefpodoxime (Vantin; Pharmacia & Upjohn) has been approved for five-day treatment of otitis media in children and sinusitis in adults, adolescents, and children.

Ribavirin/interferon alfa-2B (Rebetron; Schering) has been approved for treatment of hepatitis C in treatment-naïve patients. It had previously only been approved for patients who had failed interferon therapy.

• Micronized "natural" progesterone (Prometrium-Solvay) has been approved for use with estrogen in the role of hormone replacement therapy in women without a history of hysterectomy. The PEPI trial suggested that micronized progesterone may be safer than other progestins in this role.

Raloxifene (Evista; Eli Lilly) has been approved to change its package insert to include breast cancer prevention although the labeling also states that the effectiveness of raloxifene in reducing the risk of breast cancer has not been established.

Merck is alerting physicians of the rare occurrence of Churg-Strauss syndrome in association with the use of the asthma drug montelukast (Singulair). This, and other eosinophilic conditions, has been noted especially when steroids are withdrawn.